I have to admit I'm curious about this also. Would it hurt to try making a small batch out of it? If you were to figure out the average SAP value of all the oils in it and SF at least 5 %, then if it sets up and passes the PH test wouldn't that mean it's okay?
Aside from the zap for PH and the appearance of it, how does one really know their soap is safe? I mean, unless someone uses something really exotic in the recipe, excess lye is the only real danger, right?
This may make me sound dumb but I'm a soaping newbie and in my opinion the only stupid questions are the ones that go unasked so I'm throwing this out there anyways.
You can do it but it takes a little effort and some distilation equipment. Here are some instructions I found when I was thinking about buying some oils in bulk. If you are interested American Science Surplus has still kits on sale right now for about $75 bucks.
Materials Required:
1) Fats and Oils [coconut oil, sunflower oil]
2) Conical Flask
3) 100ml beaker
4) Weigh Balance
5) Dropper
6) Reflux condenser
7) Boiling Water bath
8) Glass pipette (25ml)
9) Burette
Reagents Required:
1) Ethanolic KOH(95% ethanol, v/v)
2) Potassium hydroxide [0.5N]
3) Fat solvent
4) Hydrochloric acid[0.5N]
5) Phenolphthalein indicator
Procedure:-
1) Weigh 1g of fat in a tared beaker and dissolve in about 3ml of the fat solvent [ ethanol /ether mixture].
2) Quantitatively transfer the contents of the beaker three times with a further 7ml of the solvent.
3) Add 25ml of 0.5N alcoholic KOH and mix well, attach this to a reflux condenser.
4) Set up another reflux condenser as the blank with all other reagents present except the fat .
5) Place both the flask on a boiling water bath for 30 minutes .
6) Cool the flasks to room temperature .
7) Now add phenolphthalein indicator to both the flasks and titrate with 0.5N HCl .
8) Note down the endpoint of blank and test .
9) The difference between the blank and test reading gives the number of millilitres of 0.5N KOH required to saponify 1g of fat.
10) Calculate the saponification value using the formula :
Saponification value or number of fat = mg of KOH consumed by 1g of fat.
Weight of KOH = Normality of KOH * Equivalent weight* volume of KOH in litres
Volume of KOH consumed by 1g fat = [Blank – test]ml