Abstract
The dyeing of silk cloth with carthamin extracted from safflower (Benibana) gave different shade with three
organic acids, even though all dye baths were adjusted to pH=6.9. The cause of this color difference was studied by analyzing Kubelka-Munk function (KM-function) spectra of dyed silk cloth. The KM-function spectra were found to be composed by two spectral components, F0 and F0x. Theirmaximal absorptions were at 520 and 510 nm, respectively. The shade of dyed silk cloth depended on the both of relative strengths of the spectral components and the dyeing concentrations. The relative strength of the spectral component (F0) was arranged by the used organic acids as citric acid > acetic acid > Ubai, while the dyeing concentrations were arranged as acetic acid > Ubai and citric acid. The difference between the spectral components, F0 and F0x, was suggested to be caused by the degree dissociation of hydroxyl groups in carthamin. The dependence of the color difference of dyed silk cloth on the used organic acid, therefore, was considered to be attributed to the difference in acidity on the silk cloth.
