re-visiting the PH meter issue

[IrishLass]

In his Scientific Soapmaking book, Dr. Dunn recommends testing the different sides of your soap.


IrishLass

 

[wetshavingproducts]

And if this is the case (and I have seen it happen), then even a pH meter with a probe is still only going to test the pH of a particular spot where it touches. I am not defending pH meters, per se, because a specific pH does not equal lye, just pointing out that all tests are only going to give the results of the area tested. That's just the way it is regardless of what you test and how what method you use, be it soap or dirt or any other solid. It would of course be somewhat more reliable with liquid soap, I expect because it is already in solution and one would expect a fair uniformity of said solution.

AFAIK, a PH meter requires an aqueous solution to even work or at least to give an accurate reading. So, IIRC, you take a piece of bar soap, dilute it with distilled water, and then take a reading from that.

In other words, it only tests the PH of the chunk of soap you cut off.

But then again, most tests are really spot tests, so... act accordingly I guess.

 

[psfred]

The definition of pH is the negative logarithm of the hydrogen ion concentration in water -- sans water, there can be no pH value!

pH in soapmaking is a tool, but not particularly useful for most of us. You can use a pH meter to titrate the alkalinity of soap, but phenolthalein is easier and cheaper (and you still have to dissolve the soap in water).

 

[Nite Hawk]

I have been away for a while, so am just now going over the last posts..
It appears that soap cures from the outside inwards, due to having broke a bar in half and having a different results from the inside to the exterior.
So just testing the outside of the bar , no matter what the method used -- it appears that soap makers could be having a false sense of security of the condition of cure- due to the variation of the condition of the soap from the inside to the outside. I realize most people use the outside of a soap bar first- (LOL)-that is real normal-- leaving time for the inside to continue curing while the outside in being used.
However I often break a soap bar in half if I run out of soap in one of the rooms-the kitchen or bath room- using the other half in another place in the house, therefor exposing a possible uncured section to the skin in use.
That is one of the reasons I wondered if there were any new ways to test soap, and that a PH probe, might give a general indication of the condition of the inside of the bar.
As for "hot spots" of lye inside of a bar, is the reason for that, that it might possibly have not been mixed fully, or the lye completely dissolved from its pellet form??
I use a stick blender, and it seems to blend things pretty well.
Any thoughts?