Dyeing properties ofCI AcidBlue 193 and the non‐equivalent properties ofCI AcidBlack 194 produced by different manufacturers

This paper presents the results of research conducted into the colour properties of commercial metal complex dyes CI Acid Blue 193 and CI Acid Black 194. Three chromium( III ) complexes with different colours were identified using thin‐layer chromatographic analysis and then separated by preparative chromatography. It was found that colour differences of the examined dyes depend on the ratio of the three components in CI Acid Blue 193 and CI Acid Black 194, and that these differences are typical for each of the commercial products. The colour differences of the components were expressed as Δ S , calculated as the difference in the areas under the absorption curve of the individual components in the range 400–700 nm after spectrum normalisation. The UV ‐vis spectroscopic and CIELAB colorimetric properties (at 1% owf on polyamide) of eleven samples of CI Acid Black 194 were investigated. From these results, the proportions of the three components were derived. Theoretically, dyes sold under the same CI name are interchangeable. In practice, the obtained colour of the dyed material is different owing to the difference in composition namely the ratio of the components in the tested dyes. Consequently, the result of polyamide dyeing with the studied dyes CI Acid Blue 193 and CI Acid Black 194 is a redder or greener hue. It has been concluded from these findings that the production of identical dyeings may be impossible when dyes from different sources are employed.