抄録
The visual ratings on fastness of dyeings are influenced by many factors such as mental state of assessor, judging conditions, and so on. The variation factors of visual rating were examined. 307 sheets of stained cloth specimen were prepared by rubbing on 82 kinds of commercial clothing leather. The staining of the specimen was assessed with the Grey Scale by 26 assessors, making 7982 assessments in all.
The agreement between the average and individual ratings within ±0.5 rating grade was found to be about 94% for all assessments.
The formula which showed an extremely high correlation coefficient between the rating and the colour difference of the Grey Scale was proposed. The formula made it possible to calculate the rating of the stained specimen.
By comparing the visual and calculated ratings for all assessors, it was found that the assessors have an inherent rating criterion which gave good reproducibilities to their own assessments. However, the internal criterion differed from each other too greatly among assessors. The dispersion of visual ratings was broadened with increase in the colour difference of the stained specimen. This is mainly due to the difference in the internal rating criterion among assessors.
The difference threshold also increased with increase in the colour difference of the stained specimen. However, the difference threshold showed minor effect on broadening the dispersion of visual ratings.
The cloth grey scale was prepared for the purpose of decreasing the difference in the internal criterion among assessors. It should be noted that the dispersion of visual ratings is fairly improved by using the cloth grey scale.
