evaluation of the curing times of strippable coatings and

EPA/600/R-14/238 | September 2014 | www.epa.gov/nhsrc

Evaluation of the Curing Times of Strippable Coatings and Gels as used for Radiological Decontamination

EVALUATION REPORT

Office of Research and DevelopmentNational Homeland Security Research Center

ii

Evaluation of the Curing Times of Strippable Coatings and Gels

as used for Radiological Decontamination

Evaluation Report

National Homeland Security Research Center Office of Research and Development

U.S. Environmental Protection Agency Research Triangle Park, NC 27711

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Disclaimer The United States Environmental Protection Agency through its Office of Research and Development’s National Homeland Security Research Center, funded and managed the research described here under EPA Contract Number EP-C-09-027, Work Assignment 4-11 with ARCADIS U.S., Inc. This report has been peer and administratively reviewed and has been approved for publication as an Environmental Protection Agency report. It does not necessarily reflect views of the Environmental Protection Agency. No official endorsement should be inferred. The Environmental Protection Agency does not endorse the purchase or sale of any commercial products or services. Questions concerning this document or its application should be addressed to: Lukas Oudejans, Ph.D. Decontamination and Consequence Management Division National Homeland Security Research Center Office of Research and Development U.S. Environmental Protection Agency (MD-E343-06) 109 T.W. Alexander Dr. Research Triangle Park, NC 27711 Phone: 919-541-2973 Fax: 919-541-0496 E-mail: [email protected]

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Acknowledgments Contributions of the following individuals and organizations to the development of this document are gratefully acknowledged. United States Environmental Protection Agency (EPA): John Griggs, Office of Air and Radiation (OAR)/Office of Radiation and Indoor Air (ORIA) Terry Stilman, Region 4 James Mitchell, Region 5 Ramona Sherman (QA review), Office of Research and Development (ORD)/ National Homeland Security Research Center (NHSRC) ARCADIS U.S., Inc. This report builds on published EPA radiological decontamination reports and technical briefs in which decontamination factors for a select number of decontamination technologies were measured. The contributions to that work by John Drake (ORD/NHSRC, retired) are greatly acknowledged.

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Table of Contents

Disclaimer ............................................................................................................... iii Acknowledgments .................................................................................................. iv

Table of Contents ..................................................................................................... v

List of Figures ........................................................................................................ vii List of Tables ........................................................................................................ viii Acronyms and Abbreviations ............................................................................... ix

Executive Summary ................................................................................................. x

1.0 Introduction ......................................................................................................... 1

1.1 . Purpose ............................................................................................................................................. 1 1.2 . Project Objectives ............................................................................................................................ 2

2.0 Experimental Approach ..................................................................................... 3

2.1 . Experimental Test Chamber ............................................................................................................ 4 2.2 . Environmental Controls ................................................................................................................... 5

2.2.1 Temperature Control ......................................................................................................... 6 2.2.2 RH Control ........................................................................................................................ 6 2.2.3 Pressure Control ................................................................................................................ 7 2.2.4 Aeration Rate Control ....................................................................................................... 7 2.2.5 Chemical Fume Hood for Decontaminant Preparation ..................................................... 8

2.3 . Test Materials .................................................................................................................................. 8 2.3.1 Coupon preparations ......................................................................................................... 9

2.4 . Selected Decontamination Technologies ....................................................................................... 10 2.4.1 InstaCote CC Wet/CC Strip ............................................................................................ 10 2.4.2 CBI DeconGel® 1108 ...................................................................................................... 12 2.4.3 Bartlett StripCoat TLC Free™ ........................................................................................ 13

2.5 . Test Matrix ..................................................................................................................................... 14 2.6 . Preparation of Coupons for Testing ............................................................................................... 15

2.6.1 Wetted coupon preparation ............................................................................................. 16 2.7 . Preparation and Application of the Decontamination Agents........................................................ 18

2.7.1 Decontamination Coating Amounts ................................................................................ 18 2.8 . Procedure to Determine Curing Status .......................................................................................... 20 2.9 . Curing Status Definitions ............................................................................................................... 20

3.0 Test Results and Discussion .............................................................................22

3.1 . CC Wet/CC Strip ........................................................................................................................... 22 3.2 . DeconGel® 1108 ............................................................................................................................ 26 3.3 . Stripcoat TLC Free™ .................................................................................................................... 30

4.0 Quality Assurance and Quality Control .........................................................32

4.1 . Data Quality Objectives ................................................................................................................. 32 4.2 . Data Quality Indicators .................................................................................................................. 32 4.3 . Equipment Calibrations ................................................................................................................. 33 4.4 . Quantitative Acceptance Criteria ................................................................................................... 33 4.5 . Amendments and deviations from the original QAPP ................................................................... 36

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4.5.1 Formal Amendments ....................................................................................................... 36 4.5.2 QAPP Deviations ............................................................................................................ 37

5.0 Summary ............................................................................................................38

6.0 References ..........................................................................................................40

Appendix A: Loading volumes versus environmental conditions .....................41

Appendix B: Critical and non-critical measurements ........................................44

Appendix C: RH profiles during curing of decontamination coatings .............51

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List of Figures

Figure 2-1. Decontamination chamber. ......................................................................................... 4

Figure 2-2. Decontamination chamber schematics. ....................................................................... 5

Figure 2-3. Coupons assembled for testing.................................................................................. 16

Figure 2-4. Top- and side-view of concrete coupon soaking up the water after application of the simulated rainfall. ......................................................................................................................... 17

Figure 2-5. Scheme of the successive attempts to peel off decontamination coating from coupon surface. .......................................................................................................................................... 20

Figure 3-1. Appearance of the overly dried-out CC Wet/CC Strip coating (5 °C/20 %RH/1 ACH/dry surface, 4 h post-application of CC Strip coat). ............................................................ 22

Figure 3-2. Several-piece-removal of CC Wet/CC Strip coating (20 °C/80 %RH/1 ACH/dry surface; 4 h post-application of CC Strip coat). ............................................................................ 23

Figure 3-3. One-piece-removal of CC Wet/CC Strip coating from stainless steel (40 °C/20 %RH/1 ACH/dry surface; 4 h post-application of CC Strip coat). ............................................... 23

Figure 3-4. One-piece-removal of CC Wet/CC Strip coating from concrete (40 °C/20 %RH/1 ACH/dry surface; 4 h post-application of CC Strip coat). ............................................................ 24

Figure 3-5. One-piece-removal of DeconGel® 1108 coating from stainless steel (5 °C/80 %RH/1 ACH/dry surface, 18 h post-application of 2nd coat). ................................................................... 26

Figure 3-6. One-piece-removal of DeconGel® 1108 coating from concrete (5 °C/80 %RH/1 ACH/dry surface, 18 h post-application of 2nd coat). ................................................................... 26

Figure 3-7. Partial removal of semi-cured DeconGel® 1108 coating (20 °C/80 %RH/1 ACH/dry surface, 32 h post-application of 2nd coat). ................................................................................... 27

Figure 3-8. Almost-cured DeconGel® 1108 coating (5 °C/80 %RH/1 ACH/dry surface, 4 h post-application of 2nd coat). ................................................................................................................. 28

Figure 3-9. One-piece-removal of Stripcoat TLC Free™ coating from concrete (20 °C/20 %RH/1 ACH/dry surface, 4 h post-application of 2nd coat). ........................................................ 30

Figure 3-10. One-piece-removal of Stripcoat TLC Free™ coating from stainless steel (20 °C/20 %RH/1 ACH/dry surface, 4 h post-application of 2nd coat). ........................................................ 30

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List of Tables Table ES-1. Summary of shortest curing times and major observations for tested strippable coatings at one air change per hour. ............................................................................................... xi

Table 2-1. Description of building materials for curing time testing. ........................................... 9

Table 2-2. Decontamination agents and technologies used for curing times testing. .................. 10

Table 2-3. Test matrix for each decontamination technology. .................................................... 15

Table 2-4. Simulated rainfall parameters. .................................................................................... 18

Table 2-5. Average loading volumes per surface area for decontamination coatings tested. ...... 19

Table 3-1. Assessment of CC Wet/CC Strip curing times with opacity rating of coating under various environmental conditions with normal ventilation. ......................................................... 25

Table 3-2. Assessment of the DeconGel® 1108 curing times under various environmental conditions with normal ventilation. .............................................................................................. 29

Table 3-3. Assessment of the Stripcoat TLC Free™ curing times under various environmental conditions with normal ventilation. .............................................................................................. 31

Table 4-1. DQIs for critical measurements. ................................................................................. 33

Table 4-2. Equipment calibration schedule. ................................................................................ 33

Table 4-3. Acceptance criteria for critical measurements. .......................................................... 34

Table 4-4. Summary of critical measurements and completeness of data. .................................. 35

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Acronyms and Abbreviations

ACH air change(s) per hour DI deionized DQI data quality indicator DTRL Decontamination Technologies Research Laboratory EPA U.S. Environmental Protection Agency ft3 cubic feet or foot h hour(s) L liter(s) min minute(s) mL milliliter(s) mm millimeter(s) MSDS Material Safety Data Sheet NHSRC National Homeland Security Research Center NIST National Institute of Standards and Technology ORD Office of Research and Development OSC On-Scene Coordinator PDAQ portable data acquisition (system) PPE personal protective equipment QA Quality Assurance QAPP Quality Assurance Project Plan QC Quality Control RDD Radiological Dispersal Device RH Relative Humidity SD Standard Deviation sec second(s)

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Executive Summary In 2010, federal, state, and local authorities participated in a five-day Homeland Security

exercise in Philadelphia, PA. This Liberty RadEx exercise was designed to test the country’s

capability to clean up and help communities recover from a radiological dispersal device (RDD)

detonation. As part of this exercise, various decontamination technologies for the removal of

radionuclides from building materials were demonstrated. One of these demonstrations involved

the application of a strippable coating to wall and floor surfaces of the city’s subway system.

This method of decontamination had previously been investigated on the laboratory scale as a

potential method for removal of radionuclides from an urban building surface. One of the

observations made during the Liberty RadEx exercise was that the coating did not cure properly

over an extended period of time (more than 24 hours) while the curing time stated by the

manufacturer was (at that time) 4 to 6 hours, depending on environmental conditions. The failure

to cure was postulated as being due to either the high relative humidity (RH) and/or the stagnant

air in the enclosed area as experienced during the demonstration.

