Dear Valerie: Does every formula need a chelating agent? I have been reviewing all the water-based formulas my company makes and noticed all of them have some variety of EDTA. We’re using deionized water, so it seems like overkill. 

—METAL HEAD

Dear Metal:

I can see how one may think it’s overkill to add EDTA. It’s an ingredient that complexes with metal ions, if using a water source that has been stripped of its metals. No metals, no chelation necessary, right? 

I try to operate with a better-safe-than-sorry mindset. No process is fool proof. Even though deionized water has had all its ions removed, there is opportunity to reintroduce metals during the manufacturing process. Your products are manufactured in metal tanks and use metal implements during processing. Even with routine passivation of equipment, there is opportunity for trace metals to enter the batch over time.

On the topic of passivation, I’m surprised how few companies passivate their manufacturing equipment. But I’m not surprised how few chemists passivate their stainless steel lab ware. It’s especially crucial if making products that would be dangerous to the consumer if metals were present (hair color). Or, if working with ingredients that can complex with metal ions, rendering them useless (caprylhydroxamic acid, which turns a cute pink, a harbinger of micro headaches).

Make a Resolution

I routinely work with alkaline products so skipping routine passivation is not even an option. It’s not too late in the New Year to start a resolution—how about you join me at the close of every quarter to passivate your stainless-steel beakers, propellers and shafts?

We can’t forget about packaging either! Pumps can have metal springs on the interior that—depending on the quality of the pump—can come into contact with the product. I once worked at a brand that had pumps that would rust and leech into the product if the consumer reused the pump too many times. I sure was thankful for tetrasodium EDTA.

The bottom line is metal ions can be pesky when it comes to microbial growth and the shelf life of the product. In my risk-averse mind, it doesn’t hurt to put a chelating agent in to avoid negative outcomes. They are used in relatively small quantities, don’t add much to the cost of goods and aid in preservation. It also gives you peace of mind when it comes to your PET results. If you’re concerned about their environmental persistence or meeting your retailer standards, there are environmentally friendlier options to choose from. Bottom line, I recommend using them!

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