Rosin
INCI Colophonium. Also: Colophony, Colophonium, Gum rosin, Wood rosin, Pine rosin, WW rosin, Water-white rosin, Resin.
Published values
| Saponification value | ≥ 160 mg KOH/g |
| Used by the calculator | 160.0 mg KOH/g (midpoint) |
| SAP for NaOH | 0.1141 g/g |
| Iodine value | — |
| INS (SAP − IV) | — |
| Melting point | — |
| Unsaponifiable matter | ≤ 6 % |
A bar made of 100 % Rosin
Conventional qualities summed from the fatty-acid groups; a single-oil bar is a reference point, not a recipe.
Fatty-acid profile
| Fatty acid | Published range, % | Used | |
|---|---|---|---|
| No fatty-acid profile could be sourced cleanly for this record yet. | |||
Where these numbers come from
Read from the Public.Resource.Org mirror of the Bureau of Indian Standards text. Table 1 gives, per type (extra pale / pale / medium / dark): softening point 70 C min for all; relative density 27/27 C 1.05–1.08, 1.052–1.082, 1.052–1.102; acid number min 160, 155, 155; saponification number min 165, 160, 160; volatile matter max 1.50, 2.0, 2.0 %; ash max 0.05, 0.2, 0.5 %; matter insoluble in toluene max 0.10, 0.40, 1.00 %; unsaponifiable matter max 6.0 % for all. Section 3.2 places the 15 colour grades under those four types, with WW at Gardner colour value 7 under "Pale" — so the pale-type figures are the ones used. Every requirement in the table is a minimum or a maximum; none is a range around a typical value, and the standard prints no typical values.
Rosin is not a fat. It is what is left after turpentine is distilled off pine oleoresin, and it is roughly nine parts resin acids — abietic and its isomers, C20H30O2 — which are single-carboxyl FREE acids. They neutralise lye directly, one hydroxide per molecule, with no ester to hydrolyse first. That is why IS 553's acid number (155 min for the pale types) and its saponification number (160 min) are almost the same figure, where a triglyceride's acid number is near zero and its saponification number near 200. So rosin soap is a real soap, sodium abietate, and it is what the 19th-century books mean by yellow soap. Six of the transcribed Thomssen and Watt recipes call for it by weight alongside the fats. It lathers freely, it is tacky and soft on its own, and the books keep it under about a quarter of the charge. What this record gives the calculator is a FLOOR, not a value. IS 553 specifies saponification number as a minimum per type — 165 for extra pale, 160 for pale and medium and dark — and sets no ceiling, because a standard's job is to say what a buyer is entitled to. WW is a pale-type grade (Gardner colour 7), so 160 is the figure here. For scale at the other end: pure abietic acid is C20H30O2, molar mass 302.45, one carboxyl, so 56106 ÷ 302.45 = 185.5 mg KOH/g, and a rosin that was entirely resin acid could not exceed that. A real WW grade sits between the two, and this record uses the floor, which under-doses the lye slightly and leaves the surplus as superfat. That is the safe direction to be wrong in. No fatty-acid profile is given because rosin has none — resin acids are diterpenes and none of them is in this schema's key list. That means the calculator can work out rosin's lye but not its contribution to hardness, cleansing or conditioning, and a blend containing it will report those qualities over the fats alone. The standard's other requirements, for reference: softening point 70 C min (a softening point, not a melting point, which is why the melting-point field is null), relative density 1.052–1.082 at 27/27 C for the pale type, volatile matter 2.0 % max, ash 0.2 % max, matter insoluble in toluene 0.40 % max.
This record is part of the open ingredient database (ODbL). Found an error or a better primary source? The dataset is on GitHub; corrections with a document link are welcome.