This project evaluated the impact that environmental conditions may have on the ability of

strippable coatings to cure properly on a representative building material in the urban

environment. This first report describes the impact of temperature and RH at a fixed single air

change per hour rate. The three decontamination products evaluated in this study were selected

based on their previously observed ability for successful in situ removal of radionuclides from

building materials (EPA 2011a, EPA 2011b, EPA 2013a, EPA 2013b). The three strippable

decontamination coatings tested, InstaCote CC Wet/CC Strip, CBI Polymers DeconGel® 1108,

and Bartlett Nuclear Inc. StripCoat TLC Free™, were applied to concrete and stainless steel

coupons. The curing process of these coatings was tested under various environmental conditions

ranging from just above the freezing point of the products (5 °C) at low (20 %) and high (80 %)

RH to a summer-like temperature of 40 °C at low and high RH. Up to four attempts were made

to remove a strippable coating from the surfaces, namely 4 hours (h), 18 h, 24 h, and 32 h after

application of the product.

Table ES-1 summarizes the observed curing time for these coatings for all conditions tested.

Curing was defined here as the ability to peel the coating from the stainless steel and concrete

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surfaces as one single piece (“Excellent”) or several smaller pieces (“Good”) without leaving

areas of uncured coating present on a coupon surface. Partial curing was defined when the

coating could be removed only partially due to the presence of wet spots or if the peeling process

resulted in numerous small dried out pieces of coating. No curing was defined when coatings

were wet and did not peel from the surfaces.

Table ES-1. Summary of manufacturer information and observed shortest curing times for tested strippable coatings at one air change per hour. CC Wet/CC Strip DeconGel® 1108 Stripcoat TLC Free ™

Manufacturer recommended curing time

24 h at high RH, low temp, no ventilation

hours for thin coatings to overnight or longer for

thick coatings and high RH

4-10 h, depending on coat thickness and RH

Environmental Condition Observed curing times (h)/observations

5°C/20 %RH/dry surface 4/multiple piecesa 18/one piece 4/one piece

5°C/80 %RH/dry surface 4/several pieces 18/one piece 4/one piece

20°C/20 %RH/dry surface 4/several pieces 4/one piece 4/one piece

20°C/80 %RH/dry surface 4-23/several piecesb > 32h/semi cured at 32 hc 4/one piece

40°C/20 %RH/dry surface 4/one-several pieces 4/one piece 4/one piece

40°C/80 %RH/dry surface 4/one piece 18/one-several piece(s) 4/one piece

20°C/80 %RH/wet surface 4/one-several pieces 18/one piece 4/one piece a Loss of elasticity of coating resulted in multiple small pieces being removed; complete removal was achieved. b One vertical concrete coupon coating wet after 4 h; multiple pieces with low elasticity after 23 h for one concrete

coupon. c Complete curing after 48 h.

The curing was found to be very rapid under mild/warm (20 ºC/40 ºC) temperature and low

humidity (20 % RH) environmental conditions, when all coatings tested were strippable at 4 h

post-application. The surface characteristics (wet or dry) did not cause differences in the curing

process, but high humidity and cold temperatures seemed to be drivers for prolonged curing

times for some strippable coatings (e.g., CC Wet/CC Strip and DeconGel® 1108).

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The observed curing of CC Wet/CC Strip always occurred within 24 h post-application - the time

period recommended by the manufacturer for processing of this coating under worst case

environmental conditions (high humidity, low temperatures, no ventilation). Similarly for

DeconGel® 1108, the observed overnight or longer curing times are in line with the

recommended curing time by the manufacturer. As indicated by the manufacturer, drying times

exceeding 24 h may be required for decontamination scenarios where thicker coatings are

applied in humid environments. StripCoat TLC Free™, which has the shortest manufacturer-

recommended curing times (4-10 h) amongst all strippable coatings tested formed strippable

coatings at 4 h post-applications under all environmental conditions tested.

Results from this study confirm that environmental conditions have an impact on the curing time

of two of the three tested strippable coatings. However, the occasionally observed prolonged

curing time was always less than the manufacturer’s provided information. Curing times do

differ across products.

Loading volumes (hence, the thickness) of a coating material per surface test area were

dependent on RH and to a lesser extent temperature. Lower loading volumes were observed

when coatings were applied under high humidity conditions. Temperature-related changes in

loading volumes varied across decontamination products. The impact of the coating thickness on

the curing time was not explicitly determined in this study. However, the impact of the coating

thickness on the curing time appears to be low as all coatings cured within the vendor-

recommended curing times.

All strippable decontamination coatings tested were easy to apply, with no requirement for a pre-

preparation process. None of the products posed major challenges during the application using

the brush-on technique employed in this study.

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1.0 Introduction In 2010, federal, state, and local authorities participated in a five-day Homeland Security

exercise in Philadelphia, Pennsylvania. This exercise, called Liberty RadEx, was designed to test

the country’s capability to clean up and help communities recover from a radiological dispersal

device (RDD) detonation. As part of this exercise, various decontamination technologies were

demonstrated for the removal of radionuclides from building materials. One of these

demonstrations involved the application of a strippable coating to wall and floor surfaces of the

city’s subway system. This method of decontamination had previously been investigated on the

laboratory scale as a potential method for removal of radionuclides from an urban building

surface. One of the observations made during Liberty RadEx was that the coating did not cure

properly over an extended period of time (more than 24 h) while the curing time stated by the

manufacturer was 4 – 6 h, depending on the environmental conditions. The failure to cure was

postulated to be due to the high relative humidity (RH) and the low ventilation environment

experienced during the demonstration in the enclosed area.

Strippable coatings are examples of surface cleaning technologies that most likely would be

employed to decontaminate surfaces for which minimal destruction is desired. These would

include materials that are part of infrastructure of high economic, cultural, or historical

significance. Strippable coatings would also be useful in creating a protective layer on a

contaminated surface as to avoid further penetration of radionuclides into a porous building

material.

1.1 Purpose

The purpose of this work was to evaluate the impact that environmental conditions may have on

the ability of strippable coatings to cure properly on a representative building material in the

urban environment. Curing of these coatings is critical to obtain high contaminant-removal

efficiency as the coating traps the targeted radionuclides. Only removal of the coating leads to

removal of the radionuclides. Uncured coating left on the surface would result in a lower

removal efficacy of the surface. This work did not assess the impact that these environmental

conditions may have on the decontamination efficacy (removal of radionuclides from a surface)

2

of the technology. Efficacies against various radionuclides were determined previously (EPA

2011a) for these and other decontamination technologies at approximately 20 °C and 20 %RH.

1.2 Project Objectives

The specific project objectives to achieve the overall purpose consisted of:

• a systematical assessment of the curing process as a function of time through measurement of

the ability to peel the strippable coating from a surface under different environmental

conditions, e.g., temperature, RH, and air change conditions; and

• an assessment of whether the orientation of the surface (vertical versus horizontal) affects the

curing time.

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2.0 Experimental Approach The general technical approach was to use a modified glove box to establish controlled

temperature, RH, and air change conditions that mimic a range of environmental conditions that

may be encountered during the remediation of an industrial or municipal setting following a

release or detonation of an RDD. Building coupons (concrete and stainless steel) were allowed to

equilibrate for a specified period of time within the controlled environmental conditions of the

modified glove box prior to application of the decontamination coating under the set of

conditions. The equilibration period of the materials was at least 48 h long. A decontamination

coating was then applied according to the manufacturer’s instructions. After application of the

coating, the curing time was determined through measurement of the ability to successfully

process the coating as per the manufacturer’s recommended procedure. For these strippable

decontamination products, the first attempt to peel a decontamination coating was made 4 h post-

application. If not successful, three additional attempts were made at 18, 24 and 32 h post-

application.

The time to cure the strippable decontamination coating on dry, clean surfaces of stainless steel

and concrete coupons was determined for three commercially available decontamination

technologies. This report summarizes results for tests performed at one air change per hour

(ACH) of the experimental chamber (equal to an air flow of 9 cubic feet per hour [ft3/h]) under

six environmental conditions consisting of three temperatures selected within the 5-40 °C range

and two associated humidity values (20-80 %RH range). In addition, for each decontamination

technology, the curing time was also measured for one extra set of coupons that was pre-wetted

and kept at a specific temperature (20 °C), high humidity (80 % RH) condition. This pre-wetting

process was intended to simulate a rain shower prior to the application of the decontamination

product. Including this test point, the total test matrix performed at a normal ventilation rate

consisted of 21 measurements of the curing time.

Each test point consisted of a set of three concrete coupons and one stainless steel coupon as a

smooth surface reference material. For each test set, application and drying/curing of the coating

and the attempted processing was performed for two orientations of concrete coupons (two

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concrete coupons in vertical and one concrete coupon in horizontal position). For stainless steel

reference coupons, curing time assessments were performed for the vertical orientation only as

the anticipated more challenging orientation for curing.

2.1 Experimental Test Chamber A modified glove box was used as a test chamber to meet the environmental requirements of this

project. The decontamination chamber, shown in Figure 2-1, consisted of a modified glove box

with an internal volume of approximately 255 liters (L) (9.0 ft3). The exterior was insulated

using ½” TUFF-R, a rigid foil-clad polyisocyanurate board. Over an 8-h period, this chamber

was designed to be able to:

• Achieve RH values between 20-80 % and maintain them within ±5 % RH;

• Achieve temperatures between 5-40 ºC and maintain them within ± 3 ºC;

• Allow for the monitoring of RH and temperature conditions; and

• Allow for the coupons to be introduced and pulled out of the chamber through an airlock.

Figure 2-1. Decontamination chamber.

5

2.2 Environmental Controls

The associated schematics of the chamber are shown in Figure 2-2.

Legend:

Description Symbol/Device

Insulated Line

Plumbing

Electrical Signal

Vaisala HMD53 Temperature/Humidity Transmitter MT 101

Glove box Ambient Pressure Transmitter PT 101

HF-HBA Gas Humidity Bottle HC 101

Heated injection line Temperature Controller TC 101

Meter Box Flow Controller/Meter FC 101

Solenoid Valve for RH control V1

Solenoid relief valve for Glove box Ambient Pressure V2

Neslab RTE-100 recirculator VTLR

Universal Analyzers Inc. Sample Cooler (M/N-1090PV) Condenser Unit

Figure 2-2. Decontamination chamber schematics.

