sos change of color

I would really appreciate it if you could give any advice about a production issue that I came across.
A simple recipe of a concealer stick, with carnauba wax, beeswax,ozokerite, paraffinum liquidum,castor oil, and pigments pre-despersed in castor oil.
we unfortunately 3 months after the production, have complains that the color looks beige, but it relly writes like pink.
I assume that we have oxidation, even if I used BHT and tocopherol..
Any advice would be appreciated.


  • @mayachem, did you do a real time stability test? That can usually take about 3 months to do properly?
    Dr. Catherine Pratt
    (B.Sc with HONS I , Ph.D Analytical/Organic Chem and Microbiology), Cosmetic Chemistry IPCS)
  • chemicalmattchemicalmatt Member, PCF student, Professional Chemist
    Somewhat weird. Using only iron oxides?
  • If it looks different on the stick than on the hand, that doesn't indicate oxidation to me. What about writing on paper or not-skin? Does the color also appear pink there?
  • Did you mill it? Probably your red IO coming out.
  • You can also buy pre dispersed pigments if you don't have a mill.
  • Have you cut a bullet up? This is very common when mixing iron oxides in castor oil and wax blends. Injection and cooling stage your red is sinking down in my opinion. I bet the bottom of the bullet will be less so.. 
  • @Tal025 ; what do you mean by injection and cooling stage?It is a filling process issue?
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