AATCC 79 pdf free download

AATCC 79 pdf free download.Absorbency of Bleached Textiles.
1. Purpose and Scope
1.1 Absorbency is one of several factors that determines the suitability of a fabric for a particular use, as in the case of gauze or toweling. It is important in fabrics that are to be dyed. since the completeness and uniformity of the dyeing are dependent upon the absorbency. Where fabrics are to be given resin or other specialized finishes, absorbency is a factor to be considered. Wettability or absorbency of textile fabrics or yarns can be determined by this test method.
2. Principle
2.1 A drop of water is allowed o fall from a fixed height onto the taut surface of a test specimen. The time required for the specular reflection of the water drop to disappear is measured and recorded as wetting time.
3. Terminology
3.1 absorbency, n.—the propensity of a material to take in and retain a liquid. usually water, in the pores and interstices of the material.
4. Safety Precautions
NOTE: These safety precautions are for information purposes only. The precautions are ancillary to the testing procedures and are not intended to be all inclusive. It is the user’s responsibility to use safe and proper techniques in handling materials in this test method. Manufacturers MUST be consulted for specific details such as material safety data sheets and other manufacturer’s recommendations. All OSIIA standards and rules must also be consulted and followed.
4.1 Good laboratory practices should be followed. Wear safety glasses in all laboratory areas.
5. Apparatus
5.1 Embroidery hoop with a 150 mm
(6 in.) or more diameter.
5.2 Burette, delivering 15-25 drops of water per milliliter.
5.3 Stopwatch.
5.4 Burette stand.
6. Test Specimen
6.1 A swatch or skein of bleached material 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 ± I °C (70±2°F) (see 10.1).
7. Procedure
7.1 Conduct the test in a standard atmosphere 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 having the hoop between the observer and a source of light—such as a window or laboratory 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 adequate absorbency.AATCC 79  pdf download.