Temperature and RH in the decontamination chamber were measured using a Vaisala

HUMICAP® temperature and humidity sensor, model HMD53 (Vaisala, Inc.; Helsinki, Finland)

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(MT 101 in Figure 2-2). The humidity sensor was factory preset to measure 0 to 90 % (non-

condensing) RH. The temperature sensor was preset to measure from -20 to 60 ºC. This Vaisala

sensor is used for control of temperature and RH inside the glove box. The temperature inside

the glove box was also monitored by a type K thermocouple (OMEGA Engineering, Inc.,

Stamford, CT, USA) that would continuously sense temperatures from 0 to 1100 °C. Output

from the Vaisala RH/T sensor (MT-101 in Figure 2-2) and thermocouple were connected to an

IOTech data acquisition system (IOTech Inc.; Cleveland, OH, USA). Data from this IOTech

were collected by LabVIEW software (National Instruments Co., Austin, TX, USA). This

software was programmed to control temperature, RH, and glove box pressure.

2.2.1 Temperature Control A temperature- controlled fluid was flowing through a radiator and returned to a Neslab RTE-

100 recirculator (Neslab Instruments Inc., Portsmouth, NH, USA) which has both heating and

cooling capabilities that span the planned experimental temperature range of 5-40 °C. The

recirculator bath was controlled at a temperature from slightly above or below the target

temperature depending on the need to heat or cool the glove box to reach desired conditions. The

temperature inside the recirculator bath was monitored by a type K thermocouple (Omega

Engineering, Inc., Stamford, CT, USA). The test chamber temperature was controlled by

thermocouple output-controlled fans blowing the glove box atmosphere through a small radiator

mounted inside the glove box. When the temperature was too cold (when heating the glove box)

or too hot (when cooling the glove box), fans on the radiator inside the glove box were activated

by the software using a relay device. The cooling/heating fluid was recirculated at all times

during conditioning.

2.2.2 RH Control

To assist with low (20 %) RH conditions, air flow in the glove box was supplied by recirculating

the glove box air through a meter box (see Section 2.2.4). This meter box (FC 101 in Figure 2-2)

was pulling glove box air through a cylinder containing desiccant silica gel (Fisher Scientific,

Lane Fair Lawn, NJ, USA) and then Drierite™ (Hammond Drierite Co., Ltd.; Xenia, OH, USA)

to dry the glove box air (Figure 2-2) . This air flow was then pumped back into the glove box

7

after passing through a Peltier chiller (Model 1090PV, Universal Analyzer Inc., Carson City,

NV, USA). Recirculation was necessary to maintain cool and dry conditions. The recirculated air

bypasses the silica and Drierite™ when RH is below the set point to reduce the need to exchange

the media. A three-way solenoid valve (Norgren, Littleton, CO, USA) (V1 in Figure 2-2)

connected to a relay controls this bypass mechanism. Since water (vapor) is the main constituent

of the strippable coating that is released during the curing process while the humidity is

controlled, the term “air change” can be used to describe this setup despite the recirculating

process of the glove box air.

High (80 %) RH control was accomplished through the use of a high-flow gas humidity bottle,

model HF-HBA with Nafion® tubing (Fuel Cell Technologies, Inc.; Albuquerque, NM, USA)

(HC 101 in Figure 2-2). This device is labeled HC-101 in Figure 2-2. The gas humidity bottle

consisted of a heated vessel containing a length of Nafion® tubing submersed in water. Water

vapor passes through the walls of the Nafion® tubing and is picked up by passing air, which

leaves the gas humidity bottle 90 to 100 % saturated with water vapor.

2.2.3 Pressure Control

The static pressure of the glove box was controlled so that injection of the hot humid air did not

cause a positive pressure to build up in the chamber. This control was accomplished using a

differential pressure transducer (Model 265, Setra Systems, Boxborough, MA, USA) (PT-101 in

Figure 2-2) which compared the static pressure inside the glove box to ambient pressure in the

laboratory. When the differential pressures rose above 0.4 inches H2O, a solenoid connected

directly to the glove box atmosphere was opened by the LabVIEW software, which allowed the

pressure to equilibrate.

2.2.4 Aeration Rate Control

The aeration rate of the glove box was controlled by an Apex Instruments, Inc. (Fuquay-Varina,

NC, USA) XC-40 meter console (FC 101 in Figure 2-2). This meter box (FC 101 in Figure 2-2)

was equipped with a precision dry gas meter with a mechanical or digital display (model AP25,

0.7/rev. with digital gas volume totalizer, with Quadrature Encoder, 8 digit LCD Display; 1 cc

8

resolution) and mechanical orifice flow meter with 50 mm Minihelic® Pressure Gauge (range 0-

2" [0-50 millimeter (mm)] H2O).

2.2.5 Chemical Fume Hood for Decontaminant Preparation

Decontamination agents were prepared in a regular chemical fume hood. Environmental

conditions such as temperature and RH were monitored but not controlled. Environmental

conditions in the chemical fume hood were measured using a temperature and RH data logger

(HOBO U12 T/RH Data Logger, Onset Computer Corporation, Bourne, MA, USA). The

humidity sensor was factory-preset to measure 5 to 95 % RH while the temperature sensor was

preset to measure from -20 to 70 ºC.

2.3 Test Materials

The representativeness and uniformity of test materials are essential in achieving defensible

evaluation results. Material representativeness means that the materials are typical of those

currently used in interiors and exteriors of buildings in terms of quality, surface characteristics,

and structural integrity. In this effort, representativeness was assured by selecting test materials

(i.e., concrete and stainless steel) that are typical of those found in industrial and municipal

settings. All materials used in this project met industry standards or specifications for indoor

and/or outdoor use and were obtained from national suppliers.

Material uniformity means that all these material coupons are equivalent for purposes related to

testing. Uniformity was maintained by obtaining and preparing a quantity of test material

sufficient to allow multiple test samples to be prepared with intentionally uniform characteristics

(e.g., test coupons were prepared from the same starting materials, using the same preparation

procedure, as per EPA’s Decontamination Technologies Research Laboratory (DTRL) internal

operating procedure. The specifications of materials used for preparation of test coupons are

summarized in Table 2-1.

9

Table 2-1. Description of building materials for curing time testing.

Material Manufacturer/

Supplier Name Material specifications

Coupon Surface Size

L x W x H (inches) Material Preparation

Stainless

Steel McMaster-Carr

Multipurpose Stainless Steel (48"X48") type 304, #2B mill (unpolished, 0.036" thick)

6 x 6 x 1/8

Remove any lubricant/grease from shearing with acetone and wipe dry. Remove particles and dust by wiping clean with water and wipe dry.

Concrete

Lowe’s

hardware

store

Quikrete® Type I & II Portland Cement; Quikrete® All Purpose Sand

6 x 6 x 1.5

Remove particles by swiping with a soft nylon brush and DI* water. Allow to air dry on a laboratory bench for at least five days.

* Deionized

2.3.1 Coupon preparations

Heavy duty power hydraulic shears were used to cut the stainless steel coupons from larger

sheets to the correct length and width.

The concrete coupons were fabricated per internal operating procedure, using the commercially

available Quikrete® Type I & II Portland Cement, Quikrete® All Purpose Sand and DI water.

One batch of fifty (50) 6" × 6" coupons was created by mixing 67.9 lb Portland cement and

166.5 lb sand with 19.0 L of DI water. Each batch of concrete coupons was allowed to cure for at

least 30 days in a climate-controlled environment. Environmental conditions for the concrete

coupon storage area were measured using a temperature and RH data logger (HOBO U12 T/RH

Data Logger). The humidity sensor was factory-preset to measure 5 to 95 % RH.

Concrete coupons were labeled with a permanent marker on the side of each coupon. A pre-

printed label was also placed next to each coupon to aid in the identification of coupons and test

conditions on digital photographs.

10

2.4 Selected Decontamination Technologies

Specialty decontamination strippable coatings designed for decontamination of radionuclides

were used in this study. Decontamination agents are shown in Table 2-2. Three of the better

performing decontamination technologies for removal of radionuclides from concrete were

selected for this study. This selection was based on technology evaluations performed by EPA

through its National Homeland Security Research Center (NHSRC) (EPA 2011a, EPA 2011b,

EPA 2013a, EPA 2013b).

A description of the technology and its active ingredients as provided by the manufacturer of

each formulation is summarized in Table 2-2. The mechanism of action and other relevant

information regarding each decontamination agent, including special instructions for storage,

handling, as well as the preparation and application instructions and information on

recommended curing times, are described in detail in Sections 2.4.1 through 2.4.3.

Table 2-2. Decontamination agents and technologies used for curing times testing. Decon Agent Manufacturer/Supplier Name Technology Active Ingredients

CC Wet/CC Strip InstaCote, Inc.; Erie, MI, USA

Contamination control wetting agent/Strippable coating applied onto cured wetting agent

Water-Glycerin-non-ionic surfactants (wetting agent) and Vinyl-Acrylic-Latex (coating)

DeconGel® 1108 CBI Polymers, Inc.; Honolulu, HI, USA Strippable coating Proprietary

StripCoat TLC Free™ Bartlett Nuclear, Inc.; Plymouth, MA, USA Strippable coating

Vinyl-Acrylic- Polyisobutylene-Polyisoprene

2.4.1 InstaCote CC Wet/CC Strip

The InstaCote CC Wet/CC Strip product consists of two components. CC Wet is a water-based

wetting agent used to stabilize loose removable contamination on surfaces. This water-based

anti-dusting medium helps prevent airborne areas of contamination from occurring. The

application of wetting agent also aids capturing of contamination in crevices and pores. Here, CC

Wet was used as a pre-coat for the application of the stripcoat (CC Strip). CC Strip is a water-

based vinyl-acrylic-latex coating recommended for removal of loose radiological or other

11

hazardous contamination. CC Strip is typically applied over CC Wet. CC Strip re-hydrates the

CC Wet coating to encapsulate the contamination captured by the wetting agent. CC Strip is

applied as a liquid and cures to a clear, highly elastic coating which is removed by peeling.

2.4.1.1 Curing information provided by manufacturer for CC Wet/CC Strip

The manufacturer recommends a 24-h curing time for CC Strip to ensure that the product is fully

cured under the worst case environmental conditions (high humidity, low temperatures, no

ventilation). Per the manufacturer, a good indicator of sufficient curing would be a change in the

opacity of the coating - a coating that is ready for removal will become opaque while uncured

coating is translucent.

