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Red No 4 stability
I made a tanning mousse and used FD&C Red NO.4 , BLUE No 1 and Yellow 5 to make brown, after 20 days the product turned from brown to green.
I suspect this is because of the FD&C Red NO.4 stability.
I recheck the formulation and noticed that my pH was at 6 instead of 4
Q: Does FD&C Red NO.4 need to be used at Ph 4 or below? I can’t find any information online that clearly state that it doesis there any other issues- that can cause a lack of stability in colour formulations
thanks for your help and contributions
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6 Replies
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@Emanuela Dyes are sensitive to pH change, especially Red #4 which is an acid dye. Other conditions can cause color fade/drift, and Red #4 is particularly sensitive to UV light. Can you try making another batch at pH 4 to rule out different pH being the cause? It’d be also nice to know if you have an antioxidant and a UV filter in your formula, and if your package is transparent or opaque.
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@ketchito thanks so much for your reply and confirming that Red 4 is an acid dye.
my packaging in opaque so no UV light contact.
Thanks again -
Are you using DHA as well in the tanning product?”
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DHA is very likely your culprit. Also, it reacts with some colorants.Formulate at a PH of 3-4. In water, DHA initially has a pH of 5.5 and which drifts down to 3-4 over time.
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Thanks Both for the support
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