Historical soap · calculated safely
Saponaria pairs old recipes with the arithmetic they never had: a precise saponification calculator, a free field-guide ebook, and a Pro vault for serious makers — paid in Bitcoin over Lightning.
Free tool
Pick your oils and weights, set a superfat, and get the exact NaOH or KOH and water — with lye-safety guidance built in.
Calculate a batch →Free download
A field guide to historical soap: a short history, the science of saponification, and how to handle lye — including the wood-ash tradition — safely.
Read the ebook →Saponaria Pro
Save unlimited recipes to your account, unlock the advanced calculator (cost-per-bar, fragrance load, water:lye), and open the premium recipe vault. Bitcoin Lightning only — no cards, no subscriptions you forget to cancel.