2.4.1.2 Application information CC Wet/CC Strip

The CC Wet and the CC Strip formulations are sold as ready-to-use products and do not require

any special preparation prior to application. The CC Strip was mixed with a paint stick prior to

use. As per manufacturer recommendation, the CC Wet was allowed to cure for 24 h to account

for the potential for excessive moisture formation on horizontal surfaces. The manufacturer

recommends a spray-on or roll-on/brush-on technique for application of CC Wet and CC Strip

onto contaminated surfaces. In this study, CC Wet was sprayed on using a 240 milliliter (mL)

adjustable spray wash bottle with an adjustable sprayer and allowed to dry for 24 h prior to

application of the CC Strip. The CC Strip was applied to the test coupons using the “brush-on”

technique developed in other research efforts using strippable coating decontamination agents

(EPA 2011a). The application was performed using a standard two-inch (5.0 cm) paint brush.

This paint brush was loaded with wet CC Strip by dipping the brush into the container of the

ready-to-use well mixed CC Strip. The coating was applied evenly over the entire surface of the

coupon. The brush was then used to smooth the applied CC Strip on each test coupon.

12

2.4.2 CBI DeconGel® 1108

CBI Polymers DeconGel® 1108 is a one-component, water-based, broad application, peelable

decontamination hydrogel coating designed for safely removing radioactive contamination or as

a covering to contain contamination. DeconGel® 1108 is recommended for decontamination of

radioisotopes as well as particulates, heavy metals, and water-soluble and insoluble organic

compounds, including tritiated compounds. When dry, the product locks the contaminants into a

polymer matrix. The film containing the encapsulated contamination can then be peeled and

disposed of according to appropriate local, state and federal regulations.

2.4.2.1 Curing information provided by manufacturer for DeconGel® 1108

According to the manufacturer, the DeconGel® 1108 drying time increases with wet film

thickness and can vary. Drying time depends on a combination of the ambient humidity,

temperature, type of substrate and applied wet film thickness. Curing can take from as little as an

hour for thinner coatings in a dry environment with considerable air flow, to overnight or longer

if thicker coats are applied in humid environments (e.g., thicker coats on porous concrete).

Drying times exceeding 24 h may be required for good peel performance on bare concrete, wood

and other highly porous substrates when thick films are applied in humid environments.

2.4.2.2 Application information for DeconGel® 1108

The DeconGel® 1108 is sold as a ready-to-use “paint-like” formulation and does not require any

preparation prior to application. For each test, a fresh portion of approximately 200 mL of

DeconGel® 1108 was transferred from the primary container to a test-specific container that was

then moved to the glove box. Per the manufacturer’s instructions, the DeconGel® 1108 may be

applied with a paint brush or trowel. For these tests, the DeconGel® 1108 was applied to the test

coupons using the “apply-dry-peel” technique developed in other research efforts (EPA 2011a,

EPA 2011b). In this method, the application was performed using a standard two-inch paint

brush. The paint brush was loaded with the decon gel by dipping the brush into a plastic

container containing the DeconGel® 1108 coating. Wet coating was applied generously until the

13

entire surface of the coupon was covered. The paint brush was then used to work the first layer

of wet coating into the surfaces. After the first application, the DeconGel® 1108 was allowed to

dry for 2 h, and a second coat was added on top of the initial coating following the same method.

2.4.3 Bartlett StripCoat TLC Free™

As per Bartlett Nuclear’s website (Bartlett 2010), their Stripcoat TLC Free™ is “a non-

hazardous nontoxic strippable coating designed for safely removing and preventing the spread of

radioactive contamination”. “While curing, Stripcoat TLC Free™ mechanically and chemically

entraps contamination.” The dried coating containing the encapsulated contamination can then be

peeled off the surface and disposed. Stripcoat TLC Free™ can also serve as a barrier to prevent

contamination from attaching to a surface or as a covering to contain contamination. Stripcoat

TLC Free™ should not be exposed to direct sunlight for long periods. Sunlight can damage the

coating, causing it to lose its strippable qualities. Stripcoat TLC Free™ is not a submersible

coating. However, some short-term exposure of the cured coating to water should not adversely

affect the coating's qualities.

2.4.3.1 Curing information provided by manufacturer for Stripcoat TLC Free™

Per manufacturer’s information, following the second application, the coating requires 4-10 h to

cure prior to removal. Curing times may depend on the coating thickness and humidity. Stripcoat

TLC Free™ can normally be removed after 4 h at normal room temperature. Thin applications

can cure in as little as one hour.

2.4.3.2 Application information Stripcoat for TLC Free™

The Stripcoat TLC Free™ is sold as a ready-to-use “paint-like” formulation and does not require

any preparation prior to application other than hand mixing prior to and during each use to

ensure homogeneity. Per manufacturer’s instructions, the Stripcoat TLC Free™ may be applied

with industrial spray equipment (preferred method), paint rollers or brushes. In this study, the

Stripcoat TLC Free™ was applied to the test coupons using the “apply-allow to dry-reapply”

14

technique developed in other research efforts (EPA 2011a, EPA 2013a). The application was

performed using a standard two-inch paint brush. The paint brush was loaded with wet Stripcoat

TLC Free™ by dipping the brush into a container containing the ready-to-use, well mixed

Stripcoat TLC Free™. The first coating was applied until the entire surface of the coupon was

covered. The brush was then used to smooth the applied Stripcoat TLC Free™ on each test

coupon. The second coating was applied after 2 h with the thickness of the final coat estimated as

1-2.5 mm, with a visible pattern of brush strokes.

2.5 Test Matrix The time required for the strippable decontamination coatings to cure on dry surfaces of stainless

steel and concrete coupons was determined for six environmental conditions consisting of three

temperatures (selected within the 5-40 °C range), two RH values (20-80 % range) at 1 ACH.

Since all decontamination products were water based, no efforts were made to include

temperatures below their respective freezing points. Manufacturer-provided freezing points

ranged from 27-28 °F (-3 °C) for the CC Strip and CC Wet products to 32 °F (0 °C) for Stripcoat

TLC Free™. A freezing point for CBI DeconGel® 1108 of 0 °F [sic] was noticed in the material

safety data sheet (MSDS) for this product. Actual freezing points of the decontamination

products were not determined in this study.

The high temperature of 40 ºC represents a frequently encountered mid-day high summer

temperature in the continental USA. Although higher temperatures can be observed, it is less

likely that a coating would be applied under such conditions considering the likely need to wear

personal protective equipment (PPE) for extended periods of time during the application of the

coating. Curing time assessments for wet surfaces were performed at 20 °C and 80 %RH at a

normal ventilation rate. The test matrix is shown in Table 2-3.

15

Table 2-3. Test matrix for each decontamination technology. Temperature

[°C]

RH

[%]

Target air flow

[ft3·h-1]*

Surface

characteristic

Concrete

vertical

Concrete

horizontal

Stainless steel

vertical

5 20 9 Dry 2 1 1

5 80 9 Dry 2 1 1

20 20 9 Dry 2 1 1

20 80 9 Dry 2 1 1

40 20 9 Dry 2 1 1

40 80 9 Dry 2 1 1

20 80 9 Wet 2 1 1

*Equivalent of a ventilation rate of 1 ACH.

Up to four attempts, as described in Section 2.8, were made per coupon to peel the

decontamination coating from the surface. A first attempt was made after 4 h followed by

attempts at 18 h, 24 h, and 32 h after application of the coating to the surface. If a peeling

attempt was successful from all four coupons after a specific time, the test for that coating at that

environmental condition was considered to be completed. The overnight drying of these coatings

was in general expected to be sufficient for complete curing based on previous research efforts

for concrete material coupons and environmental conditions with temperatures between 19 and

21 °C and the RH between 20 and 22 % (EPA 2011a).

2.6 Preparation of Coupons for Testing

Prior to the coating application, the surface of each coupon was examined for obvious cracks or

abnormalities and, if none were found, the coupon surfaces (both concrete and stainless steel)

were cleaned with a soft nylon brush and DI water and allowed to air dry on a laboratory bench

for at least five days. Labeled coupons were then moved to the test chamber/glove box that was

set at the specific set of temperature/RH/air change conditions.

16

After a conditioning period of at least 48 h (up to 72 h if the equilibration phase included a

weekend) to allow equilibration between the coupon material temperature and the glove box

temperature and RH, the decontamination coating was applied to the test coupons. Figure 2-3

shows a set of coupons assembled for testing.

Figure 2-3. Coupons assembled for testing.

2.6.1 Wetted coupon preparation

For the wet surface testing, the sides and bottom of each concrete coupon were sealed with

water-based epoxy resin concrete sealer (StoneLok™ E3, Richard James Specialty Chemicals

Corp., Hastings-On-Hudson, NY, USA) to avoid penetration of water from the sides or bottom.

The sealant was allowed to cure for at least 72 h. Stainless steel coupons were not sealed.

Coupons for wet surface testing underwent a 48-h long equilibration at 20 ºC/80 % RH. The

wetting procedure was performed after this equilibration phase in the glove box was finished.

Tap water, used for wetting of coupons was sprayed on the coupon with a 240 mL volume

adjustable spray wash bottle made of high-density polyethylene equipped with an adjustable

polypropylene sprayer. The amount of water needed for complete wetting of the coupon surface

was set to reflect a weather condition corresponding to a very heavy rain fall rate of

approximately 20 mm per hour for half an hour, i.e., approximately 230 mL of water was

sprayed onto each 6" × 6" coupon.

17

Each of the to-be-wetted coupons was placed in an individual container of known weight with

the unsealed surface facing up. Each coupon was set on four rubber spacers to isolate the

concrete material from any potential run-off water to be collected in the container. After the

water spray/simulated rainfall was applied, coupons were allowed to stay in a horizontal

orientation for 15 minutes (min), to allow absorbing of water by the unsealed top surface of

concrete. Figure 2-4 shows an example of a concrete coupon soaking up the water after

application of the simulated rainfall (top view on the left and side view on the right).

Figure 2-4. Top- and side-view of concrete coupon soaking up the water after application of the simulated rainfall. After 15 min, all concrete coupons were turned to vertical orientation and placed on two rubber

spacers of sufficient size to allow the run-off of any excess water. The wet coupons were then

immediately moved to the glove box, and after one hour of equilibration time (at 20 ºC/80 %

RH), the decontamination coating was applied to the test coupons. Based on observed changes in

RH in the glove box, these coupons were saturated with water. Containers were weighed to

calculate the amount of simulated rain in mL that ran off from the coupon surface. Table 2-4

summarizes the amounts of water applied onto and absorbed by concrete coupons in the

simulated rainfall procedure.

