AATCC 203 Light Blocking Effect of Textiles: Spectrophotometric Method

Purpose of Test

This test spectrophotometrically determines the light-blocking properties of textile from light passing through windows and light seen on the darkened side of the textile, like a curtain or drape.

The spectrophotometric method is applicable to various fabric types:

  • Knits
  • Woven
  • Nonwoven
  • Fabrics taken from end product items

This test is not recommended for fabrics with mesh structures with holes bigger than 3mm across.

Terminology Defined

Light-Blocking – The ability of a textile to prevent light transmission.

Light transmission – The process by which the light is transmitted through the test fabric.

Spectrophotometry – A method used to measure the amount of chemical substance that absorbs light through measuring the light intensity when a beam of light passes through textile.

Spectrophotometer – The measurement tool used to identify the amount of light intensity that passes through the textile.

Spectrophotometer (Image Source: Scilogex)

Test Method

Materials Used for Test

  • Test specimen
  • Spectrophotometer
  • Means of covering light reflectance with white standard tile
  • Means of blocking light transmission

Testing Procedure

The test specimen undergoes light transmission using a spectrophotometer. The transmission is recorded and the light-blocking property is determined using standard test calculations.

Test Procedure (Summary)

Part 1: Operational checks: The spectrophotometer is checked for total light transmission with no light blocking and with opaque light blocking. 

Part 2: Testing the specimen: The test specimen is placed on the spectrophotometer and undergoes light transmission. The light transmission is recorded and standard calculations are made to determine light-blocking properties.

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