AATCC 79-2000 Absorbency of Bleached Textiles.
6. Test Specimen
6.1 A swatch or skein of bleached ma- terial can be used for this test, as long as the specimen can be spread tightly over an embroidery hoop.
6.2 Specimens sampled prior to drying should first be air dried. All specimens should be brought to moisture equilibrium in a standard atmosphere having a relative humidity of 65 ± 2% at 21 ± 1°C (70 ± 2°F) (see 10.1).
7.1 Conduct the test in a standard at- mosphere as defined above.
7.2 Mount the cloth (or smoothed-out, thick portion of yarn) in the embroidery hoop so that the surface is free of wrinkles, but without distorting the structure of the material.
7.3 Place the hoop about 10 ± 1 mm (0.375 in.) below the tip of the burette, and allow one drop of distilled or deionized water at 21 ± 3°C (70 ± 5°F) to fall on the cloth.
7.4 Using a stopwatch, measure the time required, up to 60 s maximum, for the surface of the liquid to lose its specular reflectance. This point is determined by hav- ing the hoop between the observer and a source of light—such as a window or lab- oratory spotlight—at such an angle that the specular reflectance of light from the surface of the flattened drop can be plainly seen. As the drop is gradually absorbed, the area of this tiny mirror diminishes and finally vanishes entirely, leaving only a dull wet spot. At this instant the watch is stopped and the elapsed time is recorded. When the wetting time exceeds 60 s, 60+ s should be recorded.
7.5 Take 5 readings.
8. Calculation and Evaluation
8.1 Average the 5 time readings. The shorter the average time, the more absorbent is the textile. Five seconds or less is generally considered to represent ade- quate absorbency.
9. Precision and Bias 9.1 Interlaboratory Study. Tests for ab- sorbency of bleached textiles were con- ducted in 1992, with 5 laboratories evaluating 7 fabrics. Participating laboratories were presumed to be performing the test method under statistical control, without verification.
9.1.1 The analysis of variance tech- nique was applied to the data set. The analysis is being retained for reference in RA34 committee files.
9.2.1 When two or more laboratories wish to compare test results, it is recom- mended that laboratory level be established between them prior to beginning test comparisons.
9.2.2 Critical differences for single fabric comparisons and for multiple fab- ric comparisons are given in Tables I and II, respectively.AATCC 79 pdf download.