Coconut SAP value differences

[aharonys]

one table 0.183
second 0.184
third 0.191

amount of Lye for 100% percentage CO with 4% Fat with SAP as 0.191 is the same amount of 0% FAT with SAP value of 0.183.

what value do u use?

how can i determine the real SAP value for my oil ?
i thought of just making experience with ZAP tasting for 4% 3% 2% ...0% (maybe less who knows?)

but then, I cant be sure if the zap is from uncompleted saponification, or too much lie, or something else...

 

[The Efficacious Gentleman]

I have 0.183 on my list. I don't know which lists you have as one two and three, but the last one seems to be the outsider and I would consider it with a question mark

 

[Susie]

The issue is that they have sourced oils from different places to get those values. I am with Craig, eliminate the one that is way higher than the others. Then just pick a value from the remaining two and stick to it.

I use one lye calculator, Soapee.com, so that I get consistent results in my soaps. There is no proving that the CO I have is this value or that, but by using the same calculator over and over, I can adjust to whatever the SAP value is on that CO batch.

 

[DeeAnna]

Kevin Dunn in his book Scientific Soapmaking discusses how to do a test for saponification value. You would want to do this for every batch of fat if you really, really want to know the sap values, since they will vary over time. Fats come from natural sources and nature is not perfectly consistent, so this is not a "test once and you're done" kind of thing if you want that kind of accuracy.

You should also learn to test the purity of your NaOH and adjust your lye weight to correct for that. Most calcs assume NaOH is 100% pure, but that's unrealistic. Commercial NaOH direct from the manufacturer is never that pure, and the purity can only go downhill from there. If your soap recipes use a blend of fats, the errors in the sap values may average out, but the assumption that NaOH is 100% pure always adds an error in the direction of raising the superfat.

All that said, most of us pick a calc, learn to use it, and accept there is some inaccuracy involved with the sap values, the NaOH purity, our measurements, etc.

 

[aharonys]

Kevin Dunn in his book Scientific Soapmaking discusses how to do a test for saponification value. You would want to do this for every batch of fat if you really, really want to know the sap values, since they will vary over time. Fats come from natural sources and nature is not perfectly consistent, so this is not a "test once and you're done" kind of thing if you want that kind of accuracy.

You should also learn to test the purity of your NaOH and adjust your lye weight to correct for that. Most calcs assume NaOH is 100% pure, but that's unrealistic. Commercial NaOH direct from the manufacturer is never that pure, and the purity can only go downhill from there. If your soap recipes use a blend of fats, the errors in the sap values may average out, but the assumption that NaOH is 100% pure always adds an error in the direction of raising the superfat.

All that said, most of us pick a calc, learn to use it, and accept there is some inaccuracy involved with the sap values, the NaOH purity, our measurements, etc.

that was my second question, "how to measure the lye purity ?"
I am sure that my NaOH is not 100% as i see it "drinks" water from the air every time i open the box..

so basically, I CANT really relies on calculators to understand how much superfat i have in my soap.

so. I'm still missing the info how to get a real 0% super fat.
is the info from the book is a big secret or complicated ? or you can describe it here?

 

[DeeAnna]

It's basic college chemistry -- absolutely no trade secrets -- but too lengthy and complicated to reproduce it here. You'd do him and me both a favor to just buy his book.

That said, there's a less accurate but much easier method that Dunn presented recently to check NaOH or KOH purity. I show the details here: http://classicbells.com/soap/purityCheck.html