Microbiological Process Discussion

Some Auxiliary Effects of Textile Fungicides'C. H. BAYLEY

National Research Coutncil of Canada, Ottawa, Canada

Received for publication September 28, 1955

The circumstances which, during the past 10 years,have led to the increasing use of textile fungicides incombating microbiological attack, chiefly on cotton tex-tiles, have been fully covered in numerous scientific andtechnical papers and reports published during that pe-riod. It is not, therefore, the purpose of this paper todwell on the background of this subject except to note,in passing, that there is now w-idespread interest in thedevelopment, testing and mechanism of action of thevarious chemical substances and treatments which areconsidered to have merit as textile fungicides.

In considering ways and means of imparting to a tex-tile material a particular functional characteristic, suchas resistance to microbiological attack as obtained bya particular fungicidal treatment, it is natural and pos-sibly, inevitable, that some of the auxiliary effects aris-ing from the treatment will be overlooked and thispaper discusses some of these effects.

Because textile fungicides are applied to fabrics whichwill be used outdoors, it is of interest to consider thepart that these fungicides play, with respect to the over-all deterioration which fabrics, used in this way, canundergo.The two main deteriorating agencies concerned are

sunlight and microbiological attack. There are others,such as the effect of elevated temperatures and of re-peated wvetting and drying, but until we have a clearerpicture of the interplay of effects which go to make upthe complicated process kinowsn as "+weathering," it isonly possible to give a partial assessment of the suita-bility, or otherwise, of a given fungicidal treatment.

Since 1945, the Textile Research Section of the Na-tional Research Council of Canada has carried out workin the field of the microbiological deterioration of textilematerial for the Canadian Armed Services and thispaper presents a discussion of some of the auxiliaryeffects of textile fungicides chiefly with respect to theirability to suppress or enhance chemical damage duringweathering.

I Paper read at meeting of the Societv of Industrial MNIicro-biology, Michigan State College, East Lansing, Michigan,September 7, 1955.

The Photochemical Degradation of CelluloseMuch of the earlier work in this field has had as its

object the investigation of the chemical damage whichresults when cotton, dyed with certain dyes, is exposedto sunlight (Scholefield and Patel, 1928). This phe-nomenon seemed to be characteristic of certain orange,yellow and red vat dyes, and it was first believed thatthe energy of only the short-wave radiation, that is, inthe blue and ultraviolet region of the electromagneticspectrum, was concerned in the effect (Landolt, 1933).Subsequent work has shown that radiation in the visi-ble part of the spectrum can also cause tendering and itis now recognized that radiation of any wavelength cancause degradation of cellulose and other fibers providedit is absorbed, in sufficient amount, by the fiber anid theenergy content is sufficiently high.

The portion of the spectrum involving solar radiationis from 1500 A in the ultraviolet region through thelonger wavelengths comprising the visible spectrum(4000 to 8000 A) anid extending beyonid this, into theinfrared, up to 40,000 A.

Most investigatioins have been concernied with theultraviolet region (1500 to 4000 A), in as much as thehigher energy contenit of this region suggested thatphotochemical reactions would occur more readily here.Much of the published data is contradictory, doubtlessdue to such factors as the experimental difficulty of re-stricting the radiation used to reasonably narrow re-gions of the spectrum, the variable nature of some of thelight sources used, and to solarization effects on lightfilters.

Other complicating factors have beeni the effects ofwater vapor and of oxygen. It was previously consideredthat the presence of oxygen was niecessary to obtainbreakdown of cellulose exposed to light, this belief re-lating to the observation that the breakdown productsof cellulose produced in this way have the propertiesof the so-called reduciing type of oxycellulose. However,it has been shown by Heuser and Chamberlain (1946)that this is not the case and the more recent work ofEgerton (1949) has done much to resolve some of thedifficulties of this complex matter.

Egerton's work gives a reasonably satisfactory basisfor the current belief that the breakdowni of cellulose

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caused by light operates through two more or less dis-tinct mechanisms, depending upon the particular re-

gion of the electromagnetic spectrum in which the ex-

posure is made. In the far (short-wave) ultraviolet region,for example, 2535 A, the effect is one of photolysisinvolving absorption of energy by the cellulose with ulti-mate rupture of the carbon-to-carbon and carbon-to-oxygen bonds, a process which, in itself, does not re-

quire the presence of oxygen, although some of thedegradation products may be capable of undergoing,oxidative degradation subsequently. In the near ultra-violet region, for example, around 3400 A, and in thevisible regioin of the spectrum, the above process can

also occur, but at a reduced levTel owing to the lower-amounts of energy received by the cellulose.

It has been shown that the degradation produced bythe presence of certain vat dyes does not occur in thefar ultraviolet region but does occur in the near ultra-violet region. According to Egerton's theory, this proc-

ess is one of photosensitization involving the productionof active oxygen and/or hydrogen peroxide to whichthe former gives rise in the presence of water vapor

and which leads to the oxidative degradation of the cellu-lose.

It will therefore be obvious that, insofar as degrada-tion resulting from exposure to sunlight is concerned,one or both of these mechanisms may operate, sinceradiation in both the near and far ultraviolet regions ispresenit.

Other T'extile Treatments with which Fungicidesare A ssociatcd

Because most textile materials with which fungicidesare used are designed for use outdoors, it is not surpris-ing that. most of them are required to have some meas-

ure of resistance to water penetration. This is usuallyachieved by treatment wvith some hydrophobic com-

pound such as a wax. Additional treatments, for exam-

ple, for flame resistance or for control of color are some-

times required and in somne instances, the totaltreatment to which the fabric is subjected comprises a

fairly complex mixture in which the fungicide is onlyone component.

