How are these alcohol-based hand sanitisers moisturising?

helenhelenhelenhelen Member
edited December 2020 in General
Background - I'm not trying to make a hand sanitiser but I'm just interested as a consumer how some simple alcohol-based hand sanitisers are more moisturising on my hands than most creams I've ever used on my dry hands. I've noticed a similar effect from other communal (and thus probably cheap) hand sanitisers I've used in public places.

I was in a store today and had to use their hand sanitiser on the way in. It felt really nice on my hands.. silky and not sticky or slimey. I noted the brand name of the bottle on the way out so I could look up the ingredients out of interest.

It was this product: https://ingenialifesolutions.com/product/hand-sanitiser-gel-500ml/

"Ethanol Ethyl Alcohol, Xanthan Gum, Glycerol, Isopropyl Alcohol, Denathonium Benzoate (Bitrex), Aloe Vera"

I'm not sure that is a proper INCI list as it doesn't look quite right - "glycerol" instead of "glycerin" and a typo in the Bitrex ingredient. But that's what is listed on the back of the pack in the product photo.

When I have used hand sanitisers that have felt similar to this one, the moisturising effect even lasts through later washes with the skin feeling hydrated and not papery at all. Is it really just glycerin doing this? I have used moisturisers with high glycerin (15% or above) and while they feel moisturising on, the effect is mostly washed out after the next rinse with water, leaving the upper layer of skin feeling papery and as cracked as before. I also wouldn't get lasting moisturisation with a plain glycerin and water mix.

Note - I don't get this lasting moisturising effect from all alcohol-based sanitisers.. most dry my skin out instantly. But there have been a few "public" ones recently where I have really noticed a high moisturisation effect and no drying out at all.. which is quite a feat on my ridiculously dry hands. Any ideas on how they do it?

Comments

  • My guess would be the mix of xanthan gum with the glycerin? 

    When it is was serious Covid times earlier on i had made a 60% IPA gel with Sepimax Zen and Methyl Gluceth-20 (just 0.5%). It's not very drying compared to liquid no-gel types, and the guys at work use it multiple times a day, every time they are back from their smoke break. 
  • jemolian said:
    My guess would be the mix of xanthan gum with the glycerin? 

    When it is was serious Covid times earlier on i had made a 60% IPA gel with Sepimax Zen and Methyl Gluceth-20 (just 0.5%). It's not very drying compared to liquid no-gel types, and the guys at work use it multiple times a day, every time they are back from their smoke break. 
    Thanks @jemolian, you're probably right. I wonder how much glycerin is in the hand sanitiser I used to get the effect I experienced.
  • You can consider batch testing 0.5% to 2% to see if you get the same effect with a gelling agent :) I believe the lubrizol sample formulations are around that range for humectants that are added.  
  • @helenhelen You probably experienced an indirect effect of carbomers (which deposit on skin creating a film that holds water molecules), and some other polymers added (like PEG-12 dimethicone). I don't think small molecules like Glycerin would give a perceivable effect, considering they penetrate the skin very fast and that the level used in these type of products is very low. Actually, I'd be cautious about using these type of humectants in hand sanitizers, since the are proved to reduce the potency of alcohol. Even the FDA issued a recommendation about it and some other actives usually found in hand sanitizers (like Aloe Vera).
  • ketchito said:
    @helenhelen You probably experienced an indirect effect of carbomers (which deposit on skin creating a film that holds water molecules), and some other polymers added (like PEG-12 dimethicone). I don't think small molecules like Glycerin would give a perceivable effect, considering they penetrate the skin very fast and that the level used in these type of products is very low. Actually, I'd be cautious about using these type of humectants in hand sanitizers, since the are proved to reduce the potency of alcohol. Even the FDA issued a recommendation about it and some other actives usually found in hand sanitizers (like Aloe Vera).
    Hi @ketchito Thanks for the info. Yes I have experienced the effect of carbomers and sodium polyacrylate holding water on the skin lately. Much more so than with xanthan. So I was surprised that the ingredients list didn't include any gel formers other than xanthan. I actually just saw the warnings about glycerin reducing the sanitising effect of alcohol the other day after I posted this thread.. even very small amounts of glycerin. Made me wonder if there are a lot of ineffective hand sanitisers out there!
  • chemicalmattchemicalmatt Member, Professional Chemist
    @helenhelen and @ketchito I'll add here that butylene glycol will detackify just about any humectant, though a negligible humectant itself, at a low level too. (Your other thread about glycols is refenced here too.) Butylene glycol has always been the most versatile of the lower glycols for this reason. It has zero antimicrobial activity though. It also detacks sticky things like xanthan, acrylate polymer films. If you liked that formula you posted, you'll like it even better with a bit of BG.

  • PerryPerry Administrator, Professional Chemist
    One piece of this puzzle that you are missing is that "moisturization" isn't merely a thing you can measure in a lab with an instrument. Much of your perception of moisturization is created during the experience of using a product. There may just be something about the process of using hand sanitizers or the feel of the alcohol or the product that convinces your brain that it is more moisturizing. When in reality, it may not actually be more moisturizing in any objectively measurable way. 

    This happens a lot with cosmetics.
  • Good point made by Perry about perception. I made a little bit of hand wash in work and some colleagues kindly offered to try it out. They said it made their hands feel 'soft' whereas I perceived it as 'drying' (though I had tried approximately 20 minor variations that day so probably had something to do with it...).
  • Thank you for your comments @chemicalmatt, @Perry and @Benz3ne.

    @Perry for me, "moisturised" means skin that doesn't look and feel like parchment paper, and the comfort lasts through a wash instead of being rinsed off. The sanitiser made my hands look and feel like a normal person's hands. I just don't seem to have any natural moisture or oil going to my hands and feet!
  • Thank you for your comments @chemicalmatt, @Perry and @Benz3ne.

    @Perry for me, "moisturised" means skin that doesn't look and feel like parchment paper, and the comfort lasts through a wash instead of being rinsed off. The sanitiser made my hands look and feel like a normal person's hands. I just don't seem to have any natural moisture or oil going to my hands and feet!
    Could it be that the combination of ethanol and glycerin aids penetration of glycerin? Or that xanthan forms a film and retains glycerin, so re-rinsing is just wetting and allowing that film to form again, or 'rehydrate' the humectant?
  • Benz3ne said:
    Could it be that the combination of ethanol and glycerin aids penetration of glycerin? Or that xanthan forms a film and retains glycerin, so re-rinsing is just wetting and allowing that film to form again, or 'rehydrate' the humectant?
    Yes it must be something like that. I should probably try a very basic gel with just glycerin and xanthan to see if I get the same result.
  • Benz3ne said:
    Could it be that the combination of ethanol and glycerin aids penetration of glycerin? Or that xanthan forms a film and retains glycerin, so re-rinsing is just wetting and allowing that film to form again, or 'rehydrate' the humectant?
    Yes it must be something like that. I should probably try a very basic gel with just glycerin and xanthan to see if I get the same result.
    That sounds like a nice approach. I'm curious as to how much ethanol is actually in there, whether it's expressed as 75% v/v or w/w, or whether their raw ethanol was a lower concentration to begin with i.e. DEB96 vs DEB100.
    My understanding is that xanthan gum will precipitate with higher quantities of ethanol (i.e. solubility drops). Unless there are functionalised or high-viscosity xanthan gums available that I'm unaware of...
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