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Household bars

Curd soap, typical charge

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The oils

Oil As the source prints it Share
Oleic Acid Red oil · 63 parts 63.0 %
Edible Tallow (beef/mutton dripping) Tallow · 10 parts 10.0 %
Rosin 27 parts 27.0 %

How it is made

Process Full-boiled
Alkali Not stated
Superfat Not stated
Water as the source states it
Iodine value 84
INS 113

This is a boiled soap. A kettle soap has its excess alkali salted out and drawn off before framing, so the recipe states the alkali charged, never the alkali the bar keeps. Read as a modern cold-process recipe it would be lye-heavy.

What the numbers say

Hardness 7 below 29–54
Cleansing 0 below 12–22
Conditioning 60 44–69
Bubbly lather 0 below 14–46
Creamy lather 6 below 16–48

Computed from the fatty acids of the fats above. The bands are what the craft has settled on, not chemistry — a bar outside one is not wrong.

The source

Grained rather than settled, to get a hard bar out of low-titre fat. 27 % rosin is the highest in the book.

E. G. Thomssen, Soap-Making Manual: A Practical Handbook on the Raw Materials, Their Manipulation, Analysis and Control in the Modern Soap Plant, D. Van Nostrand Company, 1922, p.72. Soap-Making Manual: A Practical Handbook on the Raw Materials, Their Manipulation, Analysis and Control in the Modern Soap Plant · read 2026-09-22

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