Table 1 gives a list of some of the commoner textileitems to which it is advantageous to apply a fungicide.It also shows the extent to which properties otherthan mildew resistance are required together with an

approximate assessment of the severity of exposure tosunilight to be expected. In all cases it would be ex-

pected that exposure to Nater, chiefly as rain, will bemoderate to high.

It will be noted that in most cases the probable ex-

tent of exposure to sunlight is high; also, that, for manyof the more important items, it is possible that water-resistant and flame-resistant finishes will be present.From the viewpoint of practical application it may

TABLE 1. Classification of textile items (cotton orother cellulosic fiber) used outdoors and requiring

the use of a textile fungicide

Probable Extentof Exposure to

SunlightItem Possible AdditionalItem ~~~~Requirements

0 0

Paulins.x... x

I ~~~~~~~~xMotor vehicle-covers ... *(WR), (WR + P),

(WR + FR), orTentage ... (WR + FR + P) xWebbings ........xSandbags xAwnings xFabrics for outdoor fur- (Wit) or (WR + P)

niture ........... xShade cloths for plants. xFire hose ............... x xCordage ....... (WR) x xFishing gear ........... x x x

* WR = water-resistant treatment; FR = flame-resistanttreatment; P -- colored pigment

therefore be said that fungicides will be used as the soletreatment on a limited range of fabrics, for example,shade cloths and fire hose, but that in the great major-ity of cases they wAill be used in conjunction with water-resistant treatments or with both water- and flame-resistant treatments, with or without the addition ofcolored pigments.

It is therefore of interest to study the behavior, onweathering, of textile fungicides under the followingconditions: In the absence of any other finish;2 in thepresence of water-resistant treatments; in the presenceof water-resistant treatments plus pigment and filler;and in the presence of water-resistant treatments, pig-ment, filler plus flame-resistant treatments.The following section gives the results obtained with

a niumber of fungicides examined with respect to all ofthe above conditions except the presence of flameproof-ing treatmnents. The results of work done elsewhere onflameproofed material have shown that the results arenot substantially different provided the ingredients usedto impart flame resistance do not in themselvres contrib-ute to the deterioration of the fabric.

DATA ON WEATHERING CHARACTERISTICS OF

TEXTILE FUNGICIDES

The methods used in applying the treatments tofabric and the description of the fungicides used havealready been published (Bayley and Weatherburn,

2 The term "finish" is used in the textile sense throughoutthis paper. It refers to the practice of applying chemicals orchemical treatments to the textile material in order to impartcertain functional characteristics, for example, water re-sistance, mildew resistance, flame resistance, and so forth.

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TABLE 2. Weathering behavior of mineral dye and cuprammonium treatments

Content of Compound

Fe2sO CuO

Breaking StrengthLoss

Buried 2 Weatheredweeks 4 months

Increase inCupram-moniumFluidity

Loss of Compound

Cr2sO Fe2O3 CuO

Ref.

% % % % % rhes % % %Untreafed control 98 42 13.5 (Bayley and Weather-

burn, 1947)Chromic oxide alone 0.98 100 26 7.1 2 -Ferric oxide alone 1.23 100 28 12.2 - 0Chromic oxide + ferric 1.28 0.70 88 9 4.2 0 0 - (Bayley and Weather-oxide (mineral dye) burn, 1947)

1.00 0.80 - 100 17 5.0 7 17.5 - (Bayley and Weather-burn, 1948)

0.63 0.94 93 18 5.6 - (Bayley and Rose, 1954)Cuprammonium _ 1.41 0 39 12.7 - 49 (Bayley and Weather-

burn, 1947)

TABLE 3. Weathering behavior of mixtures of inorganicchromium and copper*

Content of Breaking CCompound Molar Strength Loss ._CopudMolar ______

a.

Treatment RiCu 0.*Cr2O3s

9o

u

0...0

L~~~~~ U~;L

% % % % rhes %Untreated control - - - 100 51 14.2 -

Chromic oxide plus 0.160.20 0.42 95 25 8.0 66copper carbonate 0.760.11 3.60 97 16 6.3 51(low-copper) 1.16 0.09 6.74 96 16 7.2 26

Chromic oxide plus 0.14 0.66 0.11 7 31 10.1 82copper carbonate 0.86 0.60 0.65 47 13 5.7 49(medium-copper) 1.29 0.61 1.10 68 10 5.4 31

Chromic oxide plus 0.10 1.30 0.04 37 2 12.2 86copper carbonate 0.78 1.16 0.35 11 9 5.9 53(high-copper) 1.45 1.21 0.63 11 13 5.2 36

* Literature reference (Bayley and Rose, 1954).

1945, 1947, 1948; Bayley and Rose, 1954). The refer-ences cited also give details of the method used forexposing the samples to weathering and for evaluatingthe physical, chemical and fungicidal properties of thetreated fabrics before and after weathering and formeasuring the extent of deterioration caused by weath-ering.

