soapformulator
EN

2 of 40 historical soaps fit today’s soap quality numbers

Most lye calculators print the same seven numbers for a recipe, with a recommended range beside each: hardness, cleansing, conditioning, bubbly and creamy lather, iodine value and INS. We put the 40 formulas we can compute from two soap-trade books, Alexander Watt’s The Art of Soap-Making (1884) and E. G. Thomssen’s Soap-Making Manual (1922), through the same numbers. Two of them fall inside all seven ranges.

What the numbers say

The 2 inside every range: Thomssen’s olive, tallow and cocoanut base (1922) and Thomssen’s palm and olive base (1922). Both are factory toilet-soap bases, blends of olive oil, tallow or palm oil with a fifth of coconut oil, not far from a modern cold-process bar. Of the 27 bars in the set, household and toilet soaps, 2 fit.

Marseilles soap, Watt’s formula of olive oil alone, scores hardness 17 against a range of 29 to 54, and cleansing 0 against 12 to 22. By the table, one of the best-known soaps there is comes out too soft and does not clean. An olive soap hardens over a long cure, which the numbers cannot see: the castile guide goes through it.

Windsor soap, nine parts tallow to one of olive oil and the most famous named soap in Watt’s book, misses cleansing and bubbly lather: cleansing 4, where the range starts at 12. A tallow soap lathers from its palmitic and stearic acids, which the convention counts as creamy lather, not as cleansing.

The coconut soaps miss the other way. Thomssen’s cold-made cocoanut oil soap scores hardness 80 and cleansing 68, far above both ranges, as a soap made for heavy cleaning would.

The range most formulas miss is conditioning (29 of 40: 24 below it, 5 above).

Why so few fit

The ranges are a convention of hobby lye calculators, in use since about 2005, written for a hand-made cold-process bar with a superfat and a cure. The five qualities are sums of fatty acids: hardness is lauric, myristic, palmitic and stearic acid together, cleansing is lauric and myristic, and so on. They are not measurements of a bar. They ignore the superfat, the water, the cure and anything added, and they count every acid in a group as the same. The formulas on the formulas page are the calculator’s, with their sources.

Most of these formulas were not that kind of soap. A boiled soap was salted out and washed on the kettle, which takes much of its glycerin and spare lye away; the numbers read only the fats that went in. The shaving creams, the liquid and transparent soaps and the scouring soaps were never meant to be hard bars. None of that makes the ranges wrong for what they were written for. It shows what they are: a guide to one modern way of making soap, not a measure of what soap can be.

Every formula

Sorted by how many ranges each misses. A figure outside its range is marked ↓ below or ↑ above. The values are the calculator’s, rounded as it rounds them.

