Ph testing for soap

Soapmaking Forum

Help Support Soapmaking Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Tinak

Member
Joined
Jun 21, 2018
Messages
12
Reaction score
4
Location
Oregon
Okay I have a question I hope this is okay to ask... what is the best pH tester for checking your soaps pH level? There are lots out there and I don't really have a lot of $ to invest but I'd like a good reliable way to test ....
 
You really don’t need to test the PH. Strips are inaccurate for bar soap. Zap testing is really all you need.
I am making cold process shampoo bars by customer request and I'd really like the ph to be in the correct range for hair care
 
Testing the pH of lye-based soap is a tricky endeavor because the surfactant nature of soap messes with the chemicals used on pH strips, especially the paper-type of strips (see here ). We all here can tell you stories of false readings from paper strips used on our soaps, for example giving us neutral readings of 7, which is an impossible pH to get from a lye-based soap. It's impossible because lye-based soap by definition is an alkaline salt of fatty acids. A 'normal' pH reading for lye-based soap can range anywhere from 8.5 to even as high as 12-something and be perfectly safe (i.e., not lye-heavy).

The best, most simple, least expensive way to test for lye-heaviness is the tongue test, as Shari mentioned above.

Having said all that, the best strips to use (if you want to go the strip route) are the plastic, lab-grade type mentioned in the link I provided in my first paragraph.


IrishLass :)
 
I am making cold process shampoo bars by customer request and I'd really like the ph to be in the correct range for hair care

If what you're talking about is a pH of neutral (7) to acidic (below 7), then lye-based soap will never "be in the correct range."

Soap always has a pH from about 9 to about 11. If you force the pH of soap below this normal range by adding acid, soap will no longer be soap -- it breaks down into fatty acids.

If you need a lower pH product, you will need to use synthetic detergents which can have a pH of 7 or less.
 
Bottom line Tinak, is everyone, myself included, is offering you free advice; and it’s worth every penny you pay for it. [emoji6] The Modern Soaping article linked above is a great research and learning piece; however, it’s a perfect example of “Your mileage may vary”. I work in the lab of a compounding pharmacy and use the more accurate ‘big brother’ of the digital meter she used in her article. I run QC tests on our meter using a set of 3 fluid standards. I’ve tested my own soap using the testing standards utilized in the article using our meter. I also got the same result on my test strips. As stated several times by several folks, I use testing to ensure a consistent product and to avoid defending the liability of only a ‘Zap’ test. Happy soaping!
 
If you are going to worry about ph in a soap bar being used for shampoo do not bother, since it will never be a safe ph for hair. You can use all the ph meters you want and will not accomplish it.

Would be interesting to know how Backdraft controls the ph of soap since different oil combinations can affect the ph of soap. If if does not zap I use it and sell it, and yes I have had a couple zappy soaps in my soapmaking career. Once happened to be a recipe from a well known soapmaker and teacher which I was never able to get zap free. Never knew what went wrong
 
Last edited:

Latest posts

Back
Top