Ok, I checked every fat on soapcalc for stearic and palmitic and came up with the results shown below.Yes, this could certainly be done. Which fat do you recommend?
What I don't know is what the numbers actually represent. Is it a percent of the fat overall? At this point I am going to make the assumption that it's percent.
@DeeAnna correct me if I'm wrong.
Based on what I found, the best option would be to use Ucuuba butter if the end goal is to have absolutely no palmitic mixed in with the stearic. However, I'm cheap, so if I was doing it I would opt for the fully hydrogenated soybean and know that there is a small amount of palmitic mixed in with the resulting stearic.
I did find a source for the Ucuuba Butter and the cost is 36.25 for 1 lb. If the assumption is correct and the numbers here are percent, that would mean 4.96 oz of stearic from 1 lb of Ucuuba butter.
I found hydrogenated soybean on thesage 9.90 for 2 lbs. Using 1 lb to make soap and then break it down, would result in 15.68oz of stearic/palmitic combined, consisting of 12.16 oz stearic and 1.76 oz of palmitic.
For a purist that doesn't care about the cost and wants straight stearic - Ucuuba butter
For a non-purist that doesn't mind a small amount of palmitic, hydrogenated soybean oil
Oops, sorry @Johnez I forgot the Kokum butter
Kokum butter would be a good choice as well. You'd end up with close to pure stearic.
WSP sells Kokum for 13.66 lb.
That would amount to 7.36 oz. of stearic with a combined total of 8 oz. Stearic/palmitic.
The only question now that remains is how to best separate the stearic/palmitic from the soap.
Because I do only HP, I would think you could make a batch of soap with the fat of choice to saponification (yes, zap test needed here ). While it's still hot, add a solution of distilled water mixed with citric acid until the soap "breaks." Allow the resulting mixture to cool to around 150 F, then strain to remove the stearic/palmitic that should have solidified by then. Technically, if you can control the temperature while straining (this would be very very difficult to do IMO) you could allow to cool just below 156.7 and strain quickly to get just stearic? Don't know how feasible that would be as your tools would all need to be the same temperature.
Stearic - 156.7
Palmitic - 145.2
Oleic Acid - 61 F
I would think doing it right after it saponifies would make it faster/easier to get the stearic needed without any of the other fats.