Behavior of Fungicides IVhen Used Alone

Inorganic treatments. The practice of treating cottonduck to be used in the manufacture of tentage withmixtures of chromic and ferric oxides for impartingresistance to microbiological attack is one of long stand-ing. Fabric treated in this way is known as "mineralkhaki" and the process termed "mineral dyeing." It hasbeen widely used in Britain. The other long-used inor-ganic treatment is the cuprammonium process in whichthe cotton fabric is passed through a dilute solution of

cuprammonium hydroxide which produces a partialgelatinization of the fabric surface and the retention ofsome of the copper by the fabric.

Table 2 shows some of the data obtained with thesetreatments. It will be seen that the mineral khaki treat-ment gives considerable protection against actinicbreakdown, but is not very effective in preventing mi-crobiological deterioration under the conditions of se-

vere contamination such as may occur with tentage.The treatment shows a high degree of permanence dur-ing weathering.The cuprammonium treatment shows a considerably

greater fungicidal efficacy but relatively poor perma-

nence. The fluidity data show that it affords less pro-

tection against actinic breakdown.For the above two inorganic treatments, therefore,

it will be seen that the first provides good protectionagainst actinic breakdown but poor resistance to severe

microbiological attack. The second provides good ini-tial fungicidal properties but, on weathering it loses itscopper fairly rapidly, thus decreasing the resistance ofthe treated fabric to microbiological attack. Moreover,the treatment does not provide any marked protectionagainst actinic breakdown.

Obviously, it would be desirable to find an inorganictreatment which would provide protection against ac-

tinic breakdown and a high level of resistance to micro-biological attack both initially and after weathering.Such a treatment seems to be provided by using a

mixture of chromic oxide and copper carbonate anddata taken from this work are shown in table 3. Theeffectiveness of such treatment was suggested in workpublished in 1948 (Bayley and Weatherburn, 1948) andconfirmed more recently (Bayley and Rose, 1954).The treatments shown fall into three categories of

low, medium and high contents of copper respectively.It will be noted that, in all cases, the loss in breakingstrength produced by weathering is very much lowerthan that of the untreated control, and these losses

Treatment

Cr203

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0 1 2 3 4 5 6 7

MOLAR RATIOc%O

FIG. 1. Effect of the ratio of Cr203 to CuO on the breakingstrength loss of unbleached cotton duck exposed to weathering.

are, in certain cases, lower than those obtained in themineral dye treatments (table 2). In addition, theresistance to soil burial is satisfactory in the two high-copper samples containing 0.78 and 1.45 per cent copperas oxide. The losses of copper on weathering, in thesamples containing 1.29 and 1.45 per cent copper as

oxide were 31 and 36 per cent respectively, which isconsiderably lower than the 49 per cent loss of coppershown by the cuprammonium-treated sample referredto above (table 2).The above data may be plotted on the basis of

breaking strength vs. molar ratio Cr2O3: CuO, the threecurves representing the low-, medium- and high-copperlevels. These are shown in figure 1 in which it is ob-served that the points of inflexion for the curves forlow- and medium-copper appear to occur around a

molar ratio of unity. In order to check this point more

carefully, a further series of treatments was preparedand subjected to weathering tests during the summer

of 1954. The data obtained show the points of inflexionto be at the molar ratio of Cr2O3:CuO = 1.

Reference should be made to two other recentlydescribed inorganic treatments containing chromiumwhich appear to show promise; namely, lead chromate(Dean et al., 1946) and copper chromate (Block, 1949).Organic treatments. Of the organic fungicides which

have been used on textiles, the most important are

certain organo-metallic compounds of copper and zincand the compound 2, 2'-dihydroxy-5, 5'-dichloro di-phenylmethane.

Of the copper compounds, copper naphthenate hasbeen used for many years and this compound togetherwith zinc naphthenate and salicylanilide were the onlycommercial compounds which had been evaluated as

textile fungicides prior to World War II. As the resultof war needs, copper naphthenate, because of its com-

paratively high fungicidal potency and despite itsobjectionable odor, was put into wide use as a textilefungicide. Two auxiliary effects which it shows are of

TABLE 4Effect of content of copper naphthenate on the breaking strength

produced on weatheringContent of Copper Breaking Strength Loss

Untreated control 510.08 360.23 400.33 480.66 62

Fabric-unbleached cotton duck; time of weathering-5months.

interest. These are the extent to which it enhancesactinic breakdown of cotton and the effect of waterleaching on its fungicidal efficacy.There has been considerable argument regarding

the enhancement of actinic breakdown of cotton, andit may be of. interest to give some of the data whichhave been obtained in numerous investigations in thislaboratory. The data given in table 4 are typical of themass of data obtained. They illustrate the repeatedobservations that the presence of copper naphthenatein amounts corresponding to 0.3 per cent copper or

less does not result in breaking strength losses greaterthan that shown by the untreated control but, rather,exert some protective action. This effect has beennoted with all organic copper compounds so far tested,with the exception of the oleate, linoleate and tallate.The use of these latter compounds has resulted inbreaking strength losses greater than those of the un-

treated controls, but this is believed to be due to theinduced oxidation of the cellulose resulting from theprogressive oxidation of the unsaturated portions ofthese compounds. Where the organic portion of themolecule contains no unsaturation, as in copper naph-thenate and copper 8-hydroxyquinolinolate, this effectis not noted.A property of copper naphthenate which is related

to its fungicidal efficacy is its tendency to undergopartial hydrolysis with marked reduction of fungicidalefficiency. This effect was first noted in this laboratoryin 1944 when it was found that samples of cottonosnaburg, used in the manufacture of sandbags andtreated with a mixture of copper naphthenate andcreosote, showed a greater tendency to undergo micro-biological attack in a 2-week soil burial test if subjectedto a 24-hour leaching treatment prior to the soil burialtest.The data shown in table 5 illustrate the effect which

seems to be a general one, related to the loss of naph-thenic acid on the partial hydrolysis of the compound.Since the naphthenate portion of the copper naphthe-nate molecule exerts considerable fungicidal action,the loss, through hydrolysis on leaching, of a portionof it would be expected to lead to an overall reduction

