In this post, Dawn asks: Susan, I noticed you are using glycerin and not hydrovance in the dry skin formulations. Is glycerin a better product for extremely dry skin? I love hydrovance but if there is an advantage to using glycerin with the dry skin issue, I'd like to formulate the most effective lotion. I apologize if this is redundant. You may have addressed this and I missed it. I hope not. Your blog is my "go to" after consulting other sources. I admire your commitment to researching so completely! Thanks for your help with this!!
I'm blushing, Dawn. Thank you for your lovely comments!
Hydrovance is a great humectant! It contains urea, which is fantastic for dry skin, and it doesn't feel sticky like glycerin might feel in creations like toners or body sprays. The main problem is that Hydrovance has a pH of 6.5 to 8.5, and it can experience pH drift in our products, meaning it can go from the lower, just about neutral pH to the higher, slightly alkaline pH, which can mess with our skin, as well as things like preservatives or other ingredients that need to have an acidic environment. As is noted in this data bulletin, you're better using Hydrovance with a neutral product around pH 7. (Click on the data bulletin for more information on preventing this pH drift!) If you're using Hydrovance, you really need to know this!
I like Hydrovance and I use it regularly in things like my toners - the ones without AHA or Multifruit BSC (those are generally quite acidic) - and cooling sprays, but I don't like to recommend it to newbie-ish formulators or formulators who might not have a pH meter to take all of this into account.
Is Hydrovance a better humectant than glycerin? Possibly, and the idea of "is this better than something else?" is such a subjective thing at times! All the humectants draw water from the atmosphere, and some do it better than others, but there are other things to consider - personal philosophy (for instance, for things like propylene glycol), other benefits to our skin, change of product viscosity, change in feel of produt, and so on - so the concept of better has to include all those things! (I hate to sound pedantic, but it really is more of a subjective thing!) Urea is a great humectant and, like sodium lactate, we find it in the natural moisturizing factor in our skin. Glycerin has a ton of other benefits - click here for that post - but the stickiness can put people off. It's one of the most inexpensive humectants, and it's easy to find at every supplier. If you can control the pH drift, Hydrovance is a great choice. If you can't, then any of the other humectants are a better choice.
read the data bulletin well and learn how to prevent that pH drift. Or use it in a product that has a neutral pH and use it quickly. (The pH drift is very significant, if you look at the chart in the data bulletin. It can drift upwards 1.5 pH units over 12 weeks, which could take you from 6.5 to 8, which would make some of our preservatives ineffective. That's pretty significant! And it could mess with your hair and skin - for instance, our hair likes products that are lower than 6.5. If we used Hydrovance (which I don't see in a hair care product, but you never know) in a shampoo, we'd go from a slightly acidic product to an alkaline product, which our hair hates! I could go on, but I think you get the picture! If you're using Hydrovance, please read this bulletin and follow the directions!
Thanks for the great question, Dawn!
What does pH mean? (And what does it mean when we refer to our skin?)
Adjusting the pH of our products.
Question: pH and bath products
Humectants: Hydrovance vs. urea