18

Table 2-4. Simulated rainfall parameters. Simulated rainfall parameters Average [mL/coupon] ± SD*; number of coupons

Amount of water applied 229 ± 2.5; n = 16

Average run-off volume 188 ± 10; n = 16

Average amount of water absorbed by concrete coupon 41 ± 10; n = 16

* SD: Standard Deviation

2.7 Preparation and Application of the Decontamination Agents

Decontamination products were prepared and applied per manufacturer’s instructions, with

emphasis given to realistic application procedures that could be expanded to larger surface areas.

A fresh batch of coating/gel was used for each test. Immediately prior to testing, a small amount

of the coating/gel was prepared in a clean plastic container. The container was weighed and the

weight was recorded in the laboratory notebook. This preparatory work was performed in the

chemical fume hood to satisfy health and safety concerns related to working with the coating (i.e.

appropriate ventilation, respiratory protection). Environmental conditions in the chemical fume

hood were measured using a HOBO U12 T/RH data logger.

The ready-to-use batch of freshly prepared coating material was then transferred from the

chemical fume hood to the glove box using the modified airlock. The coating/gel was applied per

manufacturer’s instructions inside the modified glove box under the specified T and RH

conditions maintained in the glove box. The sequence in which the coating/gel was applied to the

test coupons was recorded so that the sequence could be repeated in the coating removal

procedure at the end of the curing period.

2.7.1 Decontamination Coating Amounts The amount of coating used for each application was assessed gravimetrically by weighing the

test container with coating material before application and then immediately post-application of

the (double) coating to the entire test set of four (one stainless steel and three concrete) coupons.

The loading volume per surface area [liter (L)/m2] for each set was calculated based on the mass

19

[kg] and specific gravity [kg/L] of each coating applied onto the total test surface area of 4 × 36

square inches (= 144 square inches [0.0929 m2]). Loading volumes were adjusted for the amount

of coating that remained on the brush post application. The remaining amounts on the brush were

calculated from a series of gravimetric measurements of pre- and post-application weights of

brushes [kg] used for coating applications and the specific gravity of each coating.

Test-specific loading volumes for each coating varied across tests and are shown in Figures A-1

through A-3 in Appendix A and Table B-3, B-7, and B-11 of Appendix B. The average loading

volumes for each coating/gel are given in Table 2-5.

Table 2-5. Average loading volumes per surface area for decontamination coatings tested.

Decon Agent Average loading volumes per surface areaa

[L/m2, ± SD]; n=number of measurements

CC Wet 0.36 ± 0.10; n = 7

CC Strip 0.48 ± 0.11; n = 7

DeconGel® 1108 1.10 ± 0.22; n = 7b

StripCoat TLC Free™ 0.35 ± 0.10; n = 7b

a Loading volumes were adjusted for average amount of coating that remained on brush post-application. b Double coating applied.

The application of these decontamination products by sprayer was not considered as part of this

study. Any potential differences in curing time between application by brush or sprayer due to

differences in the amount applied per surface area would require additional testing.

Application of these water-containing coatings in the glove box resulted in high humidity

spikes/periods for all tests. The recorded RH profiles during post-application of coatings (i.e.,

during the curing phase) are shown in Appendix C, in Figures C-1 through C-3. Such RH spikes

may be exaggerated here by the relatively small volume of the glove box. However, it is likely

that increases in RH following application would also occur in smaller interior areas with low air

change rates.

20

2.8 Procedure to Determine Curing Status

The first attempt to peel off a coating from the coupon surface was made in the lower right

corner of each coupon (Corner 1 in Figure 2-5) at 4 h post-application. Prior to the first peeling

attempt, a slight surface cut at a 45 degree angle was performed with a utility knife to

start/facilitate the removal of the coating. The peel was started at this score line, moving towards

the center of the test coupon. If the first peel-off attempt was unsuccessful, the following

attempts to peel off the coating were performed starting with the upper right corner, then upper

left corner, then lower left corner of each coupon (corners 2, 3 and 4 in Figure 2-5). This curing

assessment process was conducted for all three strippable coatings.

Coupons were allowed to dry for 4 h before the first attempt to peel off the coating was made.

The second attempt (if needed) was performed after an overnight (18 h) curing. A third attempt

was scheduled at 24 h and, if needed, a fourth at 32 h post-application.

Figure 2-5. Scheme of the successive attempts to peel off decontamination coating from coupon surface.

2.9 Curing Status Definitions

Based on the strippable coating/gel design, decontamination of a building material can be

expected to be successful only when a coating can be removed in its entirety from the surface as

the coating would capture the radionuclides. Efforts to remove incompletely cured coatings

1

2 3

4

21

would lead to lower decontamination factors. Four definitions of the curing status at a specific

time post application were identified as follows:

1. Excellent curing: Coating was successfully removed from the coupon in one piece,

2. Good curing: Coating was successfully removed from the coupon in several smaller

sections without leaving non-cured coating material on the surface,

3. Partial curing: Coating could only be removed partially as localized wet spots (not cured)

were present or the peeling process resulted in numerous small (dried out) pieces, and

4. No curing: Removal of coating was not possible due to the wet nature of the coating.

22

3.0 Test Results and Discussion

3.1 CC Wet/CC Strip

The average coating thickness post-application was estimated to be less than 2 mm. The CC

Wet/CC Strip coating cured at 4 h post-application for all environmental conditions, with a

single exception of the stainless steel surface at 20 °C/80 %RH/1 ACH/dry surface test, where

curing occurred after overnight processing (23 h post-application). This resulting coating was

overly dried-out and showed signs of elasticity loss. The coating chipped off during removal (see

Figure 3-1). Similar “brittle” coatings were observed for the 5 °C/20 %RH/1 ACH/dry surface

test. The brittleness may be due to slightly lower loading volumes observed for CC Strip

applications at cold temperatures (Figure A-2, Appendix A). The 5 °C/80 %RH/1 ACH/dry

surface test had the lowest loading volume amongst all tests using the same brush on procedure,

resulting in more inelastic and thinner yet strippable coating, which did come off the coupon

surface in many small pieces as shown in Figure 3-2), suggesting that higher humidity may

protect the lower-loading-volume coatings from over drying over long periods of time and

prevent the consequent brittleness of the resulting coatings. The application of a thicker coating

at low temperature might have improved the ability to remove the coating as one piece. This was

not investigated further in this study.

Figure 3-1. Appearance of the overly dried-out CC Wet/CC Strip coating (5 °C/20 %RH/1 ACH/dry surface, 4 h post-application of CC Strip coat).

23

Figure 3-2. Several-piece-removal of CC Wet/CC Strip coating (20 °C/80 %RH/1 ACH/dry surface; 4 h post-application of CC Strip coat).

Figures 3-3 and 3-4 show examples of the CC Wet/CC Strip coating curing that could be removed

completely as one elastic piece from stainless steel and concrete, respectively.

Figure 3-3. One-piece-removal of CC Wet/CC Strip coating from stainless steel (40 °C/20 %RH/1 ACH/dry surface; 4 h post-application of CC Strip coat).

24

Figure 3-4. One-piece-removal of CC Wet/CC Strip coating from concrete (40 °C/20 %RH/1 ACH/dry surface; 4 h post-application of CC Strip coat). Table 3-1 summarizes the results of the CC Wet/CC Strip curing time assessment under all

environmental conditions tested for 1 ACH for dry- and wet-surface tests.

25

Table 3-1. Assessment of CC Wet/CC Strip curing times with opacity rating of coating under various environmental conditions with normal ventilation.

Test conditions

Assessments of curing process

[h post-application]

Stainless steel vertical

Concrete vertical # 1


Concrete horizontal # 1

5 °C/20 %RH test/1 ACH/ dry surface

4 OPAQUE CHIPPED PIECES

OPAQUE CHIPPED PIECES



18 24 32


4 SEMI-TRANSLUCENT SEVERAL PIECES

SEMI-TRANSLUCENT SEVERAL PIECES



18 24 32


4 OPAQUE SEVERAL PIECES

OPAQUE SEVERAL PIECES



18 24 32


4 SEMI-TRANSLUCENT WET




23* SEMI-TRANSLUCENT

CHIPPED PIECES 24 32


4 OPAQUE ONE PIECE


OPAQUE ONE PIECE

OPAQUE ONE PIECE

18 24 32


4 SEMI-TRANSLUCENT ONE PIECE

SEMI-TRANSLUCENT ONE PIECE



18 24 32

20 °C/80 %RH test/1 ACH/ wet surface

4 SEMI-TRANSLUCENT SEVERAL PIECES




18 24 32

* delayed second attempt LEGEND:

DESCRIPTION excellent curing/complete removal in one piece. DESCRIPTION good curing/complete removal in several pieces. DESCRIPTION partial curing/partial removal.

DESCRIPTION no curing/no removal possible.

26

3.2 DeconGel® 1108 Average coating thickness post-application was estimated to be less than 2 mm. For most of the

environmental conditions tested, the DeconGel® 1108 required at least overnight processing (see

Table 3-2), and resulted in easily strippable one-piece coatings, as shown in Figures 3-5 and 3-6.

Figure 3-5. One-piece-removal of DeconGel® 1108 coating from stainless steel (5 °C/80 %RH/1 ACH/dry surface, 18 h post-application of 2nd coat).

Figure 3-6. One-piece-removal of DeconGel® 1108 coating from concrete (5 °C/80 %RH/1 ACH/dry surface, 18 h post-application of 2nd coat). The 20 ºC temperature and high humidity (80 %RH) conditions resulted in non-strippable (wet

or semi-cured) coatings at all four time points tested on all surfaces/surface orientations tested

for a dry surface.

27

The coating was eventually successfully peeled off at 48 h post-application (data not shown). In

contrast, the coating did cure overnight when applied to the wet surface for the 20 °C/80 %RH/1

ACH test condition (Table 3-2). The semi-curing observed for the test on the dry surface may be

attributed to a very high-humidity spike (>90 %) related to a software malfunction and the

consequent deficiencies of environmental controls of the experimental chamber. The extremely

high humidity lasted overnight (as shown in Figure C-2 in Appendix C) and may have prevented

the coating from a complete curing due to condensation inside the chamber. Figure 3-7 shows an

example of the semi-cured DeconGel® 1108 coating, when removal of the coating was possible

only from a portion of the tested surface.

