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Exotic fats that don't have SAP value

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Primrose

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What do you do when you want to play around with a bizarre fat but you can't find a SAP value? I'm getting some kangaroo tallow ...
 

DeeAnna

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Sometimes you can make a reasonable guess-timate about an unknown sap value by looking at fats you think are similar. If the fat is hard at room temp, look at fats that are hard at room temp (beef tallow). If the fat is soft at room temp, look at fats that are similar (lard for example).

Here are the animal body fats I have in my database with their NaOH saponification values. You could pick one, as TheGecko suggests, or go with the average. Either choice would be a reasonable guess.

Regardless of what you chose to do, keep in mind the sap values for these fats are all reasonably close to each other. Assuming kangaroo fat is reasonably similar to these fats, the largest error is still tolerably small (6% or less).

Another thing to keep in mind -- If your soap contains other fats whose sap values you are confident about, that will also reduce the error.

Fat ... NaOH Sap Value

Chicken Fat 0.139
Duck Fat, flesh and skin 0.138
Emu Oil 0.135
Goat Fat 0.137
Goose Fat 0.137
Horse oil 0.140
Lard 0.142
Mink Oil 0.140
Rabbit Fat 0.143
Tallow, Bear 0.139
Tallow, Beef 0.137
Tallow, Bison 0.142
Tallow, Deer 0.139
Tallow, Goat 0.137
Tallow, Human 0.140
Tallow, Sheep 0.139

Average 0.139
Minimum 0.135
Maximum 0.143
 

DeeAnna

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Never seen the movie (nor do I want to!), but yeah I gather that's the gist.

I should have deleted that sap value, but I obviously didn't take the time to proof the list all that well when copying it out of my notes.

The sap value of human fat gets talked about here from time to time. Ick, ewww, squick alert -- don't read this thread if you're even a little squeamish about this topic -- https://www.soapmakingforum.com/threads/useful-or-useless-information.41436/
 

TheGecko

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Never seen the movie (nor do I want to!), but yeah I gather that's the gist.

I should have deleted that sap value, but I obviously didn't take the time to proof the list all that well when copying it out of my notes.

The sap value of human fat gets talked about here from time to time. Ick, ewww, squick alert -- don't read this thread if you're even a little squeamish about this topic -- https://www.soapmakingforum.com/threads/useful-or-useless-information.41436/
Well I have enough [fat] to clean a small island nation. LOL
 

Cosmo71

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So happy to see this thread. I was gifted some lovely bear fat yesterday and wondered about the Sap value....took me two seconds to find it! Now to render the fat.
 
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