AATCC 17:1999 pdf download.Wetting Agents, Evaluation of
6.1 Stock solutions of the agents to be tested are normally prepared to contain 50.0 g of agent per liter unless the solu- bility is so poor that less must be em- ployed. The wetting agent is first thor- oughly dissolved in about a quarter of the necessary distilled water at a temperature above 80°C and is then diluted to the final volume with cold distilled water. Aliquot portionsof5, 7, 10, 15, 25, 35, 50, 75 and 100 mL of the 5% stock solution taken with delivery bulb pipettes and diluted with suitable water (see 10.4) to 1000 mL correspond, respectively, to concentra- tions of0.25, 0.35, 0.50, 0.75, 1.25, 1.75, 2.50, 3.75 and 5.00 g of wetting agent per liter. This range of concentrations is suffi- cient for the study of any commercial product.
7.3 For a determination, a 5.00 g skein of yarn is folded enough times to form a loop 45.7 cm around. A 91 .4 cm skein is most convenient and can be formed into a 45.7 cm loop with only 2 folds; a 137.2 cm skein requires 3 folds; a 182.9 cm skein, 4 folds and a 228.6 cm skein re- quires 5 folds. The hook with its anchor is fastened at one end of the folded skein and the skein is cut through with shears at the opposite end. The cut skein is drawn through the fingers when testing wetting agents in order to make it more compact. Any threads which have been tied around the skein to correct its weight are folded into the skein near the hook. The skein is held in one hand with the anchor dan- gling into the wetting solution contained in the 500 mL graduated cylinder. A stop- watch held in the other hand is started just as the skein is released into the solu- tion and it is stopped when the buoyant skein definitely starts to sink to the bot- tom of the cylinder. The skein before sinking must be entirely covered with sO- lution and yet it must possess enough buoyancy from the air within the yarn to keep the linen thread taut between the an- chor and the hook (see Fig.1). The aver- age of at least four determinations of sinking time should be obtained for each concentration of wetting agent. An aver- age deviation of 10-12% in sinking time may be expected (see 10.5).AATCC 17 pdf download.