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Looking for cosmetic chemist with BTMS troubleshooting experience
Had some issues with a new BTMS emulsified formula that works great, but won’t hold together. Have no prior experience with cationic emulsifiers so looking for a chemist to consult on or even fix the formula.
Base formula:Water, Behentrimonium Methosulfate (BTMS 25), Cetearyl Alcohol, Lactic Acid, Capric/Caprylic Triglycerides, Glycerin*, Triethanolamine, Cetyl Alcohol, Salicylic Acid, Niacinamide, Dimethicone (1000 cps), Stearic Acid.
Send me a PM!
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7 Replies
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While I have only used BTMS-50
Can you please post the % of each one? Maybe you’re using too much oils/silicones and too little BTMS? -
Could be!
6% BTMS-25
10% Fatty raws excl BTMS
2% Dimethicone cps1000 -
What is the purpose of the Triethanolamine? It is reacting with the stearic acid to form an anionic surfactant which is not compatible with the cationic surfactant. -
To upadjust pH to ~3.8, so you think it’s the culprit in combination with stearic acid? Any other buffers you’d recommend?
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What was the pH before adding TEA?
Was it even lower (more acidic)?
If so, you may wish to reduce acids: lactic, salicylic and stearic, as TEA is likely reacting with all of them as @ozgirl mentioned.You can check if they are insoluble
i.e. adding lactic, salicyclic and stearic acids in separate beakers, and adding TEA to each one of them, to see if an insoluble precipitate forms.
This can help spot the most troublesome ingredients, needing to be lowered or replaced.
A simple, 5 minutes experiment that will go a long way. -
Basic chemistry here, folks. Anionic organic salts and cationic organic salts (BTMS) do not play well together. Rid yourself of all the acids and the TEA, then you will be quite pleased with the result.
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5% L-Lactic Acid and around 3.5% TEA, so significant amounts. pH before adding TEA would be under 3 I reckon.
Stearic Acid (1%), Salicylic Acid (2%) or TEA arent’t charged so I don’t think they’re the culprit unless TEA is in fact reacting with Stearic Acid.
L-Lactic Acid is negatively charged and could be the problem, but I need the formula to be exfoliating, perhaps just reduce it to around 2% removing the need for much TEA at all?
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