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TABLE 5

Effect of prior leaching on resistance to soil burial (cotton fabricstreated with copper naphthenate)

Breaking Strength Loss due to

Approximate Soil BurialFabric Initial Content

of Copper Sample un- Sample leachedleachedlepriorleached prior prior to burial

No. 8 unbieached cot- 0.3 0 44.2ton duck 0.8 0 19.5

Cotton osnaburg 0.3 0 61.80.8 0 22.8

TABLE 6Effect of leaching on solvent-solubility of copper naphthenate

on cotton fabrics

Before Leaching After Leaching

Total Total Increase

copper in- copper in-soluble solubleform form

% % %o % %No. 8 unbleached cotton 0.31 23.2 0.28 46.4 23.2dUck 0.76 4.7 0.70 18.6 13.9

Cottoni osnaburg 0.29 19.7 0.23 49.1 29.40.72 22.2 0.71 46.5 24.3

Cotton sheeting 0.28 23.6 0.26 46.2 22.6

of fungicidal efficacy. Copper naphthenate, as produced,is soluble in petroleum solvent but when it undergoespartial hydrolysis, the reaction product, which is prob-ably a basic form of the compound, is insoluble insolvent. Hence by measuring the amount of solvent-insoluble copper on the fabric before and after leaching,it is possible to estimate the extent of hydrolysis whichhas occurred. This is shoNvn in table 6 where it is alsoseen that there is some evidence of hydrolysis in thecompound as first applied, that is, before leaching.This must be attributed to the fact that moisture inthe air and the regain moisture present in the fabriccan give rise to hydrolysis. Support of this view isfurnished by the fact that the hydrolysis effect is verymuch reduced if the naphthenate is applied in con-junction with wvax.

Copper 8-hydroxyquinolinolate. While the fungicidalproperties of this compound have long been known, itis only in the last few years that it has been widelyapplied in the textile field (Benignius, 1948). It can beapplied in the form of a water or solvent emulsion or,less conveniently, by a 2-bath process in which thefabric or yarn is treated successively with an aceticacid solution of 8-hydroxyquinoline, squeezed to re-move excess of the solution and then passed into asolution of a copper salt, for example, the acetate. A

TABLE 7Fungicidal and weathering properties of copper

8-hydroxyquinolinolate

Breaking Strength In-Loss crease

___________of Cu-

v Method of . - pram-Compound = Application c > - monium

o of Compound c -nni 3 Fluidity~~ ~ ~~O on

0.~~~~~u 0 o Weath-o0 ering

%to o% % % rhes

Untreated control - 100 100 54 16.3

Copper-8 0.03 Aqueous dis- 0 10 39 15.90.09 persion, 1- 0 0 33 12.70.12 bath 0 0 33 11.70.19 0 0 29 11.5

Copper-8 "solu- 0.04 Solvent solu- 0 0 26 12.3bilized" 0.09 tion, 1-bath 0 0 27 12.8

0.13 0 0 33 12.10.19 0 0 31 10.9

Copper naphthe. 0.57 Solvent solu- 31 69 34 15.9nate 1.02 tion, 1-bath 26 67 36 16.0

1.54 0 52 42 18.6

reversal of the order of these two baths has been foundto give greater control of the pick-up of copper by thefabric. More recently, preparations of the compound insolubilized form (U. S. Patents 2,561,379 and 2,561,-380) have become available. In this form it is solublein cheap solvents, for example, Stoddard solvenit, andcan be conveniently applied from these and fromaqueous emulsions of solvent containing the compound.The comparatively high fungicidal potency of the

compound in comparison with copper naphthenate isshown in table 7. Of equal interest is the fact that itseems to provide considerable protection from actinicdegradation.

Permanence to Veathering of Organic Fungicides lVhenEUsed Alone

The one shortcoming of the organic fungicides whenused alon-e is their relatively poor permanence toweathering. Without exception, they are removed fromthe fabric fairly quickly. This rapid removal can belargely overcome by the application of the fungicide inconjunction with a protective agent such as a wax.This is discussed in the next section.

Effect of Fiber ConstituentsIn fungicidal treatments involving the application

of metallic compounds in inorganic or organic form, itis of interest to consider the possibility of auxiliaryeffects which relate to the fact that the fibers to whichthe compounds are being applied do not consist of purecellulose. The cotton fiber contains around 95 per centcellulose xvhich is a higher proportion than in any ofthe others concerned. This is an over-all percentage,

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however, and it should be noted that the content ofcellulose in the primary wall of the fiber has been shown(Tripp et al., 1951) to be around 55 per cent, thebalance being made up of protein (14 per cent), pec-tic substances (9 per cent), wax (8 per cent) andminor amounts of other substances, for example, ashand cutin.