Formula Book Made as Hardness 29–54Cleansing 12–22Conditioning 44–69Bubbly 14–46Creamy 16–48Iodine 41–70INS 136–165 Misses
Olive, tallow and cocoanut base Thomssen 1922, p. 68 · toilet bar Thomssen 1922, p. 68 toilet bar 43 15 52 15 28 54 152 0
Palm and olive base Thomssen 1922, p. 68 · toilet bar Thomssen 1922, p. 68 toilet bar 46 14 52 14 31 53 155 0
Toilet soap fat group I (tallow and colza) Watt 1884, p. 135 · toilet bar Watt 1884, p. 135 toilet bar 53 20 36 ↓ 20 34 44 165 1
Olive oil base (white), leanest of the stated range Thomssen 1922, p. 67 · toilet bar Thomssen 1922, p. 67 toilet bar 32 17 64 17 15 ↓ 65 141 1
Palm, olive, tallow and cocoanut base Thomssen 1922, p. 68 · toilet bar Thomssen 1922, p. 68 toilet bar 53 16 41 ↓ 16 37 44 164 1
French formula IV — white soap with cocoa-nut Watt 1884, p. 50 · household bar Watt 1884, p. 50 household bar 41 9 ↓ 55 9 ↓ 32 58 143 2
Lard soap, cold process Watt 1884, p. 83 · toilet bar Watt 1884, p. 83 toilet bar 42 2 ↓ 55 2 ↓ 40 60 138 2
Windsor soap Watt 1884, p. 150 · toilet bar Watt 1884, p. 150 toilet bar 48 4 ↓ 46 4 ↓ 44 50 145 2
Palm kernel and red oil charge Thomssen 1922, p. 101 · textile scouring Thomssen 1922, p. 101 textile scouring 25 ↓ 20 67 20 5 ↓ 68 143 2
Tallow, palm and cocoanut base Thomssen 1922, p. 67 · toilet bar Thomssen 1922, p. 67 toilet bar 53 9 ↓ 44 9 ↓ 44 46 158 2
French formula II — hard palm and sesame soap Watt 1884, p. 49 · household bar Watt 1884, p. 49 household bar 43 1 ↓ 56 1 ↓ 42 63 134 ↓ 3
French formula III — tallow-led soap Watt 1884, p. 49 · household bar Watt 1884, p. 49 household bar 37 2 ↓ 58 2 ↓ 34 63 131 ↓ 3
Tallow soap by Hawes's cold process Watt 1884, p. 80 · household bar Watt 1884, p. 80 household bar 52 4 ↓ 43 ↓ 4 ↓ 48 47 150 3
Cold-made transparent soap IV Thomssen 1922, p. 87 · transparent Thomssen 1922, p. 87 transparent 48 26 ↑ 40 ↓ 45 41 41 174 ↑ 3
Palm base (leanest of the stated range) Thomssen 1922, p. 67 · toilet bar Thomssen 1922, p. 67 toilet bar 57 ↑ 18 40 ↓ 18 39 41 172 ↑ 3
Palm base (richest of the stated range) Thomssen 1922, p. 67 · toilet bar Thomssen 1922, p. 67 toilet bar 56 ↑ 15 42 ↓ 15 41 44 167 ↑ 3
Palm kernel and corn oil charge Thomssen 1922, p. 101 · textile scouring Thomssen 1922, p. 101 textile scouring 52 40 ↑ 43 ↓ 40 12 ↓ 58 165 3
Tallow base (richest of the stated range) Thomssen 1922, p. 67 · toilet bar Thomssen 1922, p. 67 toilet bar 54 10 ↓ 39 ↓ 10 ↓ 44 43 159 3
Tallow base, kettle charge Thomssen 1922, p. 36 · toilet bar Thomssen 1922, p. 36 toilet bar 53 10 ↓ 38 ↓ 10 ↓ 43 43 160 3
Toilet soap fat group III (tallow and palm) Watt 1884, p. 135 · toilet bar Watt 1884, p. 135 toilet bar 58 ↑ 19 38 ↓ 19 39 40 ↓ 173 ↑ 4
White soap, cold process, small batch Watt 1884, p. 82 · toilet bar Watt 1884, p. 82 toilet bar 59 ↑ 20 34 ↓ 20 39 37 ↓ 174 ↑ 4
Tallow base (leanest of the stated range) Thomssen 1922, p. 67 · toilet bar Thomssen 1922, p. 67 toilet bar 59 ↑ 20 34 ↓ 20 39 37 ↓ 174 ↑ 4
Yellow soap with cocoa-oil Watt 1884, p. 75 · household bar Watt 1884, p. 75 household bar 60 ↑ 34 ↑ 24 ↓ 34 25 27 ↓ 203 ↑ 5
