I'll preface this thread by stating I've learned a lot in this little journey. Biggest lesson is you cannot trust soap calcs to always be right. This stearic example is one of a few I have personally dealt with, however there are some other fats that are problematic. Second lesson is you cannot trust hearsay or popular belief. For some time I operated under the wrong information. This thread is mainly to make it utterly clear to everyone. Many already know the info in this thread, but know some here do not, and some who come in the future may not have that knowledge either-so this thread is for them. Unfortunately, this thread will probably die and we'll have to keep bringin up that stearic acid numbers are wrong in soap calcs and to factor that in...just like ResolvableOwl did for me long ago. However, I hope it sticks around in the greater group memory. Anyway, here goes nothin:
Every single soap calc is wrong when it comes to listing "stearic acid" and it's fatty acid composition. Nowhere can "Stearic Acid" be found with a Stearic Acid fatty acid content of "99%." None.
Soy wax is not fully hydrogenated soybean oil, and therefore does not have 87% stearic acid.
Every single soap supplier carrying stearic acid is selling a product that is a 50/50 mix of stearic acid and palmitic acid. Not a single soap supplier carries anything close to pure stearic acid (ie-not a product that is half palmitic acid).
I have tried over the course of the past few weeks to find a single solitary source of pure stearic acid. My search was fruitless so I modified the requirement that the final ingredient has to be a majority stearic acid, henceforth referred to as SA. Anyway, something in the range of 80-90% would have been ideal, heck I would have been satisfied with anything that shows a majority SA over PA. However it simply does not exist. Every single COA or document that lists the breakdown of fatty acids shows a roughly even distribution b/w SA and PA.
I have emailed promising suppliers. Soap suppliers and lab suppliers. I have pored through COAs and other documentation. Many soap companies are forthcoming and perfectly list their FA makeups, others do not. I don't begrudge any of them, as this seems to be industry practice. Some soapers have made the assumption that what is listed as "pure stearic acid" is in fact made up of 100% stearic acid in it's fatty acid profile, however that is not an assumption that satisfies my curiosity without an attached document that shows the explicit fatty acid composition, specifically stearic acid and palmitic acid. "90% pure," "100% stearic acid," "99% pure" are most likely referring to the purity of the substance, not the actual stearic acid content. If a final product that is "47% stearic acid, 47% palmitic acid, 1% myristic acid, 1% lauric acid" can be labeled as stearic acid, calling it 90% stearic acid means it's got 10% of random things like ash, water, other matter, etc. and is not referring to the SA fatty acid content.
If anyone is curious to take up the search, here's some further info:
CAS 57-11-4 is the unique chemical ID number for SA.
SA can be derived from palm, soy, beef tallow, rapeseed oil.
SA sources other than "Stearic Acid" include beef tallow, many butters (Shea, cocoa, mango, sal, and notably kokum). Butter sources generally have a very favorable SA : PA ratio, however generally are in the 40-50% range.
I did find exactly one study that some purport to have used pure SA. Sigma Aldrich W303518 is that product, however I've not seen any documents showing a clear fatty acid break down. What's interesting is the paper using the stuff in a diet study was specifically designed to test stearic acid fatty acid. It is promising, however the prices on the stuff are pretty outrageous.
Fully hydrogenated soybean oil may very well be a source of high stearic acid content. I've yet to find a source however. Soy wax is not fully hydrogenated soy wax however, and unfortunately is not 87% stearic acid as @Mobjack Bay has demonstrated in her threads (search it). If you happen to find a soy wax that isn't GW 415 or any of the common ones out there right now, check the iodine value. If it's anything near 0 it very well may have a super high stearic content.
So why does it matter? I started this search when reading things like SA is less soluble in water than PA. SA is more stable. SA is harder to lather. And more. Clearly some people feel there's a difference, so I set out to see if it could be demonstrates through isolation experiments. More importantly though is accuracy in our hobby, and for some our business. SAP values and FA content we assume to be true but are not can affect our final product. Worse it can cause us to make *other* faulty assumptions. I think this wrong info has persisted for too long, and though correct info has been passed along by many and often here, I think it's worthwhile to dedicate a thread to this issue.