In fibers such as flax and jute, the amounts of thesenoncellulosic materials are still greater, and it is knownthat many of them have the power of combining withmetal ions, this being the case with pectins (Heuser,1947) and proteins. Cellulose itself has some power tocombine with cations, by virtue of carboxylic groups inthe cellulose chains. The extent to which such groupsare present will depend on the chemical history of thecellulose concerned, but, in general, it may be con-cluded that the chief mechanism through which cellu-losic fibers combine with cations is through the mediumof their noncellulosic constituents.

In the textile processing of fibers such as cotton andlinen, the amounts of these noncellulosic constituentsare sometimes drastically reduced. In fully bleachedcotton, for example, their amount has been reduced toless than 1 per cent and a somewhat smaller reductionmay also occur where unbleached cotton is subjectedto wet processing at elevated temperatures, as indyeing.To date, little or no attention has been given to this

effect, although it obviously has an important bearingon the decision as to whether or not it is advisable tocarry out any type of pretreatment, such as scouring,dyeing, bleaching, and so forth, on a fabric to which ametallic-type fungicide is to be subsequently applied,it being obvious that any such pretreatment shouldbe no more drastic than is necessary.Some earlier work carried out in this laboratory

(Rose and Bayley, 1954) and dealing with the prolongedleaching of flax forestry fire hose treated with coppernaphthenate and copper 8-hydroxyquinolinolate hadgiven some indication that noncellulosic material pres-ent in the fiber resulted in an increased retention ofmetal with consequent fungicidal protection of thefabric. The data are shown in table 8. The conditionsof leaching used in these experiments were severe, eachsample being exposed to a flow of 10 liters per hour ofwater at 25 i 1.0 C continuously for 60 days. Underthe circumstances the loss of copper is quite moderateand is very much less than would be expected from acotton fabric. There is little doubt that this effect isrelated to the greater capacity of unscoured flax tobind metal ions.

In further work on this problem a study was madeof the retention, during weathering and during leach-ing, of copper naphthenate (CuN), copper-8 (Cu8) andcopper carbonate (CuO) applied to unscoured or partlyscoured and scoured cotton, flax and jute fabrics. The

TABLE 8Retention of copper fungicides by unscoured flax fabric under

conditions of severe water leaching

Content of Copper Loss in BreakingLoss of Strength of

Compound After Copper Sample Subjectedniilleaching on to 2 weeks' SoilInitial efor 60 Leaching Burial Test after

days Leaching

%f % %Copper naphthenate 0.42 0.375 11.8 0

1.04 0.985 5.3 01.40 1.215 13.2 0

Copper-8 0.036 0.027 25.0 00.082 0.066 19.5 00.185 0.143 22.7 0

TABLE 9Effect of scouring on the retention of copper fungicides from

cotton, flax and jute fabrics

IntialPer Cent Loss of Copper

Fiber Condition of Compound ofFiber CompoundCmon(As Wet

Copper) Weeatdh- Leached

Cotton Unbleached CuN 0.57 95 5Cu8 0.12 75 23CuO 0.76 91 3

Cotton Scoured CuN 0.57 96 2Cu8 0.12 94 25CuO 0.71 98 1

Cotton Scoured and CuN 0.58 98 24bleached Cu8 0.12 100 38

CuO 0.45 100 7

Flax Unscoured CuN 0.18 14 9Cu8 0.03 27 33CuO 0.25 35 16

Flax Partially CuN 0.26 30 23scoured Cu8 0.035 40 34

CuO 0.72 43 40

Jute Unscoured CuN 0.61 83 10Cu8 0.07 46 27CuO 1.21 53 0

Jute Partially CuN 0.91 55 29scoured Cu8 0.11 76 57

CuO 1.99 79 5

data are given in table 9 and show a well defined trendtowards a greater -holding of metal by the unscouredfabrics.

Behavior of Fungicides in the Presence of Water-ResistantTreatments

Fungicides are often applied in conjunction with waxfinishes on textile fabrics to be used outdoors, in order

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to impart water resistance and also that the wax mayact as a binder for the fungicide and thus greatlyimprove its permanence to removal by weathering.The waxes used for this purpose are mostly of thepetroleum type and while the form in which they areused varies, two main types of application may berecognized.

In the first of these, the wax is present as a coatingon the fibers on which it is deposited from a solventsolution of the wax or by the use of an aqueous dis-persion of the wax in a solution of aluminium acetateor formate. Here, the fungicide may be applied alongwith the wax in solvent-soluble or water-dispersibleform. Such treatments are designed to give a fabricwhich retains a substantial part of its permeability toair, the degree of water resistance achieved being de-pendent largely on the fabric construction, whichgoverns the size of the pores in it.

In the second type of wax treatment, a heavierdeposit of the wax is applied, usually in a wax-in-solventapplication together with such fillers and pigments asmay be required. The net result is a coating whichcovers the fibers and also fills the fabric pores to give asubstantially water-impermeable finish having, also,a low degree of air permeability. In this type of treat-ment a solvent-soluble fungicide is incorporated inthe treatment mixture and where the treated fabric isrequired to be flame resistant, such substances as anti-mony oxide, chlorinated hydrocarbons or resins andtheir adjuncts are also included.

