抄録
When the whiteness of a fabric is measured, the test piece used generally piles up with two or three sheets of fabric. However, the reason for this piling remains unclear.
This paper examines the effect of the number of piled up fabrics of a test piece on its apparent reflectivity, which is closely connected to its whiteness, using an analytical model. Eight plain weave fabrics provided by Nakao Filter Co. Ltd. were prepared as samples. They were undyed and made of different fiber species. Using a color analyzer model CA-35, produced by Murakami Color Laboratory Co. Ltd., the reflectional spectra of the test pieces in the visible light range were measured as a function of the number of piled fabrics.
The results showed that the apparent reflectivity of test pieces increased as the number of piled up fabrics increased, then gradually tended to saturate for all wave lengths, with faster saturation rates being observed for lower wave lengths and violet colors. Experimental data were further analyzed under a simplified assumption of the optical behavior of fabric layered into a test piece. Thus, characteristic coefficients of reflection and transparency were estimated for each sample. Previous values ranged from about 40% to 50%, while later values were about 90%. Moreover, it seemed that the characteristics of reflection were determined by two components; one might be from the surface area of a fabric, the other from its interior.