Figure 3-7. Partial removal of semi-cured DeconGel® 1108 coating (20 °C/80 %RH/1 ACH/dry surface, 32 h post-application of 2nd coat). The 5 °C/80 %RH/1 ACH condition resulted in a wet or almost cured gel at the 4 h post-

application time point (Table 3-2). This “almost cured” coating was defined as a gel that was

starting to cure, but could not be removed, even partially as shown in Figure 3-8.

28

Figure 3-8. Almost-cured DeconGel® 1108 coating (5 °C/80 %RH/1 ACH/dry surface, 4 h post-application of 2nd coat). The DeconGel® 1108 cured at 4 h (Table 3-2) for all humid and hot conditions in line with the

manufacturer’s information that heat can reduce the drying times of the DeconGel® 1108,

especially in humid environments.

Table 3-2 summarizes the results of the DeconGel® 1108 curing time assessments under all

environmental conditions tested for 1 ACH for dry and wet surface tests.

29

Table 3-2. Assessment of the DeconGel® 1108 curing times under various environmental conditions with normal ventilation.

Test conditions

Assessments of curing process

[h post-application]






4 WET WET WET WET 18 ONE PIECE ONE PIECE ONE PIECE ONE PIECE 24 32


4 WET ALMOST CURED ALMOST CURED ALMOST CURED 18 ONE PIECE ONE PIECE ONE PIECE ONE PIECE 24 32


4 ONE PIECE ONE PIECE ONE PIECE ONE PIECE 18 24 32


4 WET WET WET WET 18 WET SEMI-CURED SEMI-CURED SEMI-CURED 24 SEMI-CURED SEMI-CURED SEMI-CURED SEMI-CURED 32 SEMI-CURED SEMI-CURED SEMI-CURED SEMI-CURED




4 WET STICKY STICKY STICKY 18 ONE PIECE ONE PIECE ONE PIECE SEVERAL PIECES 24 32

20 °C/80 %RH test/1 ACH/ wet surface

4 WET ALMOST CURED ALMOST CURED ALMOST CURED 18 ONE PIECE ONE PIECE ONE PIECE ONE PIECE 24 32

LEGEND: DESCRIPTION excellent curing/complete removal in one piece.

DESCRIPTION good curing/complete removal in several pieces. DESCRIPTION partial curing/partial removal. DESCRIPTION no curing/no removal possible.

30

3.3 Stripcoat TLC Free™ Assessments of the curing process were performed 4 h post-application of the second coat; no

additional assessments were needed. Stripcoat TLC Free™ produced easily strippable coatings

under all environmental conditions tested at 1 ACH, both on dry and wet surfaces (Table 3-3).

Figures 3-9 and 3-10 show removal of cured Stripcoat TLC Free™ from a concrete and a

stainless steel coupon, respectively. Table 3-3 summarizes the results of the Stripcoat TLC

Free™ curing time assessments under all environmental conditions tested for a normal

ventilation scenario (1 ACH) for dry and wet surface tests.

Figure 3-9. One-piece-removal of Stripcoat TLC Free™ coating from concrete (20 °C/20 %RH/1

ACH/dry surface, 4 h post-application of 2nd coat).

Figure 3-10. One-piece-removal of Stripcoat TLC Free™ coating from stainless steel (20 °C/20 %RH/1 ACH/dry surface, 4 h post-application of 2nd coat).

31

Table 3-3. Assessment of the Stripcoat TLC Free™ curing times under various environmental conditions with normal ventilation.

Test conditions Assessments of curing

process [h post-application]





5 °C/20 %RH test/1 ACH/ dry

surface



surface



surface



surface



surface



surface


20 °C/80 %RH test/1 ACH/ wet

surface


LEGEND: DESCRIPTION excellent curing/complete removal in one piece.

DESCRIPTION good curing/complete removal in several pieces. DESCRIPTION partial curing/partial removal. DESCRIPTION no curing/no removal possible.

32

4.0 Quality Assurance and Quality Control

4.1 Data Quality Objectives

The objective of the experiments was to determine curing times for various strippable coatings

used for decontamination of radionuclides on a representative building material in the urban

environment under various environmental conditions (a combination of temperature, RH and air

change rate).

Critical measurements required to fulfill this objective included:

• RH and temperature measurements during the curing process of decontamination

coatings.

• Air change rate of the test chamber.

• Time lapse between application and actual curing of decontamination coating (for up to

four coating removal attempts within 4 – 32 h post-application of the coating).

Non-critical measurements were:

• RH and temperature measurements during curing (aging) process of concrete coupons.

• Concrete coupon curing/aging time (minimum of 30 days under normal laboratory

conditions).

• RH and temperature in fume hood as used during preparation of decontamination

coatings.

4.2 Data Quality Indicators

Data quality indicators (DQIs) for the critical measurements used to determine if the collected

data met the quality assurance (QA) objectives are summarized in Table 4-1.

33

Table 4-1. DQIs for critical measurements.

Measurement Parameter Analysis Method Accuracy Precision/ Repeatability

Differential time Stop watch 1 s 1s

RH Vaisala probes ±3 % RH* 2 % RH

Temperature Vaisala probes ±0.4 °C** 0.1 °C

Temperature Thermocouple ±1.5 °C*** NA

Air Change Rate Dry Gas Meter 1 mL**** 15L/h (6 % of 1 ACH)

* For 0-90 % RH range; ** For 0-40 ºC range; *** For 40-375 ºC range; **** For range 0-2 inches Hg (0-50 mm H2O).

4.3 Equipment Calibrations

The equipment used to make the critical measurements was maintained and calibrated prior to

use. The method of calibration as well as the frequency of calibration is listed in Table 4-2.

Table 4-2. Equipment calibration schedule. Equipment Frequency

Stop watch As specified by manufacturer in a Certificate of Calibration (NIST* traceable re-certification)

Vaisala Probe (T, RH) Yearly/biweekly checks**

Thermocouple Yearly

HOBO U12 T/RH data logger Prior to aging of each batch of coupons

Meter Box Yearly

* National Institute of Standards and Technology. ** Calibration checks every week according to internal operating procedures.

4.4 Quantitative Acceptance Criteria

34

The quantitative acceptance criteria for each critical measurement as established in the Quality

Assurance Project Plan (QAPP) prior to the curing tests are shown in Table 4-3. The percent

completeness of the data set for each test is defined as the ratio of the number of data points

taken that pass the acceptance criteria for the critical measurements to the total number of data

points taken, multiplied by 100 %.

Table 4-3. Acceptance criteria for critical measurements.

Measurement Parameter Target Values Precision Completeness %

Curing time/times of strippable coatings

Time points (4 h, 18 h, 24 h and 32 h)

± 5 min 100

Chamber Temperature 5, 20, 40 °C ± 3 °C 90

Chamber RH 20, 80 % ± 5 % 90

Chamber aeration rate 9 ft3/h ± 6 % 90

Test specific results for all critical and non-critical measurements performed for the curing time

assessments are given in Appendix B (Table B-1 through B-12). A summary is given in Table 4-

4 below.

35

Table 4-4. Summary of critical measurements and completeness of data. Measurement

Parameter Target Values Average measured

for individual tests; n = number

of tests

Number of tests below acceptance criteria out of total number of tests

Curing time/times of strippable

coatings

Time point 1 (4 h post-application)

4 h 00 min 07 sec; n = 21

0/21


18 h 47 min 06 sec; n = 6

1/6a


23 h 58 min 49 sec; n = 1

0/1


31 h 58 min 04 sec; n = 1

0/1

Chamber Temperature

5 °C 7.4 °C; n = 6 2/6b

20 °C 20.6 °C; n = 9 0/9

40 °C 39.7 °C; n = 6 2/6c

Chamber RH 20 %RH 20.6 %RH; n = 9 2/9d

80 %RH 80.1 %RH; n = 12 2/12e

Chamber aeration ratef 9 ft3/h

9.5; n = 21 // 9.4; n = 4

10/21 // 1/4g

a One 18 h time point was at 4 AM local time and assessment was postponed for this CC Wet/CC Strip test to more practical time, approximately 23 h post-application (Table B-4). b Two test conditions had average temperatures of 8.3 and 8.5 °C (see Tables B-1 and B-9). c Two test conditions had average temperature of 37.7 and 39.9 °C (see Tables B-5 and B-9). d Two test conditions had average RH of 20.0 and 23.8 % RH (see Tables B-6 and B-10). e One test condition had average RH of 82.9 % RH (see Table B-10). f Prior to- // post-application of decontamination coating values; air flow measurements calculated for time periods varying from 0.02 to120 h; test specific air flows are in Appendix B, Tables B-3, B-7, and B-11. g Ten test conditions were conducted with flow rates as low as 6.4 and as high as 14.7 ft3/h (0.7 – 1.6 ACH). The temperature and RH conditions were recorded in real-time using a portable data acquisition

(PDAQ) system and LabView software. For some tests, sporadic periods without control of

environmental conditions and/or without temperature and RH data acquisitions were observed. A

specific reason for these problems was not identified, but it was attributed to the intermittent

malfunction(s) of the software or hardware (laptop, data acquisition system). The impact of the

periodic lack of environmental controls was typically low, with RH and T holding within their

respective acceptance criteria (as determined after the restart of data acquisition). For some tests,

however, the lack of environmental controls resulted in conditions that were outside the

36

acceptable T and/or RH range. These periods were assumed to be entirely outside the acceptance

criteria in the completeness of data calculations.

For the air flow measurements, once coupons were placed in the glove box for equilibration, the

meter box was set to a flow rate of 9 ft3/h representative of 1 ACH by adjusting the fine adjust

metering valve on the unit. Initial flow rates were calculated based on the air volume sampled in

2.0 min. Adjustments to the metering valve were made until the flow rate was equal to 0.3

ft3/min (= 9 ft3/h). Once the flow was set, it was recorded only intermittently. For most of the

testing, the flow would not have changed past this point and only minor changes would have

been made to the setup. However, sometimes the flow was increased substantially to “purge” the

glove box environment after the RH fell outside the acceptance criteria, e.g., after a software or

hardware malfunction. Initially, these changes were not completely documented, and they could

have had an effect on the actual flow before testing began, or – if the meter box flow

measurement was not reset after the purge, it could result in the exaggeratedly high average flow

(as calculated prior to curing time assessments). Additional flow measurements were introduced

later on in the project as a standard procedure, with flow being verified and recorded prior to the

equilibration, post-equilibration/prior to the coating application, post-application/during the

curing process, and at the end of the entire test. For tests with multiple flow measurements (n =

4), the air change rates measured before equilibration, after equilibration and during/after curing

varied by less than 20 %, with coefficients of variation of less than 10 % for flow measurements

taken for each individual test. These observations suggest that the average flow values recorded

initially just after equilibration would have reflected the flow rates during the coating curing

process accurately.

