One hair-dye sample recorded a pH of 10.4, above the mainland industry recommendation of 2.5 to 9.5, and could irritate skin, the Consumer Council said.
The Consumer Council tested 24 products: nine non-oxidative dyes and 15 oxidative dyes bought mainly from personal-care, beauty-supply and supermarket outlets. The assessment covered chemical safety, label transparency, colour performance and how well colour lasted after washing.
Twelve of the oxidative products contained between one and four detected sensitising substances. The quantities complied with the mainland Chinese and European requirements used in the assessment. None of the samples contained lead, cadmium, mercury or banned sensitisers. PTD was the most frequently detected sensitiser, found in 10 samples at concentrations ranging from 0.04% to 0.45%.
The information on the packaging was less consistent. Only seven samples gave detailed ingredient information in English on the bottle or packaging, with some providing it only in Japanese or other languages. Among the 12 samples containing sensitisers, nine clearly and completely listed the relevant ingredients; the other three did not label the relevant Part II poisons or their concentrations as required under Hong Kong’s Pharmacy and Poisons Regulation.
Performance varied by product type. Black oxidative dyes generally coloured hair well and retained their colour after washing, while some brown dyes performed less consistently. Non-oxidative dyes generally needed to be used one to three times within a week, followed by more frequent touch-ups to maintain the colour.
A HK$30 Revlon Colorsilk Beautiful Color black sample received the highest five-point safety rating and was identified as the best-value product in the test. For shoppers covering grey hair, the Consumer Council advised checking the package image showing the expected colour result and the stated suitable hair colour, as some products may not fully cover grey hair or may not be suitable for it.