AATCC 148-2015 Light Blocking Effect of Textiles and Related Materials: Photodetector Method.
1. Purpose and Scope
1.1 The test method measures the light blocking properties of textile and related materials using a photometer.
1.2 This method is applicable to all types of fabrics, including coated textiles and other textile-based constructions.
2.1 By measuring the amount of light from a test lamp, and the amount of light from the same lamp transmitted through a test material, the percent of light blocked by the material is determined. This repre- sents the material’s light blocking effect.
3.1 diffuse transmission n.—process by which incident light, while being transmitted through an object, is redirected or scattered over a range of angles.
3.2 light n.—electromagnetic radiation weighted by the luminosity function of the human eye.
3.3 light blocking, n.—the ability of a textile to prevent the transmission of light.
3.4 non-diffuse transmission, n.—process by which incident light is transmitted through an object in a rectilinear, straightthrough manner, without diffusion.
3.5 photometer, n.—an instrument used for measuring light 3.6 total transmission, n.—the amount of light transmitted comprising diffuse plus non-diffuse transmission.
3.7 transmission, n.—process by which incident light is transmitted through an object.
4. Safety Precautions NOTE: These safety precautions are for information purposes only. The precautions are ancillary to the testing proce- dures and are not intended to be all inclu- sive. 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 materials safety data sheets and other manufacturer’s recommendations. All OSHA standards and rules must also be consulted and followed.
4.1 Good laboratory practices should be followed. Wear safety glasses in all laboratory areas.
4.2 The manufacturer’s safety recommendations should be followed when op- erating laboratory testing equipment.
5. Uses and Limitations
5.1 The results may depend on the spe- cific light source used in the instrument. This is quoted as part of the report.
5.2 For materials of high light blocking effect, the method is limited by the ability of the system to measure very small amounts of light, in turn depending on the sensitivity of the instrument, together with the output of the light source used (see 14.3).
5.3 The test measures non-diffuse transmission through the material under test. It is designed to exclude diffuse transmission (scattered light) (see 14.1).
6.1 The measurement is of an SI-based quantity (lux), and the instrument should be calibrated to traceable standards at in- tervals recommended by the manufacturer, typically on an annual basis.AATCC 148 pdf download.