Soap not lasting :(

[MOGal70]

A soured milk -- yogurt or buttermilk -- will increase the sodium lactate in soap...

DeeAnna do you mean any soured milk or just soured yogurt or buttermilk?

 

[MaitriBB]

I usually tell people who ask that the soap will last roughly one week per ounce with good drainage.

 

[Paintguru]

Yep. Card-carrying nerd. Guilty as charged.

A soured milk -- yogurt or buttermilk -- will increase the sodium lactate in soap, if you don't want to add sodium lactate directly as an ingredient.

Is there any reason/advantage to add sodium lactate vs. say sodium chloride?

 

[DeeAnna]

MOGal -- I've read about people who save milk that has "gone bad" for use in soap -- the stuff that smells bad and has chunks in it. My understanding about this milk is that it may be "bad" due to contamination with organisms other than the beneficial ones that "sour" milk into yogurt, buttermilk, etc. But some folks use it anyway. I personally prefer to use milk products in my soap that I would be willing to actually eat. YMMV.

edit: Milk soured with added vinegar or lemon juice doesn't have any lactic acid in it, which is what yogurt and buttermilk cultures create in milk. For soap, you want milk that is sour due to lactic acid.

Chris -- I don't know the answer to your question; maybe others can chime in. Some people do talk about using sodium chloride to harden their soap, but I don't have any nerdly specifics on that.

 

[Paintguru]

Chris -- I don't know the answer to your question; maybe others can chime in. Some people do talk about using sodium chloride to harden their soap, but I don't have any nerdly specifics on that.

Darn it . I was wondering if it was almost like a crystallization process, where if you seed nucleation sites into the solution (add salt), you get faster crystallization vs. the solution having to create its own nucleation sites from defects/contaminants within the system.

 

[DeeAnna]

Well, there are a couple of things I can suggest, Chris.

The old soapmakers would saponify with "potash" (KOH leached from ashes) in the days before NaOH was synthesized industrially. Then they would partially convert the soft KOH soap to a harder sodium soap by adding a brine of common salt and water to the soap and heating the mixture. Sodium ions are sodium ions regardless of whether they come from table salt or NaOH, so I'm speculating that adding salt to a modern soap recipe might have the effect of ensuring complete conversion of the fats to sodium soap.

Another thought -- Finished solid soap is a colloid of water in soap. It's a long story, but the addition of sodium chloride to a clay soil will cause the soil to become like concrete. Could sodium and chloride ions in the water phase of a soap alter and harden the soap structure in a similar way? Just speculation....

 

[heartsong]

adding sodium chloride (table salt) will depress bubbles...that's why most salt bars (spa bars) are made almost exclusively with coconut oil which is the only oil when saponified that will lather in salt water.