Considering the effect of outdoor weathering oncotton fabrics treated by the above two methods, itwill be apparent that, in regard to the extent to whichthe fiber is exposed to actinic damage, two broad cate-gories of damage may be foreseen. In the first, thefiber is protected by a comparatively thin layer of waxcontaining the fungicide; in the second, the actinicscreening effects of the pigments, fillers, and so forth,may be considerable. That this latter protective effectdoes operate is now well established and in the absenceof damage resulting from chemical tendering of thefibers, or embrittlement of the coating, resulting froman unwise choice of fillers or flame-retardant ehemicals,the heavy, so-called plug-up treatment confers a highdegree of protection to the underlying fibers.The data in this section will therefore be confined to

the first-mentioned type of treatment involving appli-cation of the wax from a solvent solution, since this iswidely used in Canada, for example, on tentage, awn-ings, webbings, and so forth. The primary object ofthe treatment is to impart resistance to water and tomicrobiological attack, and in view of the practicalimportance of waxing treatments, it has been cus-tomary to include in our studies on the weatheringbehavior of textile fungicides an examination of cottonfabrics treated with mixtures of fungicide plus wax.

The waxes normally used in commercial practiceconsist of petroleum waxes of varying physical char-acteristics or mixtures of these. In order to reduce thebrittleness of the coating, especially where the treatedfabrics will be subjected to low temperatures, it iscustomary to include some' low-melting or soft pe-troleum wax of the type usually known as petrolatum.The wax mixture used in this laboratory consists of amixture of cake paraffin wax (parawax) and petrolatumNo. 2, in the proportion by weight of 75:25. This isapplied to the fabric, from solvent, to give a contenton the fabric of approximately 10 per cent.The studies carried out on the weathering character-

istics of various textile fungicides have repeatedlyshown that where the above mixture of waxes is usedunder conditions which exclude any appreciable degreeof light screening, the losses in breaking strength of thewaxed samples were found to be substantially greaterthan those of the unwaxed sample. This effect is alsonoted on samples containing no fungicide, with andwithout wax.

In certain cases, this effect is accompanied by anincrease in cuprammonium fluidity, but, in general, ithas not been possible to show that the effect is relatedto increased chemical degradation of the cotton in thepresence of wax except in the case of scoured or bleachedfabrics which show a moderate increase in fluidity- ofthe scoured samples and a substantial increase in thebleached samples when weathered in the presence ofwax, as compared with unwaxed samples similarlyexposed. Similar results with fully bleached fabric havebeen obtained with and without wax, in acceleratedweathering exposures carried out in the Fadeometer.

It may be thought that the reason for the increasedbreaking strength losses noted in the presence of waxmay be due to physical causes such as interfiber lubri-cation. The application of wax does not cause anysignificant loss in breaking strength in the samplesbefore weathering. This, together with the indicationsof chemical damage in the case of the scoured andfully bleached samples, referred to above, suggeststhat the noncellulosic constituents of the cotton maybe involved in this effect, which is being further ex-amined. Typical data illustrating the effect are givenin table 10. It will be noted that the presence of copper-8tends to reduce markedly the severity of the effect, thereduction being less marked with copper naphthenate.This is in line with the observation, previously referredto, that copper-8 exerts a protective effect in weathering(see table 7).In connection with this effect it has been found that

it is the soft petroleum wax constituent of the waxingmixture that gives rise to the enhanced breakingstrength loss. This is clearly shown both from outdoorweathering data and also from data obtained in Fad-eometer exposures (see table 11).

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TABLE 10. Increase in breaking strength loss caused by waterproofing waxes in presence of fungicide

Approximnate Lo Loss in Breaking Strength on Increase in CuprammoniumoIntent of Losi raigSrnt~ u oWeathering Fluidity on WeatheringFabric Fungicide Waxing, of Original Unweathered(Copper) Sample Unwaxed Waxed Unwaxed Waxed

% % % % rhes rhes

Unbleached cotton duck None No significant loss 51 68 16.2 16.7Bleached cotton duck None No significant loss 40 70 16.4 27.5Unbleached cotton duck plus 0.05 No significant loss 37 61 13.3 13.3

copper-8 0.1 No significant loss 38 54 12.1 13.00.2 No significant loss 38 45 11.6 9.1

Unbleached cotton duck plus 0.1 No significant loss 36 57 10.1 11.9CuN 0.2 No significant loss 40 56 13.1 11.9

0.5 No significant loss 44 59 13.7 13.8

TABLE 11. Effect of "soft" petroleum wax on breakingstrength loss

Loss in Increase inType Content Breaking Cupram-

Fabric of of Strength moniumWax Wax on Fluidity on

Weathering Weathering

Weathering outdoors

% No rhes

Scoured cotton None 25 13.6duck Hard 10.9 25 10.3

Soft 4.4 49 15.8Hard 8.27 10.9 52 16.3Soft 2.7)

Exposure to light in fadeometer

Bleached cotton None _ 45 18.6nainsook Hard 10 44 18.5

Hard 8.27 10.9 63 27.7Soft 2.7)

TABLE 12. Protective effect of wax-filler pigment treatmenton cotton duck treated with copper naphthenate

Content of BreakingTreatment Copper Strength Loss

on Weathering

None.- 37Fungicide (CuN) plus wax pluspigment plus filler ............. 0.37 18.4

Behavior of Fungicides in the Presence of Water-ResistantTreatments of the Wax-Pigment-Filler Type

Treatments of this kind are widely used on suchitems as tarpaulins and motor vehicle covers. The wordfiller refers to the practice of incorporating inert in-organic materials such as talc or clay, in finely dividedform, to increase the capacity of the treatment to sealor plug-up the fiber and yarn interstices in the fabric.Work carried out (Bayley and Weatherburn, 1946)

on the weathering characteristics of cotton duck treatedas above has shown that the screening effect of thepigment plus filler constituents is very marked, theeffect of the wax in causing enhanced breaking strength

losses being no longer apparent. Typical data are givenin table 12.

