This site holds the best article I found concerning comparison of pH Test Strips Used for Testing Soap... http://www.millersoap.com/phtome.html , Hopefully I'll get permission to reprint it here.
Please pardon my speculation in what follows. I'm still in that part of the learning curve where I have to concentrate hard not to get my bases mixed up with my acids. Hey, base sounds like a LOW thing, does it not? And acid sounds so much more dangerous than a base. So why aren't bases lower numbers on the pH scale and Acids higher numbers? Just to goof me up, that's why. Anyhow, here's what I've learned about pH.
Bill M. at Cricket Hill (the chemist behind their bubble soap) suggests strongly that bubbling solutions have pH "sweet spots" ~ the pH where they will bubble best. Cricket Hill has a pH of 7 or 7.2 for example. That would be neutral.
10/25/05
Keeping in mind the more base something is the higher the ph and the lower the number the more acid it is. (Which I do need to keep in mind because things like draino are extremely base NOT acid even though it will still tear your skin apart.) Neither extreme is good. Base materials are generally high in alkalinity.
Mr. B is fairly neutral in 7.2 - 7.8 range. Gazillion was very low. Miracle Bubbles is into the 8+ numbers, Super Miracle bubs are even higher, Edible bubble solution is very low in the 6's or so, Fan Yang is near Mr. Bubs,
My variation of the solution on Sterling's site runs in the low to mid 8's, which is less base than just dawn complete & water, which is also more base than non-ultra Dawn. (Again higher numbers do a job on the skin of our hands.) Just glycerine is very low - acid. (At least that's what the colors show. Try as I might, I couldn't find the ph for glycerin/glycerol on the web or in msds.) And that may be the reason I like more glycerine in the solution because it helps to lower the higher base of the detergent. And why I believe the Dawn complete is gentler for my skin ~ because I add in so much glycerine which lowers ph. closer to neutral). I tested my solution and it came out base, like I said. The more glycerin I added the more neutral it became. (This just from a few initial tests.) I think this may be why the old Dawn needed less glycerin than the ultras and why you folks who grew up with the old Dawn resist the idea of adding in much more glycerine (as in just as much glycerin as detergent). It seems wrong to you because your initial tests with the more acidic old Dawn would have reacted badly to as much glycerine as I add.?.
...Interesting words about baking soda from arm & hammer: "As we mentioned, baking soda helps regulate pH keeping a substance neither too acidic (sour tasting), nor too alkaline. Think of pH as a see-saw, with acidic pH tilting one way, alkaline pH tilting the other way, and neutral pH when the see-saw is level. When ARM & HAMMER Baking Soda comes in contact with either an acidic or an alkaline substance, it's natural effect is to neutralize that extreme pH - tilting the see- saw back toward level. And beyond that, baking soda has the capability to resist further changes in the pH balance - keep the see-saw level--this is called buffering."...
Bill suggests using baking soda to increase/buffer the pH, when needed. Just 1/8 of a teaspoon to 1/2 gallon of mix to start.
I'd like to get more accurate test strips for readings with a more strict register of color changes to reflect smaller gaps in pH measure. It would give me more exact readings. That said, the pool test strips (which are plastic with paper dye squares attached) reflected the same color changes for these solutions even when I watered them down by as much as 100% and re tested. The readings were also equal to the ones I got with a liquid based pool test kit, where you have to get a vial of solution and drop in 5 drops of liquid dye and then compare to a color chart. Dilution of solutions to help neutralize the color of the dish soaps, didn't seem to matter much.
Now I just have to figure out what all of this means I suppose, and re do the tests to make sure I get the same results. And find better test strips...
12/05
I also have read that some detergents (surfactants) have their surface tension altered by changes in PH. One more reason to test as you go along.