Saponify with something like a 60 / 40 ratio of Potassium Hydroxide to Sodium Hydroxide (or even 66 / 33). Note that this ratio division is calculated in terms of the saponification value - not weight.
Try to get the purest KOH you can find. I've found some vendors selling KOH which is only around 90% pure which is low enough to start to muck up your calculations (and increases the chances of DOS). The purest KOH I've found has come from companies supplying those making D.I.Y biodiesel.
The soap will be a softer but the sodium hydroxide will give it enough body for it to form a hard bar. The resulting potassium stearate is much more soluble in water than sodium stearate which means the properties of the stearic acid (principally a very dense creamy lather) can be fully utilised.
A bias towards potassium hydroxide over sodium hydroxide is common practice in commercial shaving soap making and this is why the potassium salts are often listed before the sodium salts in the ingredient list. One commercial shaving soap I know of that didn't do this was the (old) reformulated Erasmic shaving stick. It contains no potassium salts at all and is regarded one of the most useless commercially-made shaving soaps of all time.
Last edited by Fortitudo Dei; 03-24-2011 at 01:03 AM.
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