Dear Valerie: My foundation formula is getting more orange over time. Is there something I should be doing in my formulation to avoid the color shift?
— Orange You Glad It Ain’t Banana

Dear Orange,

While I have worked in color cosmetics, I haven’t had the longevity required to be well-versed in the stability nuances that come with day in and day out lab experience. Fortunately (or unfortunately?) I have faced this issue in the past and been able to consult with Jane Hollenberg, the leading expert in cosmetics. 

As an aside, if you aren’t familiar with her out of print text, Color Cosmetics: A Practical Guide to Formulation, please try to get your hands on one! I had the opportunity to review the book for Chemists Corner upon its release in 2016. Ms. Hollenberg has additionally updated the second edition of Edward Faulkner’s text, Coloring the Cosmetic World: Using Pigments in Decorative Formulations, which is also an excellent resource currently available for purchase.

Back to our orange conundrum. It’s a common perception in the online world that orange shift comes from pH drift or oxidation. Iron oxides are relatively stable to heat in ordinary user conditions, and the pH of most foundation formulations are in a suitable range to avoid pH-caused drift, which occurs when black iron oxide is below pH 5.5 (it shifts to red). In my situation, the red iron oxides weren’t getting adequately wetted, so they wetted out over time in stability, causing the cream to shift orange and darker in appearance. The same thing can happen when it’s applied to skin; the sebum from skin can further wet out the red iron oxides. 

There are also varying tones of red iron oxides, depending how much reduced iron is present. Some iron oxides may appear more yellow, others cooler. The more yellow the iron oxide, the more it tends to shift the formulation orange in tone, which could further exacerbate your problem. This deeply illustrates the need to maintain a consistent supplier, have solid incoming QC procedures, and an excellent color matcher on staff.

You can find more of Valerie George’s formulation insights here.

Valerie George

askvalerie@icloud.com

Valerie George is a cosmetic chemist, science communicator, educator, leader, and avid proponent of transparency in the beauty industry. She works on the latest research in hair color and hair care at her company, Simply Formulas, and is the co-host of The Beauty Brains podcast. You can find her on Instagram at @cosmetic_chemist or showcasing her favorite ingredients to small brands and home formulators at simply-ingredients.com