pH Testing on various soaps

[McSpin]

McSpin -- Have you split a bar and tested the center? My experience shows the exterior may be fine after a relatively short time, but the proof of full cure for a lye-heavy soap is when the center is fine too.

All of my pH tests have been take from the center of a fresh cut.

And, no, some soaps do remain lye heavy more or less indefinitely. One soaper in the 2014 "superlye" castile experiment made the lye-heavy soap but used a "normal" amount of water. The bars are still lye heavy in the interior according to recent comments she's made.

I don't doubt that different formulation will react with lye slower or faster, which is why I agree that pH testing is useful only if you are dealing with a soap you've made and tested before. When I first started this, I was expecting pH to be very informative. I am now beginning to believe that experience with how it should look and feel will prove to be the most obvious signs of a possible problem. If I'm using a 38% water ratio and someone else is using a 32% portion of water, what I observe from my soaps will not necessarily happen to the other. It really is a process of learning what to expect from your own formulas. I'm glad I decided to do this. I'm learning quite a bit about the curing process that I did not pick up from my previous batches.

 

[MorpheusPA]

Morpheus -- Your comparison doesn't apply -- we're not dealing with water; we're dealing with soap. Apples and oranges. Soap chemistry is closer to protein chemistry, not water.

Dunn wrote his book for freshman chemistry students and handcrafted soap makers. He knows this audience cannot work to the level of accuracy and precision typical of an industry or research lab, so his data is presented accordingly. Parts per thousand is decent accuracy for kitchen chemistry.

Lastly ... it works. You can speculate and theorize and criticize all you want, but real-life experience says otherwise.

I have to say I don't appreciate the tone here, but hopefully I'm reading you wrong.

The point being that 1 part per thousand simply isn't going to happen with sodium hydroxide. It's too reactive and the soap isn't like shielding pure sodium with mineral oil. The free fats react, and the water in which the NaOH is dissolved will transport it around as well as moving around dissolved CO2 over time.