A working journal about cold process soap: saponification, cure times, superfatting, oils and the craft of making a bar that is actually worth using.https://therasatheory.com/enhttps://therasatheory.com/blog/activated-charcoal-in-soap/https://therasatheory.com/blog/activated-charcoal-in-soap/Charcoal soap is sold as a detox. The real story is smaller and more useful: what activated charcoal does in a rinse-off bar, and which claims to ignore.Sun, 04 Oct 2026 00:00:00 GMTingredientscharcoalbuying soaphttps://therasatheory.com/blog/cosmetic-clays-compared/https://therasatheory.com/blog/cosmetic-clays-compared/Cosmetic clays differ mainly in how much oil and water they absorb. Here is how the common ones compare, which is gentlest, and which suits which skin.Sun, 04 Oct 2026 00:00:00 GMTingredientsclaysensitive skinhttps://therasatheory.com/blog/how-to-make-soap-last-longer/https://therasatheory.com/blog/how-to-make-soap-last-longer/Most bars do not wear out, they dissolve. Six habits that slow that down, from the soap dish to the cure, and why a handmade bar rewards them more than most.Sun, 04 Oct 2026 00:00:00 GMTusing soapbuying soaphttps://therasatheory.com/blog/manjistha-in-soap/https://therasatheory.com/blog/manjistha-in-soap/Manjistha is Rubia cordifolia, the Indian madder root that dyes a soap rose to red-brown. Where it comes from, what it does in a bar, and what is only tradition.Sun, 04 Oct 2026 00:00:00 GMTingredientsmanjisthaindian botanicalsnatural colourhttps://therasatheory.com/blog/tangedu-tanners-cassia/https://therasatheory.com/blog/tangedu-tanners-cassia/Tangedu is Senna auriculata, the state flower of Telangana and a fixture of Bathukamma. What the plant is, where its name comes from, and what we can honestly claim.Sun, 04 Oct 2026 00:00:00 GMTingredientstangeduindian botanicalshttps://therasatheory.com/blog/why-handmade-soap-costs-more/https://therasatheory.com/blog/why-handmade-soap-costs-more/A handmade bar can cost several times a supermarket one. Where that money goes: the oils, the weeks on a curing rack, the glycerine, and the work done by hand.Sun, 04 Oct 2026 00:00:00 GMTbuying soapcold processhttps://therasatheory.com/blog/why-real-soap-is-alkaline/https://therasatheory.com/blog/why-real-soap-is-alkaline/True soap always tests alkaline, usually between pH 8 and 11. Here is why that follows from the chemistry, and what a bar sold as pH 5.5 actually contains.Sun, 04 Oct 2026 00:00:00 GMTchemistryphbuying soaphttps://therasatheory.com/blog/how-to-read-a-soap-label/https://therasatheory.com/blog/how-to-read-a-soap-label/Saponified oils, INCI names, syndet bars and the word natural. A practical guide to telling real cold process soap from a decorated commercial base.Fri, 14 Aug 2026 00:00:00 GMTlabelsbuying soapcold processhttps://therasatheory.com/blog/superfat-and-lye-discount-explained/https://therasatheory.com/blog/superfat-and-lye-discount-explained/Superfat and lye discount are the same adjustment described from opposite ends. Here is the arithmetic, worked in full, and how to pick a number.Wed, 29 Jul 2026 00:00:00 GMTsuperfatformulationchemistryhttps://therasatheory.com/blog/how-long-soap-needs-to-cure/https://therasatheory.com/blog/how-long-soap-needs-to-cure/Cure times by recipe type, what is actually happening during the cure, and which of the numbers everyone repeats are measured rather than inherited.Wed, 08 Jul 2026 00:00:00 GMTcuringcold processchemistryhttps://therasatheory.com/blog/what-is-saponification/https://therasatheory.com/blog/what-is-saponification/Saponification is the reaction that turns fat and lye into soap and glycerine. Here is what happens molecule by molecule, and why no lye survives it.Wed, 24 Jun 2026 00:00:00 GMTsaponificationchemistrylye safetyhttps://therasatheory.com/blog/cold-process-vs-melt-and-pour-vs-hot-process/https://therasatheory.com/blog/cold-process-vs-melt-and-pour-vs-hot-process/The three common ways to make soap differ in chemistry, control and cure time. Here is what genuinely separates them, and which one suits what you want.Wed, 10 Jun 2026 00:00:00 GMTcold processmethodssaponification