AATCC 17 pdf free download

AATCC 17 pdf free download.Wetting Agents, Evaluation of.
6. Test Solutions 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. Procedure 7.1 The diluted solution for test is poured from the liter volumetric flask into a 1500 mL beaker to ensure mixing. The solution in the beaker is then divided equally between two 500 mL graduated cylinders. If the more dilute solutions are tested first, the mixing beaker and cylin- ders need not be rinsed out and dried each time. The operator must wait after the cylinders have been filled until all bub- bles below the surface of the solution have risen to the top before the sinking tests are made. The operator may advantageously prepare solutions for 6 more cylinders while waiting for the bubbles to rise. Foam on the surface of the solution is removed either with a 100 mL bulb pi- pette or with an aspirator. Where there is little tendency for exhaustion of the wet- ting agent on the test skeins- practically always true for cotton- it is permissible to use the same diluted solution over again several times rather than to make a new diluted solution for each new skein. In this case only one 500 mL cylinder can be filled repeatedly from one liter of solu- tion of a certain concentration. 7.2 Since temperature often markedly affects wetting, standard temperatures of 25°C, 50°C， 70°C and 90°C have been chosen for testing so as to include the complete commercially useful range. It is most convenient to attain a temperature of 25°C merely by using water which has been brought to the correct temperature in a large pail. For tests at higher temperatures, heat the diluted solution for test in the mixing beaker to a temperature some- what above that required, pour the solu- tion into the cylinder and then allow it to cool back to the testing temperature. 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.AATCC 17 pdf download.