Seneffe, 6th May 2009 Concerning: Method statement for the on site glazing with the WSG reparation kit

METHOD STATEMENT

This application procedure is a general guide for applying DOW CORNING structural silicone Dow Corning ®

993 with the WSG reparation kit on site.

The same joint dimension recommendations are valid as for the glazing in factory, as communicated

previously by Dow Corning.

1. Clean – Joint surfaces (glass (with an eventual residue of DC structural sealant I initial adhesion was

OK) and metal) must be clean, dry, dust free and frost free. For the cleaning, the R40 cleaner has to

be used, and it has to be applied using the two-cloth cleaning method. Dow Corning recommends

cleaning in two steps; a first cleaning procedure to remove the high amount of dust that is present on

the frames, and another cleaning procedure just before the glass installation. Both procedures have

to be done with the two-cloth cleaning method.

2. Treat the metal substrate as described in the test result letter from Dow Corning

3. Place - The panel to be glazed is set in place according to standard practices.

4. Apply- Sealant is applied by filling the joint cavity completely, being careful to not leave “air pockets”.

Before the application of the sealant can be started, it should be assured that the substrates are NOT humid

(no condensation), and that the temperature is between 5°C and 40°C. If not, the application should not be

started. The application should be done maximum 1hours after primer application.

5. Tool - Tooling techniques are used to strike the sealant and making certain the sealant has the

proper configuration and fully contacts the glass and the metal. 

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6. The glass panels have to be mechanically retained until the joint has completely cured. It is

recommended to keep the units mechanically retained for a minimum of 3 days to make sure that a a

full adhesion is obtained.

During all previous steps, a quality control is required, and this for every day of the installation. The quality

control should contain:

1. Butterfly test (1/half day)

2. Snaptime test (1/half day)

3. Adhesion tests (Peeltest or H-piece); 3 samples / day on representative aluminium substrate

Results of quality control tests, as well as site conditions (temperature, humidity, lotnumbers used, …) should

be written down in the logbook on a daily basis.

This logbook should be kept on site.

The following sections are intended to provide more detailed information in each of these areas:-

Substrate Cleaning and Priming Procedure Dow Corning refers to the Dow Corning structural glazing manual for more detailed information around the

substrate surface treatment.

Setting Procedures Glazing, in general, can have very specific procedural requirements depending on the application. The

following two points offer general rules to follow in weather sealing applications:-

1. Care must be taken to ensure that joint surfaces that have been cleaned, that they are dry are not

contaminated.

2. For site glazing applications, the silicone physically cannot be applied the moment that the substrates

are assembled. In this case the joint preparation must be accomplished again immediately prior to

applying the silicone.

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Sealant Application Procedure It is critical that the sealant fills the entire joint or cavity and firmly contacts all surfaces to which it is intended

to adhere. If the joint is improperly filled, good adhesion will not be achieved and sealant performance will be

impaired. Sealant should be applied as follows, using the WSG reparation kit

1. Remove all red part from the base cartridge

2. Remove the transparent strip at the top of the cartridge

3. Cut the top part of nozzle of the catalyst, the oil which may be present should be left inside and not

poured out

4. Turn the catalyst cartridge upside down into the base cartridge and squeeze the catalyst out (into the

base cartridge) by pushing the end part of the catalyst cartridge. Don’t try to push everything out, it is

normal that some catalyst is let inside of the catalyst cartridge

5. Screw the metallic part (plunger) inside the base cartridge until you see it turning inside.

6. Place the cartridge upside down in the mixer. Attach the plunger by the 2 little screws at the bottom

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7. Place the top part metal and fix it on the machine by turning it

8. Start the machine and let it mix for 3 minutes. You will see the mixing occurring in the cartridge

9. Stop the machine, and remove the mixed cartridge

10. Attach the plastic nozzle, and place the cartridge in the pneumatic gun

11.

12. Ready to use!

13. It is very important that the sealant is applied within 10 minutes after the mixing the cartridge.

14. Apply the sealant in a continuous operation using an application gun or pump. A positive pressure,

adequate to fill the entire joint, should be used. This can be accomplished by either “pushing” or

“pulling” the sealant bead ahead of the application nozzle.

Care must be taken to ensure complete fill of the joint cavity.

This is critical since the effectiveness of the silicone is largely dependent on the sealant bite (contact

area).

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For the vision glasses, the structural sealant will be filled from the outside; while for the spandrel

panels the structural sealant will be filled from the outside.

Dow Corning can provide a training and demonstration on how to use the WSG for the first time on site.

TOOLING TECHNIQUES

It is preferred that the sealant be tooled without the use of tooling aids such as water, soap or solvent,

often called “wet tooling”. Tooling aids can migrate between the sealant and the substrate and

adversely affect adhesion. Additionally, tooling aids may interfere with sealant cure. Most commonly

used and approved tooling aids are wooden sticks, silicone cartridges and polyethylene sheets. Other

aids are approved as well as long as an aesthetically nice joint can be obtained.

IMPORTANT REMARK: It is NOT allowed to first apply the silicone sealant bead and then ‘push’ the

glass onto the sealant, for obvious reasons. The glass needs to be installed prior to the jointfilling with the

structural sealant.

Quality Control More information around quality control procedure, and an example of the logbook, can be found in

our structural glazing manual.

Kind Regards,

Valerie Hayez

Technical Service Engineer

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