Kosas is one of the most-talked about brands on TikTok, and the clean beauty brand is usually garnering snaps for their beloved formulas.
But if you type ‘Kosas’ into the app’s search bar, you’ll likely find alarming suggestions like ‘Kosas concealer mold’ and ‘Kosas mold’.
We had to do a double take when we first saw it, and evidently whistle-blower Lucinda McGarrity was equally horrified when she found out; “apparently Kosas products get filled with mould really, really quickly.”
“[I checked out the] Kosas mould Reddit as well and it was horrifying,” the TikToker explained to viewers.
McGarrity’s discovery sparked the curiosity of fellow TikToker and Cosmetic Chemist Jane Tsui, who said she ran to see what her Kosas concealer smelled like after seeing the video.
After inspecting it she concluded “it has a slightly stronger scent than most of my other concealers, but I wouldn’t say it’s rancid.”
Given Tsui’s professional expertise as a Cosmetic Chemist, she was able to explain where the confusion might have come from.
“I see a lot of people in the comments saying that because Kosas is a clean and natural brand they use less preservatives,” she said. “However, I wouldn’t say that statement is 100 per cent factual.”
“All products, whether ‘clean’ or not, have preservative efficacy testing,” she explained.
“This means that for every batch of concealer made they have to pass a micro test in order to release it, and I see here that Kosas is using potassium sorbate and sodium benzoate as their main source of preservation,” she went on to say.
Here’s where things get pear-shaped; “I as a formulator don’t think that’s enough,” Tsui admitted. “That’s just my opinion though.”
But you know what’s better than the opinion of one chemist? Two.
Tsui actually enlisted the help of another chemist/content creator to work out just how Kosas could be getting away with using so few preservatives in their formulas.
“[A product] can actually pass micro at the time of batching but fail later,” Tsui explained. “Some preservation systems are sometimes a little bit weaker than others.”
“This might have passed micro at the time of batching, but we don’t know if it passed micro at like three or six months.”
Before you throw out your Kosas products Tsui recommends holding onto them, just so long as they don’t give you an allergic or adverse reaction.
“I’m not saying all your Kosas products have mould in them,” she went on to say. “But I’d have to send this out to a lab to see how the preservation system is holding up.”
Briar is the Beauty Editor at BEAUTYcrew. Her 'down for anything' attitude has resulted in more than a handful of hair transformations, and she doesn't mind being used as a guinea pig for the industry's most unusual products and treatments. Her work has also appeared on Refinery29, Girlfriend and beautyheaven.