DIY (do it yourself) allows the consumer to be creative and make a product that is designed to his/her liking.
But DIY also allows the consumer to evade limits to the concentration of ingredients, including those affecting acidity and toxicity of the final products. Don’t!
Unless you are a chemist and MD, you are unlikely to know enough to avoid costly mistakes. This is especially true about “hacking” skincare products using the ingredient lists. You may not notice the word “sodium hydroxide” towards the end of an ingredient list that includes glycolic acid and says on its label “70% glycolic acid peel”. Now, they even omit the strong base on the label, but remember that the “chamomile extract” can have anything in it. You can’t possibly apply 70% glycolic acid to your skin without burning it.
I know I complain in my blog posts about how silly some formulations, sold at ridiculously high prices, can be. But even then, those products are unlikely to cause immediate harm. Those acne products with benzoyl peroxide will age your skin but it will take a while to show the damage. But just one mistake made in your kitchen using an acid bought on Ebay or amazon could end up with you in the ER.
What to do? Avoid working with strong acids. Even weak acids, like ascorbic acid, can be tricky. Even better, reserve your creative power for serums, creams and cleansers.
If you insist in using acids in your DIY, make sure you use protective clothing like gloves and a thick, preferably waterproof apron, and have a pH testing device on hand. You can use pH paper like those sold for pool water testing, or pH meters, that are now so affordable and easy to use. The paper strips are very easy to use and you need just a drop of liquid to use, while pH meter need enough volume to submerge the tip of the instrument.
Always remember that your skin is alive and can be damage. True, it has immense recovery power, but immense does not mean unlimited.
Becker FF, Langford FP, Rubin MG, Speelman P. (1996) A histological comparison of 50% and 70% glycolic acid peels using solutions with various pHs. Dermatol Surg. 22(5):463-5. doi: 10.1111/j.1524-4725.1996.tb00348.x. PMID: 8634810.
Sharad J. Glycolic acid peel therapy – a current review.(2013) Clin Cosmet Investig Dermatol. 2013;6:281-288. doi:10.2147/CCID.S34029