Stearic, Palmitic and Lather

[Dean]

Does any amt of stearic or palmitic inhibit lather? Almond oil scores highest on a single oil soap test for lather but it makes for a very soft bar with a normal cure time. I find that at least 30% stearic + palmitic is required for hardness but then there r no bubbles. 25% and the bar is soft and still no bubbles.

 

[psfred]

Assuming you are making bath soap with only sodium hydroxide, yes, you can reduce lather with excess saturated fatty acids. The "ideal" soap has roughly equal amounts of saturated and unsaturated fatty acids. This shows up at some place in all soap calculators, in SoapCalc it's at the top of the recipe page as a ratio between the two fats.

For shaving soap with large amounts of KOH instead of NaOH, you want at least 50% palmitic plus stearic acids to produce dense, lasting shaving lather. Lower than 60% KOH you won't get decent lather.

My take on bath soaps is that I cannot tell the difference in lather over all the recipes I've tried other than that castiles don't lather well without a wash cloth for hand washing.