Home Cosmetic Science Talk Formulating Color and makeup Red No 4 stability

  • Red No 4 stability

    Posted by Emanuela on September 14, 2021 at 11:37 am

     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 does 

    is there any other issues- that can cause a lack of stability in colour formulations 

    thanks for your help and contributions 

    Emanuela replied 2 years, 9 months ago 3 Members · 6 Replies
  • 6 Replies
  • ketchito

    Member
    September 14, 2021 at 12:01 pm

    @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.

  • Emanuela

    Member
    September 14, 2021 at 1:28 pm

    @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 

  • Microformulation

    Member
    September 14, 2021 at 1:36 pm

    Are you using DHA as well in the tanning product?”

  • Emanuela

    Member
    September 16, 2021 at 1:25 pm
  • Microformulation

    Member
    September 16, 2021 at 3:30 pm
    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.

  • Emanuela

    Member
    September 17, 2021 at 12:42 pm

    Thanks Both for the support 

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