Why test pH?
For the most part, skincare isn't really pH dependent. Most creams, toners, and serums tend to hang around the 5.5 mark, just...because. They also don't usually have ingredients that need to be in a certain range to be happy. But some products do. And those that do really need them to be within a small window. Acids, for example, won't exfoliate if they're not in an acidic enough environment. Vitamin C, for example, needs a very specific pH range or it's just useless.
And then there are cleansers. Read these posts by Kerry (Skin & Tonics) and Cat (Snow White & the Asian Pear) on the importance of a mildly acidic cleanser to have your mind blown. My take on it? I live the low pH life, baby.
|We ride low on the pH scale.|
A quick note: Just because a cleanser comes out to 5.5 pH does NOT make it automatically a good cleanser. It is just the bare minimum it has to meet before I'm willing to actually try it. After that, other things go into consideration, like if it's drying, if it burns my eyes/face, if it leaves a filmy residue, and many other things. But it must hit that sweet pH spot first, or it's just not going to get used.
What do you need?
|From Amazon.com, but I'm not linking them. Because they're made of butts and lies.|
You're going to need pH strips. That rainbow above? They're technically pH strips, but don't buy that crap.
|From Amazon.com, $7.95 w/ Prime|
I have these, and they're quite affordable at $7.95 (as of 10/4/15) with Prime shipping for 100 strips. See how they have 4 squares on each strip? This provides a more accurate reading. It's not foolproof, and you won't be able to look at it and go, "Oh, that's a pH of 3.86," but it'll be enough. You don't have to get this specific brand, but it's the cheapest of the ones I own (yes, I own more than one set...I actually have 3...my excuse is I DIY.) You can also use a pH meter if you wanna get all fancy with it, just keep in mind that at least with some pH meters, you canNOT immerse them in any sort of lipids/oils/fats whereas pH strips are single use disposable things that honestly couldn't care where they're going.
And then you need what you're testing, obviously. Ready?
How to test pH
CleansersHow is this cleanser when it goes on your face? Does it go straight from bottle to skin, or does it need to be worked over a bit in your hands to get nice and frothy? The idea is to replicate the condition it is in when it's on your face. So you don't need distilled water, you don't need fancy equipment, you don't even need measurements.
I start oil cleansing with dry hands and a dry face. I then emulsify and wash everything off with tap water and, while my hands are still wet, start on my foaming wash, which I lather up a bit with my hands before I spread it around on my face. So when I'm testing pH, I do the same thing and instead of slapping it on my face, I stick a pH strip over it.
Couldn't that affect the pH?
Yep. Does it matter? Nope. Sure, a cleanser could read differently if it was fully concentrated right out of the container, or barely diluted, or using distilled/fancy water or whatnot...but that's not how it's going on your face, and that is ultimately all that matters. What the pH is when it's mixed by pH trained laboratorians using one aliquot of fresh, activated charcoal filtered, virginal Jeju Island spring water doesn't mean a damn thing unless that's what you'll be using to wash your face in every day.
This doesn't require much. Simply pour a small amount into the palm of your dry hand, and dip the pH strip onto it, making sure to saturate all the squares. Or if you have good aim, you can try to dribble straight onto the pH strip. I like the palm method, because any excess just goes straight onto my face. Why dry hand? Again, we're simulating the conditions of when you're applying it to your face. When you have drippy wet hands and you apply your acids, you are diluting them, possibly to an ineffective level. So after I've rinsed my face, I pat my hands dry before proceeding, and same for when I'm testing pH.
Unfortunately, that varies depending on what you're testing. For AHAs, you generally want between 3-4, BHAs around 3-3.5, L-Ascorbic Acid between 2.5-3.5, and...well, the list goes on.
Testing Other Products?
I like to test pH of mud masks. Because clay is naturally alkaline, and who knows if a company bothered to pH adjust. But clay is also, by nature, um...not clear. So how do we test with some paper strips and actually read the results? An experiment:
This was a Snapchat from last night when I was testing calcium bentonite (super alkaline) with apple cider vinegar (super acidic) for a mud mask base that I'm working on. As you can see, it's...quite paste-y and thick. I did two tests: On one, I smeared it straight onto the pH stick, waited a moment, and then rinsed it off, taking care not to damage the paper (some strips, the pH paper will come right off), and then compared it to my table. On another, I took a similar amount, diluted it down (significantly) with some regular water, and then pH tested. There's a notable difference, with one being around a pH of 5.5-6.5ish, and another being closer to 6.5-7.5ish. That doesn't sound like much, until you remember that pH is a logarithmic scale, so a pH of 5 is 10 times more acidic than a pH of 6. I think the first one (6ish) is the more accurate result, but the second one (7ish) would be ok for a ballpark test to at least see if a product has a pH of like 10 or something.
I hope this was helpful to some of y'all. I'm going to try to answer comments and get another post chugged out asap. Let me know if you want to see anything!