Some docs and stuff:
Hydrogenated soybean oil
https://www.researchgate.net/public...rtening_Oils_via_Hydrogenation_of_Soybean_Oil
Every single soap calc is wrong when it comes to listing "stearic acid" and it's fatty acid composition. Nowhere can "Stearic Acid" be found with a Stearic Acid fatty acid content of "99%." None.
Soy wax is not fully hydrogenated soybean oil, and therefore does not have 87% stearic acid.
Every single soap supplier carrying stearic acid is selling a product that is a 50/50 mix of stearic acid and palmitic acid. Not a single soap supplier carries anything close to pure stearic acid (ie-not a product that is half palmitic acid).
I have tried over the course of the past few weeks to find a single solitary source of pure stearic acid. My search was fruitless so I modified the requirement that the final ingredient has to be a majority stearic acid, henceforth referred to as SA. Anyway, something in the range of 80-90% would have been ideal, heck I would have been satisfied with anything that shows a majority SA over PA. However it simply does not exist. Every single COA or document that lists the breakdown of fatty acids shows a roughly even distribution b/w SA and PA.
I have emailed promising suppliers. Soap suppliers and lab suppliers. I have pored through COAs and other documentation. Many soap companies are forthcoming and perfectly list their FA makeups, others do not. I don't begrudge any of them, as this seems to be industry practice. Some soapers have made the assumption that what is listed as "pure stearic acid" is in fact made up of 100% stearic acid in it's fatty acid profile, however that is not an assumption that satisfies my curiosity without an attached document that shows the explicit fatty acid composition, specifically stearic acid and palmitic acid. "90% pure," "100% stearic acid," "99% pure" are most likely referring to the purity of the substance, not the actual stearic acid content. If a final product that is "47% stearic acid, 47% palmitic acid, 1% myristic acid, 1% lauric acid" can be labeled as stearic acid, calling it 90% stearic acid means it's got 10% of random things like ash, water, other matter, etc. and is not referring to the SA fatty acid content.
If anyone is curious to take up the search, here's some further info:
CAS 57-11-4 is the unique chemical ID number for SA.
SA can be derived from palm, soy, beef tallow, rapeseed oil.
SA sources other than "Stearic Acid" include beef tallow, many butters (Shea, cocoa, mango, sal, and notably kokum). Butter sources generally have a very favorable SA : PA ratio, however generally are in the 40-50% range.
I did find exactly one study that some purport to have used pure SA. Sigma Aldrich W303518 is that product, however I've not seen any documents showing a clear fatty acid break down. What's interesting is the paper using the stuff in a diet study was specifically designed to test stearic acid fatty acid. It is promising, however the prices on the stuff are pretty outrageous.
Fully hydrogenated soybean oil may very well be a source of high stearic acid content. I've yet to find a source however. Soy wax is not fully hydrogenated soy wax however, and unfortunately is not 87% stearic acid as @Mobjack Bay has demonstrated in her threads (search it). If you happen to find a soy wax that isn't GW 415 or any of the common ones out there right now, check the iodine value. If it's anything near 0 it very well may have a super high stearic content.
So why does it matter? I started this search when reading things like SA is less soluble in water than PA. SA is more stable. SA is harder to lather. And more. Clearly some people feel there's a difference, so I set out to see if it could be demonstrates through isolation experiments. More importantly though is accuracy in our hobby, and for some our business. SAP values and FA content we assume to be true but are not can affect our final product. Worse it can cause us to make *other* faulty assumptions. I think this wrong info has persisted for too long, and though correct info has been passed along by many and often here, I think it's worthwhile to dedicate a thread to this issue.
Some docs and stuff:
Hydrogenated soybean oil
https://www.researchgate.net/public...rtening_Oils_via_Hydrogenation_of_Soybean_Oil
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