4.5 Amendments and deviations from the original QAPP

4.5.1 Formal Amendments

During the course of this study, one amendment was added to the QAPP in response to the

observed experimental difficulties of maintaining some of the environmental conditions at 1

37

ACH. Minor edits were also captured in this amendment. This amendment was submitted to the

EPA QA officer for formal approval.

4.5.2 QAPP Deviations

Deviation 1:

The original test matrix included a fourth decontamination product, a decontamination gel that

does not form a strippable coating against radionuclides. Due to a systematic error in the

preparation of smaller volumes of this product, the product as generated contained approximately

20 % more water than per the manufacturer’s instructions. This error was observed during the

quality control (QC) near the end of this study. Since water content is likely to drive observations

on whether a coating or gel cures, the curing results for this decontamination product were

excluded from this report.

Deviation 2:

The original test matrix included test conditions with no air flow present in the modified glove

box to simulate a stagnant air situation. Due to complications in maintaining environmental

conditions with one air change for extended (multiple days) periods of time, this part of the study

was not conducted at this time.

38

5.0 Summary

The decontamination products evaluated in this study are intended for large-area in situ removal

of a wide spectrum of radionuclides, even under challenging environmental conditions. All

strippable decontamination coatings tested (InstaCote CC Wet/CC Strip, CBI Polymers

DeconGel® 1108 and Bartlett Nuclear StripCoat TLC Free™) were easy to apply, with no

requirement for pre-preparation processes. None of the products posed major challenges during

the application using the brush-on technique employed in this study. The loading volumes per

surface test area were dependent on humidity and to a lesser extent on temperature.

The curing process of these coatings was tested under various environmental conditions. The

curing was very rapid under mild/warm (20 ºC/40 ºC) temperatures and low humidity (20 % RH)

conditions when all coatings tested were strippable at 4 h post-application. The surface

characteristics (wet versus dry) did not cause differences in the curing process, but high humidity

and cold temperatures seemed to be drivers for prolonged curing times for some strippable

coatings (e.g., DeconGel® 1108 and CC Wet/CC Strip). No measurable differences in the curing

times of these coatings were observed when applied to vertical surfaces versus horizontal

surfaces.

The observed curing of CC Wet/CC Strip always occurred within 24 h post-application - the time

period recommended by the manufacturer for processing of this coating at the worst case

environmental conditions (high humidity, low temperatures, no ventilation). The removal of this

coating at 5 ºC and 20 % RH was more difficult due to the dried out nature and loss in elasticity

of the coating after 4 h. This observation may be somewhat biased by the lower amount of the

coating material that was applied using the same brush on procedure resulting in a thinner than

recommended coating layer that would be more difficult to remove. An application of a second

layer of CC Strip may facilitate the removal of the coating under those conditions.

For DeconGel® 1108, the observed overnight or longer curing times are in line with the

recommended curing time by the manufacturer for decontamination scenarios where thicker

39

coatings are applied in humid environments when drying times exceeding 24 h may be required

for good peel performance.

StripCoat TLC Free™, which has the shortest manufacturer-recommended curing times (4-10 h)

amongst all strippable coatings tested, formed strippable coatings at 4 h post-application under

all environmental conditions tested.

The information presented in this report should help EPA responders or On-Scene Coordinators

(OSCs) in the field in identifying conditions under which strippable coatings may not cure as fast

as one may expect based on curing times at normal room temperature conditions. The curing

times and identification of more challenging conditions leading to longer curing times by the

manufacturers of these products are consistent with the observations in this report under the

tested environmental conditions.

40

6.0 References

Bartlett (2010). Stripcoat TLC Free™ product information,

http://www.bartlettnuclear.com/producs-technology-contamination-control-coatings-stripcoat-

tlc.htm. Last accessed June 2014.

EPA 2011a. Evaluation of Nine Chemical-Based Technologies for Removal of

Radiological Contamination from Concrete Surfaces. EPA Technical Brief. Cincinnati, OH,

USA. National Homeland Security Research Center Office of Research and Development, U.S.

Environmental Protection Agency.

EPA 2011b. CBI Polymers DeconGel® 1101 and 1108 for Radiological Decontamination.

Technology Evaluation. Cincinnati, OH, USA, EPA Report 600/R-11/084. National Homeland

Security Research Center Office of Research and Development, U.S. Environmental Protection

Agency.

EPA 2013a. Bartlett Services, Inc. Stripcoat TLC Free™ Radiological Decontamination of

Americium. Technology Evaluation. Cincinnati, OH, USA. EPA Report 600/R-13/005. National

Homeland Security Research Center Office of Research and Development, U.S. Environmental

Protection Agency.

EPA 2013b. Development of Standard Test Methods and Evaluation of the Shelf Life and

Weatherability of Fixative Coatings for Control of Radiological Contamination. EPA Report

600/R-13/233. Research Triangle Park, NC, USA. National Homeland Security Research Center

Office of Research and Development, U.S. Environmental Protection Agency.

http://www.bartlettnuclear.com/producs-technology-contamination-control-coatings-stripcoat-tlc.htm

http://www.bartlettnuclear.com/producs-technology-contamination-control-coatings-stripcoat-tlc.htm

41

Appendix A: Loading volumes versus environmental conditions

42

Figure A-1. Loading volumes for CC Wet applications under different environmental conditions

Figure A-2. Loading volumes for CC Strip applications under different environmental conditions

0.0

3.0

6.0

9.0

12.0

15.0

0 5 10 15 20 25 30 35 40 45

Coat

ing u

sed

for a

pplic

atio

n [m

L/co

upon

]

T [°C]

CC Wet loading volumes

20% RH dry surface tests 80% RH dry surface tests 80% RH wet surface test

5.0

8.0

11.0

14.0

17.0

20.0

0 5 10 15 20 25 30 35 40 45

Coat

ing u

sed f

or ap

plica

tion [

mL/

coup

on]

T [°C]

CC Strip loading volumes

20% RH dry surface tests 80% RH dry surface tests 80% RH wet surface test

43

Figure A-3. Loading volumes for DeconGel® DG1108 applications under different environmental

conditions.

Figure A-4. Loading volumes for Stripcoat TLC Free™ applications under different environmental

conditions

10

20

30

40

0 5 10 15 20 25 30 35 40 45

Coat

ing u

sed f

or ap

plica

tion [

mL/

coup

on]

T [°C]

Decon Gel DG1108 loading volumes

20% RH dry surface tests 80% RH dry surface tests 80% RH test wet surface

0.0

3.0

6.0

9.0

12.0

15.0

0 5 10 15 20 25 30 35 40 45

Coat

ing u

sed

for a

pplic

atio

n [m

L/co

upon

]

T [°C]

StripCoat TLC loading volumes

20% RH dry surface tests 80% RH dry surface tests 80%RH wet surface test

44

Appendix B: Critical and non-critical measurements

45

Table B-1. Temperatures prior and post-application of CC Wet/CC Strip.

Test Temperature [ºC] measured during equilibration/pre-application

Temperature [ºC] measured during curing/post-application

Mean ± SD Range % completeness Mean ± SD Range 5 °C/20 %RH test/dry surface 7.3±0.10 7.06-7.53 100 7.4±0.18 7.1-12.3 5 °C/80 %RH test/dry surface 8.3±0.13 7.5-8.7 0.01 7.5±0.56 7.1-9.8 20 °C/20 %RH test/dry surface 19.9±0.10 19.8-20.0 100 19.2± 0.40 18.7-20.0 20 °C/80 %RH test/dry surface 19.7±0.14 19.4-20.0 100 18.2± 0.54 17.7-20.0 40 °C/20 %RH test/dry surface 40.0±0.02 39.9-40.3 100 40.0 ± 0.016 39.8-40.1 40 °C/80 %RH test/dry surface 40.0±0.60 35.6-44.1 98 40.1 ± 0.10 40.0-40.3 20 °C/80 %RH test/wet surface 21.6±0.10 21.5-21.9 100 21.6±0.12 21.5-22.1

Table B-2. RH conditions prior and post-application of CC Wet/CC Strip.

Test RH [%] measured during equilibration/pre-application RH [%] measured during curing/post-application

Mean ± SD Range % completeness Mean ± SD Range 5 °C/20 %RH test/dry surface 19.1±0.29 18.4-20.0 100 28.5±7.1 19.1-58.2 5 °C/80 %RH test/dry surface 79.1±0.52 77.8-84.9 100 82.2±1.3 75.5-83.2 20 °C/20 %RH test/dry surface 20.7±1.3 19.6-25.2 100 43± 9.8 19.6-73.6 20 °C/80 %RH test/dry surface 80.1±0.20 78.1-81.3 100 84± 2.4 79.5-90.8 40 °C/20 %RH test/dry surface 20.1±0.10 20.0-21.1 100 25.1±10 19.4-69.5 40 °C/80 %RH test/dry surface 80.4±1.2 74.1-93.9 94 80.0±0.50 78.6-82.9 20 °C/80 %RH test/wet surface 79.0±0.02 79.0-79.1 100 88.3±9.9 78.9-122a

a Condensing environment; incorrect reading Vaisala probe at 100 % RH Table B-3. Other parameters for application of CC Wet/CC Strip.

Test Air flow during equilibration

and post-application [ft3/h/% of target ventilation

rate]

Average amount of CC Wet used for application [mL/coupon]

Average application rate of CC Wet

[sec per coupon, ± SD

Average amount of CCStrip used for application [mL./coupon]

Average application rate of CCStrip

[sec per coupon, ± SD]

Final coating thickness

[mm]

5 °C/20 %RH test/dry surface 10.0 / NA 111 / NA 8.1 0:00:12 0:00:04 11.8 0:00:39 0:00:02 1.1-2.5 5 °C/80 %RH test/dry surface 8.4 / NA 94 / NA 7.4 0:00:13 0:00:01 9.8 0:00:39 0:00:04 1.1-2.5 20 °C/20 %RH test/dry surface 10.9 / NA 121 / NA 11.0 0:00:13 0:00:01 13.8 0:00:35 0:00:02 1.1-2.5 20 °C/80 %RH test/dry surface 13.4 / NA 148 / NA 8.4 0:00:15 0:00:04 15.3 0:00:42 0:00:01 1.1-2.5 40 °C/20 %RH test/dry surface 9.2 / NA 102 / NA 10.0 0:00:21 0:00:01 16.8 0:00:41 0:00:01 1.1-2.5 40 °C/80 %RH test/dry surface 8.2 / NA 91 / NA 5.0 0:00:20 0:00:03 12.5 0:00:43 0:00:03 1.1-2.5 20 °C/80 %RH test/wet surface 9 / 9.4 100 / 104 7.9 0:00:14 0:00:01 10.5 0:00:35 0:00:06 0.9-1.1

NA – not available

46

Table B-4. Curing time assessments for CC Wet/CC Strip.

