I just found out that I have some rancid old stuff in a box. I want to see if I can reuse it for something where that doesn’t matter so much.
I have this rancid stuff:
- 250 mL shea butter, bought 4 years ago
- 250 mL shea butter, bought 8 months ago
- 500 mL coconut oil, bought who knows how long ago
- “Jojoba oil” (mostly grape, then jojoba, some vit E and also sunflower), bought I don’t know how long ago
- 150 mL glycerine, bought I don’t know how long ago
I can’t find any uses for the rancid glycerol, I’ll probably just throw it out. I guess it could burn in a diesel stove or perhaps mixed with ethanol in a small burner, although it would produce a lot of particulates and I haven’t got any of those anyway.
The newer shea butter smells slightly vinegary, but the others are most definitely very rancid. I think it would be fun to see if I can reuse at least some of them for something.
One way to reuse rancid butter & oil for soap is to do a brine wash, to salt out the non-saponifiables. There’s a good guide in this thread. Nice video here.
I have an idea to make liquid dish soap from the shea butter and jojoba. Something like the liquid laundry detergent I also want to make, but with 10% soap added. For the soap I could use this calculator to see how much lye I need; since I don’t want superfat and I will brine wash anyway I think I can use an excess of lye.
- 10% soap
- 1.1% lye
- 8.9% shea butter
- 15% SLS
- 5% Coco betaine
- 3% Coco glucoside
- Citron essential oil
- pH adjustment to about 9
No idea if this recipe would actually work. It would cost about €2.50 per liter in ingredients which is slightly higher than store-bought washing up liquid. So.. I might as well just try to dissolve the soap in store bought washing up liquid?
Some more research: apparently this would make it a “combo” soap, although that might refer to anhydrous products. These products apparently contain 10-50% mild syndet (surfactant based soap) next to the regular soap. Syndet bars (e.g. shampoo bars) can be around 80% surfactant, so soap:surfactant ratio is roughly anywhere between 10:1 and 1:1.
On the other hand, traditional soap is known to leave film on dishes and on the sink, and regular washing up liquid works just fine, so there is no reason to actually do this other than to use something that I should throw away. Also, rancid oil can cause people to develop annoying sensitivity to specific oils.
Maybe I should just do that and throw all this stuff out.
Update 3 weeks later: I’ve discarded everything rancid in the “used oils” waste disposal bin. I’m proud of myself