In this post, Weekend Wonderings: Have a question?, Valerie asked: Are there guidelines on to dilute (with distilled water) a sample of a product before testing to get ph test accurate results - like shampoo, lotion etc. I have pH tested my liquid soaps in the past and was instructed to dilute appropriately before testing to get accurate results. Any advice is appreciated! I have made a powdered foaming exfoliating cleanser that I would like to pH test. I have a digital reader and a know how to calibrate it using the solutions. Also, I would love to post this recipe for feedback and suggestions on how to improve it.
If you're using distilled water - which should have a pH of 7 or neutral - then the only change to the water is the thing you want to measure. So using as little as 1% should be enough to alter the pH enough to be measured. I generally use 10% as I usually have my 1 gram scale handy versus my tinier scale, so I use 10 grams product to 90 grams distilled water.
Why do we have to dilute our products? It's obvious in the case of a shampoo bar or solid soap, but this is important for anything that's thicker than water as the electrodes aren't equipped to measure pH in viscous materials, like lotions. It won't give you an accurate measurement if you just dip it into the lotion or shampoo. Dilute it and you're good!
How to calibrate your machine? You'll have to read the specifics from the manual, but the ones I've used suggest we should have liquids for pH 4 and 7 and, if possible, 10. I push the button, and place it in the pH 7 liquid until it notes it's done there, hit save, then put it in the pH 4 liquid, and do the same thing. It's calibrated!
Where do I get my calibration fluids? I get mine from either Lotioncrafter or at my local hydroponics store.
Those of you who have been here for a while may have noticed that I'm using a different pH meter. My old one, a Jenco Vision Plus 630, which I loved so much, needed a new electrode, and I couldn't figure out where to buy it. I bought a new one from Amazon last month - Hydrofarm HM Digital HMDPH200 Waterproof PH and Temperature Meter - and I'm really happy with it so far. (Not an affiliate link, just sharing information.)
Let's take a look at what pH means!
pH of our skin's acid mantle
pH of our bodies
pH OF OUR PRODUCTS
What pH should lotions be?
Another look at the pH of our lotions
pH of shampoo
pH of conditioners
Adjusting pH of our products
An example of me adjusting pH in our products
Calibrating my pH meter
What pH meters are good?
Equipment for measuring pH