Abstract
In continuation of an inquiry into the effect of microbial action and weathering on cotton fiber, experiments have been carried out to determine the relative responsiveness of certain fiber properties to the growth of fungi. Raw cotton fiber and unbleached cotton fabric were inocu lated and incubated for varying periods up to 28 days in a water-vapor-saturated atmosphere with each of three common fungi under pure-culture conditions, and various properties of the fiber and fabric were measured subsequently. In general, the aqueous-extract pH and the reducing- substance content of the incubated samples changed quickly and substantially, the former in creasing and the latter decreasing. Degree of swelling in 18% NaOH and Congo red values changed little during the first few days of incubation, but later increased progressively. Strength, as measured on fiber by the use of a Pressley breaker equipped with 1-mm.-gap jaws or on fabric by the 3-in. ravelled-strip method on a Scott tester, showed little or no decrease. Length, determined by the Suter-Webb sorter method, decreased moderately with one of the fungi, but little if at all with the other two. Wax content decreased, but only moderately. Cladosporium-incubated fiber became measurably and visibly darker. Absorption of the direct dye Chlorantine Fast Green by fiber incubated with Cladosporium and mercerized before dyeing increased markedly with increasing periods of incubation.
Incubation at 95% R.H. greatly slowed down the rate of change in pH and reducing-sub stance content as compared with results obtained in a saturated atmosphere and prevented change in the alkali-swelling response.
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