Cold Process Soap Info

Just dumping some bits of info.

Lye (NaOH) solution must be stored in HDPE (High-density polyethylene, recycling code 2) or PP (Polypropylene, recycling code 5). It'll etch glass, you don't want glass particles in your soap.

I've seen people claim clay helps retain scent, and others refute this. I wonder if anyone's done experiments testing this.

Vanillin will discolour soap and turn it brown. Unsure how even and reproducable the effect is, and over which timespans it will change the colour.