Cold-made transparent soap I Thomssen 1922, p. 86 · transparent Thomssen 1922, p. 86 transparent 56 ↑ 26 ↑ 34 ↓ 33 37 36 ↓ 181 ↑ 5
Cold-made transparent soap V Thomssen 1922, p. 87 · transparent Thomssen 1922, p. 87 transparent 63 ↑ 29 ↑ 29 ↓ 29 33 31 ↓ 189 ↑ 5
Shaving cream II Thomssen 1922, p. 91 · shaving Thomssen 1922, p. 91 shaving 97 ↑ 15 3 ↓ 15 82 ↑ 2 ↓ 216 ↑ 5
French formula I — white, odourless soap Watt 1884, p. 49 · household bar Watt 1884, p. 49 household bar 25 ↓ 1 ↓ 71 ↑ 1 ↓ 25 77 ↑ 117 ↓ 6
Marseilles soap Watt 1884, p. 37 · household bar Watt 1884, p. 37 household bar 17 ↓ 0 ↓ 82 ↑ 0 ↓ 17 85 ↑ 106 ↓ 6
Cold-made transparent soap III Thomssen 1922, p. 86 · transparent Thomssen 1922, p. 86 transparent 59 ↑ 37 ↑ 34 ↓ 51 ↑ 36 33 ↓ 192 ↑ 6
Curd soap, typical charge Thomssen 1922, p. 72 · household bar Thomssen 1922, p. 72 household bar 7 ↓ 0 ↓ 60 0 ↓ 6 ↓ 84 ↑ 113 ↓ 6
Olive oil base (white), richest of the stated range Thomssen 1922, p. 67 · toilet bar Thomssen 1922, p. 67 toilet bar 23 ↓ 7 ↓ 75 ↑ 7 ↓ 16 77 ↑ 120 ↓ 6
Oleic acid (red oil) soap Watt 1884, p. 83 · household bar Watt 1884, p. 83 household bar 3 ↓ 0 ↓ 88 ↑ 0 ↓ 3 ↓ 90 ↑ 107 ↓ 7
White cocoa-oil soap (Sturtevant's process) Watt 1884, p. 74 · household bar Watt 1884, p. 74 household bar 75 ↑ 63 ↑ 15 ↓ 63 ↑ 12 ↓ 14 ↓ 237 ↑ 7
Cold-made cocoanut oil soap Thomssen 1922, p. 43 · household bar Thomssen 1922, p. 43 household bar 80 ↑ 68 ↑ 9 ↓ 68 ↑ 12 ↓ 8 ↓ 248 ↑ 7
Liquid soap I (cocoanut) Thomssen 1922, p. 95 · liquid Thomssen 1922, p. 95 liquid 80 ↑ 68 ↑ 9 ↓ 68 ↑ 12 ↓ 8 ↓ 248 ↑ 7
Liquid soap II (corn oil) Thomssen 1922, p. 95 · liquid Thomssen 1922, p. 95 liquid 15 ↓ 0 ↓ 82 ↑ 0 ↓ 14 ↓ 119 ↑ 72 ↓ 7
Liquid soap III (dilute cocoanut) Thomssen 1922, p. 95 · liquid Thomssen 1922, p. 95 liquid 80 ↑ 68 ↑ 9 ↓ 68 ↑ 12 ↓ 8 ↓ 248 ↑ 7
Pumice soap I Thomssen 1922, p. 93 · scouring Thomssen 1922, p. 93 scouring 76 ↑ 66 ↑ 18 ↓ 66 ↑ 10 ↓ 18 ↓ 227 ↑ 7
Sand soap II Thomssen 1922, p. 93 · scouring Thomssen 1922, p. 93 scouring 80 ↑ 68 ↑ 9 ↓ 68 ↑ 12 ↓ 8 ↓ 248 ↑ 7
Shaving cream I Thomssen 1922, p. 91 · shaving Thomssen 1922, p. 91 shaving 98 ↑ 11 ↓ 3 ↓ 11 ↓ 87 ↑ 2 ↓ 214 ↑ 7

How this was worked out

Each formula’s fats are taken by mass as the book printed them, in parts, pounds or percent, and each fat’s fatty acids from the site’s oil database, where every figure names its primary source. The seven numbers are the lye calculator’s own, from the same code, and a figure counts as inside its range when its rounded value is, as the calculator shows it. The formulas themselves are on the historical formulas page, each with its book and page, and can be downloaded as CSV or JSON.

11 of the 51 formulas are left out, because a fat in them is not one the database carries: Talgol Extra; Cottonseed foots or its equivalent in fatty acids; House Grease; Distilled grease; Cotton oil foots stock, 63% fatty acid; Olive Oil Foots; Talgol; Bone Grease; Tallow-oil. A blend worked out from four of its five fats would not be that formula’s blend.

Read more: fatty acids and soap qualities, where the ranges came from and when to ignore them, and iodine value and INS.