I’m trying to make soap with my high school chem kids, and we’ve been striking out using the recipes we’ve found on the net. Does someone here have a sure-fire recipe that’s personally verified? These are pretty bright kids, and they’re getting weird goops even when putting their heads together.
I guess renting *Fight Club *is out of the question… 
A 1908 text The Handbook of Soap Manufacture
It goes into much detail and may help you decide what to do to not have soft soap. I wish i could ask somebody I know about it, because she was really into making soaps, but I can’t. I remember she did say that oils produce a soft soap.
I haven’t done it yet as I haven’t had the time, but in my search for good soapmaking recipes, I found two very highly recommended websites:
Paging bodypoet!
Our own Doper bodypoet is a soap-maker, and makes very nice soap of many varieties.
Hiya. I had my own soap business for a couple years and several of us in the biz swore by the Magic Mountain Sage lye calculator, with one exception: Reduce the water by 1/3. Now looking at the page I see they’ve “adjusted the water to give a range of values” so I’m not sure what they mean by that. You might still have to monkey around with your water measurement. Other than that everything is pretty foolproof.
http://www.thesage.com/calcs/lyecalc2.php
Are you making sure to get your temperatures right, stirring until trace before pouring (a stick blender helps), and keeping the soap warm while it gels and sets overnight?
We made usable glycerine soap in chem. What kind has the class been trying to make?
Well, not being experienced in any way, I guess I didn’t realize the broad gap between oils and fats, and I started them off with Wesson corn oil. This should explain why they’re getting soft soap.
I think on Monday I need to turn them to shortening and the small jar of coconut oil I bought. Maybe that will improve things.
What does “stirring until trace” mean?
I have a thought; soapmaking calculators, such as the ones referred to above, refer to the dry weight of sodium hydroxide (lye), not the weight after it is dissolved in water. Please forgive me if you find this insulting, but you wouldn’t be the first potential soapmaker to make that mistake. Too little lye will definately give you a batch that doesn’t set up.
‘Trace’ means that when you lift you stirring implement from the soap and let it dribble back in, it doesn’t sink back into the mix immediately, but leaves a ‘trace’ on the surface. You’ll know it when you see it.
FWIW, I’ve made and sold cold-process soap for over 5 years.
“stirring to trace” means stirring or blending the fat/lye/water mixture until it reaches a pudding-like consistency, such that a line or trace of the mixture remains on top when you pull your utensil out of the mixture and dribble or pour what’s in the spoon on top of the mixture.
The descriptions of trace jibe with mine. You should be able to dribble little curlicues like on a Hostess cupcake. Also, you’re using sodium hydroxide, not potassium hydroxide as your lye, right? Sodium makes bar soap and potassium makes liquid soaps and shampoos. (So I’m told - I never got around to finding a good source for potassium hydroxide.)