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Humectants: Which one is preferable?
I am looking to use a humectant which can potentially help in really cutting down on the evaporation of the water in my face cream formula. I have a few options I’ve come across so far outside of the amino acids, if they do in fact have humectant properties (trimethylglycine/betaine?). They are: sorbitol, propylene glycol, glycerin, butyl glycol and dipropylene glycol. I understand that MPG seems to be the least viscous but it does seem to irritate the skin of some users, though I am unsure whether at low concentrations of 3-6% it would still do this to some. I do feel the irritation when used at neat levels. I am wondering if dipropylene glycol would be a good alternative or if one of the other glycols or sorbitol would be an even better option. Any insights?
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14 Replies
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I think the best option is to combine them. PG might be an irritant for some users because it’s also a penetration enhancer and disrupt skin barrier slightly. Great quality for products with active ingredients (I am not suggesting to make any drug claims, just saying it’s used to improve penetration along with such ingredients as IPM, DMI and alcohol). Glycerin is probably one of the most effective but quite tacky. I haven’t noticed a lot of difference with trimethylglycine although I continue using it. Have you tried mixing butylene glycol and glycerin? Depending on the formula you can also add sodium lactate (not if you are using any acrylic acid based rheology modifiers)
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which of the isomers of butyl glycol do I use? 1,3; 1,4; 2,3, etc?
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I wonder if 2% glycerin with 1% butylene glycol will feel tacky
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Glycolysis are less tacky so I would rather do 2% of butylene to 1% of glycerin. I usually do 3% of butylene glycol, 2% of betaine, 1% of glycerin, but I am not fussy about tackiness
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LuisJavier said:I wonder if 2% glycerin with 1% butylene glycol will feel tackyTime to head into the lab and answer your own question.
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Some of the other humectants you can consider would probably be:
- Sodium PCA
- Pentylene Glycol
- 1,2-Hexanediol
- Propanediol
- Methyl Gluceth-20 or Methyl Gluceth-10
- Glycereth-26
I normally will use 1% to 1.5% Glycerin with 1% to 2% Betaine. It’s only slightly tacky at higher humidity like 70+%. In low humidity, it’s far still alright.
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I’ve been struggling to find a supplier of small quantities of hexanediol. I didn’t know that Methyl Gluceth-20 was a humectant; I thought it only functioned as an emulsifier. I might chase up a producer company for some hexylene glycol. Pentylene glycol seems good too although one of my suppliers only offers the natural version which is unattractively expensive in comparison to propylene glycol. Also I tested DPG and I find it is tackier than MPG.
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If this is a cream, you can use glycerin at up to 5% without any sticky afterfeel … all depends on what else is in your formula.
Glycerin + Propanediol or Pentylene Glycol or Butylene Glycol
If you want to avoid using Glycerin you could use Sodium Lactate, Sodium PCA … as mentioned above Betaine or any combination of all of these.
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Thank you Mark
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Be careful with Sodium Lactate and Sodium PCA . Great humectants overall, but if you have acrylic acid-based gellants (Sepinov EMT10, Aristoflex AVC, carbomers etc) these humectants would have a very negative impact on viscosity. Glycerin, Butylene Glycol, Propylene Glycol and 1,3 Propanediol, as well as Betaine don’t cause such issues.
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Sorbitol has quite an effect. Try this:
Take a small sticking plaster and coat the pad with sorbitol. Then stick it to your skin. Take a look after a couple of hours. -
I would have to order the sorbitol first… could you let me know the effect? In any case, I think the glycols are what I will use. They seem considerably cheaper than sorbitol.
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The nice thing about the glycols is that you also get some preservative boost in addition to moisturization/humectancy.
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Very true. I really appreciate that aspect of the glycols.
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