Test Average curing time, 1st attempt to peel off

[h:min:sec post-application, +/- SD]

Average curing time, 2nd attempt to peel off

[h:min:sec post-application, ± SD]

Average curing time, 3rd attempt to peel off


Average curing time, 4th attempt to peel off


5 °C/20 %RH test/dry surface 4:02:19 0:02:27 5 °C/80 %RH test/dry surface 4:00:21 0:00:27 20 °C/20 %RH test/dry surface 4:00:42 0:00:12 20 °C/80 %RH test/dry surface 4:03:46 0:04:32 22:43:51 40 °C/20 %RH test/dry surface 4:02:05 0:02:31 40 °C/80 %RH test/dry surface 4:03:46 0:04:32 20 °C/80 %RH test/wet surface 3:55:36 0:00:19

47

Table B-5. Temperatures prior and post-application of DeconGel® 1108.

Test Temperature [ºC] measured during equilibration/pre-application

Temperature [ºC] measured during curing/post-application

Mean ± SD Range % completeness Mean ± SD Range 5 °C/20% RH test/dry surface 7.3±0.0.13 7.0-7.8 100 7.4±0.0.18 7.1-9.0 5 °C/80% RH test/dry surface 7.2±0.0.10 6.8-7.4 100 7.5±0.0.19 7.2-8.6 20 °C/20% RH test/dry surface 19.1±0.74 18.3-20.0 100 20.0±0.10 19.9-20.5 20 °C/80% RH test/dry surface 19.7±0.10 19.2-20.0 100 19.6±0.50 18.2-20.0 40 °C/20% RH test/dry surface 40.1±0.09 40.0-40.5 100 40.1±0.07 40.0-40.4 40 °C/80% RH test/dry surface 37.7±1.3 30.0-38.1 74 35.0±0.32 33.4-35.3 20 °C/80% RH test/wet surface 22.2±0.10 22.0-22.4 100 21.7±0.17 21.3-22.3

Table B-6. RH conditions prior and post-application of DeconGel® 1108.


Mean ± SD Range % completeness Mean ± SD Range 5 °C/20% RH test/dry surface 19.2±0.30 18.4-20.9 100 41.0±6.00 19.7-63.9 5 °C/80% RH test/dry surface 82.9±0.13 82.5-83.3 100 82.3±0.56 79.2-83.4 20 °C/20% RH test/dry surface 20.1±1.50 4.23-30.7* 84 81.6±6.8 23.1-84.7 20 °C/80% RH test/dry surface 80.1±0.50 76.3-86.9 100 82.4±3.4 79.4-90.4 40 °C/20% RH test/dry surface 20.5±1.00 19.7-24.9 100 60.2±9.3 19.7-71.5 40 °C/80% RH test/dry surface 80.5±1.10 74.6-81.6 99.5 77.1±0.61 74.7-79.1 20 °C/80% RH test/wet surface 79.1±0.02 78.4-79.1 100 87.5±6.1 79.0-94.6

Table B-7. Other parameters for application of DeconGel® 1108.

Test Air flow during equilibration/post-

application [ft3/h/% of target ventilation rate]

Average amount of coating used

for 1st application [mL./coupon]

Average amount of coating used for

2nd application [mL./coupon]

Average application rate [sec per coupon, ± SD]

Final coating thickness [mm]

5 °C/20% RH test/dry surface 9.7 / NA 107 / NA 18.8 12.9 0:01:01 0:00:06 1.1-2.5 5 °C/80% RH test/dry surface 9.0 / NA 99 / NA 10.7 9.1 0:00:53 0:00:02 1.1-2.5 20 °C/20% RH test/dry surface 8.8 / 8.9 97 / 99 12.9 10.9 0:00:55 0:00:05 1.1-2.5 20 °C/80% RH test/dry surface 10.3 / NA 114 / NA 13.4 9.6 0:00:58 0:00:05 1.1-2.5 40 °C/20% RH test/dry surface 14.7 / NA 163 / NA 16.5 16.5 0:01:06 0:00:10 1.1-2.5 40 °C/80% RH test/dry surface 6.4 / NA 72 / NA 17.0 8.1 0:00:54 0:00:05 1.1-2.5 20 °C/80% RH test/wet surface 9.0 / 9.9 100 / 110 13.4 12.2 0:00:54 0:00:12 1.1-1.4


48

Table B-8. Curing time assessments for DeconGel® 1108.









5 °C/20% RH test/dry surface 3:58:50 0:00:45 17:59:51 0:00:14 5 °C/80% RH test/dry surface 3:59:10 0:00:45 18:00:14 0:00:36 20 °C/20% RH test/dry surface 3:59:53 0:00:10 20 °C/80% RH test/dry surface 3:58:44 0:00:46 17:58:51 0:00:56 23:58:49 0:00:38 31:58:04 0:00:27

40 °C/20% RH test/dry surface 4:00:48 0:00:32 40 °C/80% RH test/dry surface 3:57:12 0:00:43 18:00:39 0:02:34 20 °C/80% RH test/wet surface 3:58:14 0:00:51 17:59:11 0:00:17

49

Table B-9. Temperatures prior and post-application of Stripcoat TLC Free™.

Test Temperature [ºC] measured during equilibration/pre-application Temperature [ºC] measured during curing/post-application

Mean ± SD Range % completeness Mean ± SD Range 5 °C/20% RH test/dry surface 5.98±0.25 5.56-6.52 100 6.33±0.10 6.02-6.53 5 °C/80% RH test/dry surface 8.5±0.16 8.24-8.78 0 8.5±0.17 8.3-9.4 20 °C/20% RH test/dry surface 20.0±0.06 20.0-20.7 100 20.0±0.09 19.9-20.5 20 °C/80% RH test/dry surface 21.4±1.2 17.3-27.2 100 20.7±0.20 20.6-21.6 40 °C/20% RH test/dry surface 40.1±0.06 39.9-40.3 100 40.1±0.06 40.0-40.4 40 °C/80% RH test/dry surface 40.0±0.22 25.9-40.0 61 36.8±3.8 25.9-40.0 20 °C/80% RH test/wet surface 21.9±0.09 21.6-22.1 100 21.3±0.10 21.2-21.7

Table B-10. RH conditions prior and post-application of Stripcoat TLC Free™.


Mean ± SD Range % completeness Mean ± SD Range 5 °C/20% RH test/dry surface 23.8±3.0 20.00-30.3 66 37.1±3.0 22.4-44.0 5 °C/80% RH test/dry surface 78.6±1.2 75.7-80.1 100 78.8±0.30 77.4-79.6 20 °C/20% RH test/dry surface 21.7±1.4 20.0-24.1 100 44.0±11.9 20.0-73.4 20 °C/80% RH test/dry surface 78.8±3.5 62.7-92.9 92 80.4±0.30 79.2-82.6 40 °C/20% RH test/dry surface 20.2±0.15 18.9-21.1 100 24.1±5.9 18.46-44.7 40 °C/80% RH test/dry surface 82.3±0.62 71.5-92.0 61 82.1±3.4 82.1-93.8 20 °C/80% RH test/wet surface 80.0±0.017 80.0-80.1 100 87.5±5.5 78.9-94.4

Table B-11. Other parameters for application of Stripcoat TLC Free™.

Test Air flow during equilibration/post-

application [ft3/h/% of target ventilation rate]


1st application [mL./coupon]


2nd application [mL./coupon]

Average application rate [sec per coupon, ± SD]

Final coating thickness [mm]

5 °C/20% RH test/dry surface 9.5 / NA 106 / NA 5.7 5.5 00:29 00:05 <2 5 °C/80% RH test/dry surface 8.7 / NA 97 / NA 5.7 4.8 00:25 00:02 <2 20 °C/20% RH test/dry surface 9.1 / NA 101 / NA 6.4 7.1 00:27 00:03 <2 20 °C/80% RH test/dry surface 9.0 / NA 100 / NA 4.8 3.1 00:25 00:01 <2 40 °C/20% RH test/dry surface 8.8 / NA 98 / NA 5.7 4.3 00:30 00:03 <2 40 °C/80% RH test/dry surface 8.0 / NA 88 / NA 5.7 3.6 00:22 00:03 <2 20 °C/80% RH test/wet surface 9.1 / 9.2 101 / 102 5.7 4.7 00:24 00:03 <2


50

Table B-12. Curing time assessments for Stripcoat TLC Free™.









5 °C/20 %RH test/dry surface 4:00:52 0:00:23 5 °C/80 %RH test/dry surface 4:00:49 0:00:44 20 °C/20 %RH test/dry surface 3:59:34 0:00:29 20 °C/80 %RH test/dry surface 4:00:06 0:00:37 40 °C/20 %RH test/dry surface 4:00:08 0:00:36 40 °C/80 %RH test/dry surface 4:00:48 0:00:37 20 °C/80 %RH test/wet surface 3:58:34 0:00:34

51

Appendix C: RH profiles during curing of decontamination coatings

52

Figure C-1. RH profiles during curing of CC Wet/CC Strip.

53

Figure C-2. RH profiles during curing of DeconGel® DG1108.

0

10

20

30

40

50

60

70

80

90

100

-5 0 5 10 15 20 25 30 35 40

RH [%

]

Time [h]

Decon Gel DG1108 RH Profiles

RH Test 6- 40T, 20RH






RH Test 27 20T, 80RH WET

54

Figure C-3. RH profiles during curing of Stripcoat TLC Free™. The double spikes in RH are

associated with the application of two coatings.

0

10

20

30

40

50

60

70

80

90

100

-2 -1 0 1 2 3 4 5 6 7

RH [%

]

Time [h]

StripCoat RH Profiles

RH Test 1 - 20T, 20RH

RH Test 8- 5T, 20RH





RH Test 25 20T, 80RH WET

Office of Research and Development (8101R) Washington, DC 20460

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evaluation of the curing times of strippable coatings and

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