SUMMARY

In this discussion of some auxiliary effects of textilefungicides it has been shown that where the fungicideis used alone, good protection from actinic breakdown,from microbiological breakdown, and good retentionof the fungicide by the fabric on weathering can beobtained with mixtures of chromium and copper ininorganic form.The organo-metallic fungicides, in common with all

organic fungicides so far examined show relativelypoor resistance to loss on weathering, unless protectedby a binder, such as a wax. Of the copper-organicfungicides, copper napnthenate does not appear tocause enhanced ureakdown of the fabric at low concen-trations bu., suffers from the disadvantage of undergoinghydrol~ysis, with some loss of fungicidal efficacy. Copper8-1hydroxyquinolinolate is an extremely potent fungi-cide and exerts marked protection against actinicbreakdown.The content of noncellulosic material in the fiber to

which copper fungicides are applied influences the easeof removal of the copper in leaching or weathering,and this is attributed to the metal-binding capacity ofcertain of these noncellulosic materials, for example,pectins.The use of soft petroleum wax leads to enhanced

breaking strength losses on weathering and this effectseems to be related to the presence of noncellulosicmaterial on the fiber. The effect is not noted in thepresence of pigments, presumably due to their screeningpower.

REFERENCES

BAYLEY, C. H., AND RoSE, G. R. F. 1954 Textile ResearchJ., 24, 792-802.

BAYLEY, C. H., AND WEATHERBURN, M. W. 1945 Am.Dyestuff Repr., 34, 247-253.

BAYLEY, C. H., AND WEATHERBURN, M. W. 1946 Can. J.Research, F. 24, 193-202.

BAYLEY, C. H., AND WEATHERBURN, M. W. 1947 Can. J.Research, F. 25, 92-109.

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P. H. LOWINGS

BAYLEY, C. H., AND WEATHERBURN, WI. W. 1948 Can. J.Research, F. 26, 24-35.

BENIGNUS, P. G. 1948 Ind. Eng. Chem., 40, 1426-1429.BLOCK, S. S. 1949 Ind. Eng. Chem., 41, 1783-1789.DEAN, J. D., STRICKLAND, W. B., AND BERARD, W. N. 1946

Am. Dyestuff Repr., 35, 346-348.EGERTON, G. S. 1949 J. Soc. Dyers Colourists, 65, 764-780.HEUSER, E. 1947 The Chemistry of Cellutlose, p. 107. 3rd

printing. John Wiley & Sons, Inc., New York.

HEUSER, E., AND CHAMBERLAIN, G. N. 1946 J. Am. Chem.Soc., 68, 79-83.

LANDOLT, A. 1933 Melliand Textilber., 14, 32-36.RoSE, G. R. F., AND BAYLEY, C. H. 1954 Textile Research

J., 24, 229-234.SCHOLEFIELD, F., AND PATEL, C. K. 1928 J. Soc. Dyers

Colourists, 44, 268-274.TRIPP, V. M., MOORE, A. T., AND ROLLINS, WI. L. 1951

Textile Research J., 21, 886-894.U. S. Patents 2,561,379 and 2,561,380.

The Fungal Contamination of Kentish Strawberry Fruits in 1955P. H. LOWINGS1

Ditton Laboratory, Department of Scientific and Industrial Research, Food Investigation, Larkfield, Maidstone, Kent, England

Received for publication October 17, 1955

Fungal rotting of strawberries during transport andmarketing is a maj or factor limiting the area fromwhich manufacturers of jams and preserves can drawsupplies of fruit. Furthermore, the presence of moldmycelium in or on the fruit is of special importance tomanufacturers in the United Kingdom who export tocertain overseas markets, notably the U. S. A., wherethe acceptability of their products may be partiallygoverned by the mold content. This is generally de-terminied by the Howard mold count technique (OfficialMethods of Analysis of the Association of Official Agri-cultural Chemists, 1950), which has been generallyaccepted as providing an index of the extent to whichfruit used for manufacture has beeni subject to deteriora-tioIn caused by fungi. Howard (1917) correlated moldcounts with the extenit of rotting in tomatoes, that is,decompositioin associated with the activities of livingmicroorganisms. Needham and Fellers (1925) extendedthe use of the Howard technique to soft fruit productsbut used the term "moldy berries" apparently as asynonym for fruit rotted by fungi. The word mold is apopular term with no exact definition, but is oftentaken to describe "a microfungus having a well markedmycelium or spore mass, especially an economicallyimportant saprophyte" (Ainsworth and Bisby, 1950).It appears possible, therefore, that the emphasis placedon the unidesirability of the presence of fungal hyphaeas indicating rotting may have become placed on theundesirability of hyphae as such.Beneke et al. (1954) investigated the relation of the

fungus flora to pectolytic breakdown in Michiganstrawberry fruits, and concluded that the amount of

1 This work was carried out during the tenure of a TreasurySenior Research Fellowship as part of the program of theFood Investigation Organization of the Department of Scien-tific and Industrial Research. (Crown copyright reserved).

mold determined by the mold count may not neces-sarily be related to the extent of breakdown in a foodproduct. It may be suggested that a high mold countmay indicate poor handling conditions in so far as suchconditions may favor the development of otherwiseharmless superficial fungi, but it is also possible that amold count may be increased by contamination of thefruit in the field by fungi such as the powdery mildewswhich may not cause rotting and may often beconsidered not to affect quality. Furthermore, themold count gives no indication of the type of softeningand breakdown which sometimes occurs in strawberriesheld in solutions of sulphur dioxide, because althoughenzymes liberated by microorganisms at an earlierstage may be responsible (Pandhi, 1953), the extentof breakdown in susceptible fruits is partially dependenton the length of time that they are held in the preserva-tive solution.The present investigation was undertaken to de-

termine the organisms responsible for the rotting ofstrawberries harvested in mid-Kent during 1955, to-gether with the significance, relative to the Howardmold count, of the mycelium of fungi not associatedwith rotting.

