Dihydroxyacetone (DHA) is a water soluble alpha hydroxyl ketone that is the active in sunless tanning formulations. DHA reacts with amines, peptides, and amino-acids in the stratum corneum to generate brown polymers called melanoidins and after 2-6 hours a brown coloration similar to a tan is formed. (EU: Dihydroxyacetone | DHA)
1. 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.
2. Avoid using metal oxides (iron oxides, titanium/zinc oxides).
3. Avoid phosphates. Don’t use pH buffering agents, many are phosphate based.
4. Avoid incorporating any amine containing ingredient (amino acids, peptides, proteins, EDTA).
5. Avoid using alpha or beta hydroxy acids.
6. Avoid using oxidizing agents.
8. Add DHA to formulations at <40C.
9. Use an opaque packaging in order to avoid a UV-induced degradation of DHA.
10. Use low PH stable acryloyldimethyltaurate based polymers as thickeners, such as Aristoflex AVS by Clariant and Sepiplus S and Sepigel 305 by Seppic.
(EU: acryloyldimethyltaurate | Aristoflex | Sepiplus S | Sepigel 305)
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