Test Method for Transmittance or Blocking of Erythemally

AATCC 183-2020 pdf free.Test Method for Transmittance or Blocking of Erythemally Weighted Ultraviolet Radiation through Fabrics.
Calibration. Calibrate the spectra — photomctcr or spectroradiometer according to manufacturer instructions. The use of physical standards is rcconiinended for validating ihc measurement of spectral transmittance.When running a wet sample place the plastic wrap over the port and repeat calibration.
Wavelength scale. Calibratc the wavelength scale of the spectrophotome. ter or spectroradiorneter using the spectral emission lines of an electrical discharge in mercury vapor. The wavelength calibration of a spectrophotometer can be performed using the absorption spectra of a holmium oxide glass filter. Reference wavelengths for both mercury arc emission and holmium oxide absorption arc provided in ASTM E275.
Transmittance scale. Set the transmittance scale to a 100% value by operating the instrument without a sample in the optical path: therefore. referenced to air. The 0% value can be subsequently verified by fully obstructing the sample beam path with an opaque mate. riaL Validate the linearity of the transmittance scale by means of either calibrated neutral density filters or calibrated perforated screens supplied by the instrument manufacturer or standardizing laboratories.
Verification checks on the opera. lion of the test and the apparatus should be made and kept in a log. The use of a verification fabric is recommended at least once a month unless no testing is to be performed that month.
Test a minimum of two (2) specimens from each sample. one each for the wet and the dry testing. Cut each specimen at least 50 x 50 mm (2.1) x 2.0 in.) or 50 mm (2.0 in.) in diameter. Avoid distorting the specimen during preparation and handling.
Should the fabric have areas of different colors or structure, test each color or structure if its size is sufficient to CO%CT the measuring port.
See Appendix AS for specimens exhibiting fluorescence.
For dry specimens, bring to moisture equilibrium in a standard atmosphere according to ASTM D1776. Use conditions listed for Textiles, General in Table I of the standard.
the sample transmission port opening in the sphere.
Make one UV transmission measurement with the specimen oriented in one direction, a second measurement at 0.79 rad (45°) to the first and a third at 0.79 rad (450) to the second. Record the individual measurements.
On multicolored specimens, determine the area of highest UV transmission and make the three measurements at 0.79-rad (45°) rotation intervals in that area.
Weigh the test specimen. Thoroughly wet out the specimen in distilled water by placing it flat in the bottom of a beaker and theii pour distilled water into the beaker until the specimen is covered. Allow the specimen to remain submerged for 30 minutes. Press and move the specimen from time to time to ensure a good and uniform penetration. Prepare only one specimen at a time.
Bring the wet pick-up to 140 ± 5% by squeezing the wet specimen between blotting paper through a hand wringer or similar convenient means (such as squeezing between two glass rods). If the fabric has low moisture absorption, repeat the soaking and wringing steps. Note, some samples may not be capable of achieving the specified wet pickup such as tightly woven synthetic fabrics.AATCC 183 pdf download.Test Method for Transmittance or Blocking of Erythemally