It would normally be preferable that the control ofmold growth on strawberries during transit or storageshould be carried out by modifying environmentalconditions such as temperature. In practice, however,it may not always be possible to obtain adequate controlby such means, and a search was made for a suitablemethod of chemical control. The application of chemi-cals to foodstuffs is strictly limited in the U. S. A. bythe Food and Drug Acts, and in the United Kingdomby the Public Health (Preservatives in Food) Regula-tions, and the problem was therefore approached by

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COEXISTENCE OF PATHOGENS AND PSEUDOMONADS

virulence, but in some instances lose their ability toagglutinate with specific antiserum.

Pure cultures of Mycobacterium tuberculosis strainsH37Rv and BCG survive several days in the solubleoil emulsions.

ADDENDUM

Recently we have observed that the source of inocu-lum and type of soluble oil used influences the survivalof Al. tuberculosis and S. pyogenes var. aureus. For ex-ample, when 10 g of known positive tuberculous spu-tum was added to sterile 100 ml amounts of differentsoluble oil emulsions, viable mycobacteria and staphy-lococci were isolated six weeks later from some emul-sions but not others.Work is under way to determine whether these solu-

ble oils serve as growth or maintenance media. Viru-lence studies and the fate of these organisms in thepresence of pseudomonads indigenous to oil emulsionsis being investigated.

REFERENCES

BENNETT, E. 0. 1956 Discussion by E. 0. Bennett of "cur-rent research in the bacteriology of soluble oil emulsions"by Pivnick et at., Lubrication Eng., 12, No. 5.

BENNETT, E. 0. AND WHEELER, H. 0. 1954 Survival of bac-teria in cutting oil. Appl. Microbiol., 2, 368-371.

DAVIS, J. B. AND UPDEGRAFF, D. M. 1954 Microbiology inthe petroleum industry. Bacteriol. Rev., 18, 215-238.

DUBOS, R. J. AND MIDDLEBROOK, G. 1947 Media for tuberclebacilli. Am. Rev. Tuberc., 56, 334-345.

DUFFETT, N. D., GOLD, S. H., AND WEIRICH, C. L. 1943 Nor-mal bacterial flora of cutting oil emulsions. J. Bac-teriol., 45, 37-38.

FENNER, F. 1951 The enumeration of viable tubercle bacilliby surface plate counts. Am. Rev. Tuberc., 64, 353-380.

LEE, M. AND CHANDLER, A. C. 1941 A study of the nature,growth and control of bacteria in cutting compounds.J. Bacteriol., 41, 373-386.

OKAWAKI, M. B. 1953 A study of bacteria in oils. SeniorThesis, University of Nebraska.

PAGE, C. G. AND BUSHNELL, L. D. 1921 Oil folliculitis. J.Ind. Hyg., 3, 62-67.

PIVNICK, H. 1952 The nutrition and factors affecting thegrowth of bacteria in soluble oils. Ph.D. Thesis, MichiganState College.

PIVNICK, H. 1955 Pseudomonas rubescens, a new speciesfrom soluble oil emulsions. J. Bacteriol., 70, 1-6.

PIVNICK, H., ENGELHARD, W. E., AND THOMPSON, T. L. 1954The growth of pathogenic bacteria in soluble oil emulsions.Appl. Microbiol., 2, 140-142.

PIVNICK, H. AND FABIAN, F. W. 1954 Coliform bacteria insoluble oil emulsions. Appl. Microbiol., 2, 107-110.

PIVNICK, H., SABINA, L. R., SAMUEL-MAHARAJAH, R., ANDFOTOPOULOS, C. K. 1956 Current research in the bac-teriology of soluble oil emulsions. Lubrication Eng., 12,No. 5.

SABINA, L. R. 1956 Studies of Pseudomonas species insoluble oil emulsions. M.S. Thesis, University ofNebraska.

SAMUEL-MAHARAJAH, R. The antagonistic relationship ofpathogenic bacteria and pseudomonads in soluble oilemulsions. M.S. Thesis, University of Nebraska.

ERRATAIn the paper by C. H. Bayley, "Some Auxiliary Effects of Textile Fungicides," Vol.

4, No. 2, March 1956:Page 78, Table 3-The data in the last three lines of the fourth and fifth columns

should be interchanged.Page 79, Line 4-The word "copper" at the end of the line should read "chromium."Page 79, Line 6-The word "copper" should read "chromium."

In the paper by Lloyd L. Kempe, Robert A. Gillies and Ronald E. West, "AcidProduction by Homofermentative Lactobacilli at Controlled pH as a Tool for Study-ing the Unit Process of Fermentation," Vol. 4, No. 4, July 1956:

Page 177-The first equation should read

dCA = kAdt

Page 177-The second equation should read

2 dCA dCB _Kdt dt

19561 299