Zinc oxide & rosemary

Hi All,
I need help please!

If I use the zinc oxide and rosemary CO2 together, the product's color change to purple ( at 5,5 ph is dark purple). This phenomenon occurs is not only in the emulsified product but also in water- free ( balsam) Can you help why make it?
thank you!


  • johnbjohnb Member, Professional Chemist
    As an initial thought, how pure is the zinc oxide?
    Rosemary extracts are phenolic and phenols characteristically react with iron to produce an intense red or purple colour. As iron is a common contaminant of ZnO it could be that reaction.
  • BobzchemistBobzchemist Member, PCF student
    How pH stable is the color?
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • Redox--at low PH zinc ions are likely reacting with Fe ions to discolor.I would first raise PH to 7 and observe color.
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