Effect of Light upon Wool

Abstract

It is shown that comparative diffuse reflectance measured simultaneously on test and control specimens with a recording spectrophotometer affords a sensitive measure of color changes by light in undyed wool fabrics, especially of the “orange dip” caused by ultraviolet at 254 m μ. For this purpose comparative reflectance was found to be much more sensitive than absolute or relative reflectance or than comparative or simple transmittance. Transmittance in an immersion liquid, o-dichlorobenzene, was the least sensitive. An expression for calculating transmission from reflectance values is derived and applied. Optical properties of three fabrics are compared for the above uv and visible region.