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Stearic-palmitic acid
Im trying to find stearic acid but it is always mixed with palmitic acid. Even if i find a seller that describs it as PURE stearic acid (INCI:STEARIC ACID) when i go to the SDS it shoes a mix of both of them. I dont understand it.
If because of any reason it would be normal, why inci only shows stearic acid?
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5 Replies
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Most raw materials are actually blends of ingredients even though they are list as single ingredients. This has to do with the way they are synthesized. If you want to make Stearic Acid you start with a blend of fatty acids. Most of that blend is C18 (stearic) but some percent will be C16 (palm), C14, C12, C20. For cosmetic ingredients it doesn’t make economical sense to separate the fatty acids more than they do. You’ll almost always get a blend in your final product even though most of it is Stearic Acid.
Here is a list of common oils they might use to make cosmetic raw materials. You can see they are a blend of lots of fatty acids. http://www.chempro.in/fattyacid.htm
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Thanks @Perry . I understand that, but why INCI is described as stearic acid if it is a blend?
I also have read a lot of INCI cosmetic products (final products) just listing stearic acid but not palmitic acid or any other fatty acid. Is that means that they used a pure version (i dont think so) or INCI is incorrect in that products?as example, in lotion crafter they list a blend of palmitic-stearic just as stearic (you can even read INCI: stearic acid):
http://www.lotioncrafter.com/stearic-acid-nf.html
But it is not just lotioncrafter. There is a big tendency to do this with Stearic acid
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Chalk it up to the vagaries of ingredient nomenclature. Here’s my opinion of what is going on.
The PCPC is responsible for approving INCI names. When picking names they have to balance two things, scientific accuracy and length of the name.
If scientific accuracy was all that matter they would have just used the IUPAC system and not created a new one. But those names are so long and complicated that they wouldn’t fit on the labels and no one would read them anyway so it defeats the purpose of labeling.
Also, nearly all ingredients are blends of different kinds of molecules. Naturally derived compounds have hundreds of component materials while synthetic ingredients might have the main reactant plus residual reagents and secondary reactions.
Now, the PCPC could have said that the INCI name of a material will list all it’s component materials. But you could imagine that this would make the ingredient lists rather long too. So, the PCPC decided they would ignore most residual ingredients and go for the most straightforward naming. This reduces accuracy but it maintains readability.
The other issue is that listing all the ingredients could be misleading. Take Stearic Acid for example. There is no pure stearic acid so it will be a blend of different acids and your INCI name would be:
INCI Name: Stearic Acid & Palmitic Acid & Lauric Acid & Myristic Acid
If this were the case, how would you differentiate a material that has 90% stearic acid (10% residuals) from one that has 20% stearic acid (80% residuals)? There would be no way to differentiate between Stearic Acid and Palmitic Acid.
All of the acid derived materials would have exactly the same name and formulators (and consumers) would have no way of knowing the difference.
So, it’s more clear for the INCI naming committee to just say that if something has >50% of an ingredient then it will be called that ingredient and the others will be ignored. This is further complicated by the fact that there are materials with source derived ingredient names (e.g. Cocamide DEA) and ones that are purposefully blended (Cetearyl Alcohol).
This ingredient naming is complicated. That’s my opinion anyway.
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Good explanation and I am agree that it is not practical to list “all” the ingredients forming a mixture but I was surprise as SDS of stearic acid used to be in most of retailers 55/60-40/45 stearic-palmitic. Nothing “residual”….anyway it is like you said: more than 50%…
Thanks!
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It becomes a matter of shopping around! I recently discovered that the Stearic Acid I was using has a Stearic Acid content from 42-47% and a Palmitic content of 52-58% yet is is called Stearic Acid NF (INCI: Stearic Acid). But my understanding is that it functions quite similarly to Stearic with different ratios but I was surprised to find that it had an SAP value higher than I had been using to calculate for my project. Corrections then needed to be made… If you have specific requirements, you need to be careful “shopping” and get the proper documentation from your potential supplier.
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