Lotion Whitening on Rub In - Possible Sources and Preventions? - Cosmetic Science Talk

Lotion Whitening on Rub In - Possible Sources and Preventions?

edited May 2014 in Formulating
So, I was recently asked by a colleague, why do some lotions whiten when you rub them in and others don't. Now, I have always been taught that it is bad if a skincare lotion whitens as you rub it in, as that is the sign of a cheaper/low end lotion but to be honest I'm not quite sure what the cause of it is. Is it due to a soaping out effect? For example is it due to a higher portion of saponifiable vs unsaponifiable content? Aka too many esters in the presence of NaOH? Could this be prevented by switching to a weaker base such as TEA (triethanolamine)?

Any advice would be appreciated! I tried searching the literature, but I did not have very much luck and at this point I am only speculating.

Comments

  • How about adding dimethicone to the formula, little goes a long way.
  • Thank you for the suggestion! To be honest though, its not a problem in my formulas :) I love silicones. My colleague on the other hand works with Silicone free formulas. I am also concerned about the source of the whitening. Do you know what causes it?
  • The soap of course as you mentioned, though I have seen even those neutralized with TEA give the whitening effect if it is a soap based lotion e.g. TEA Stearate soap. If you want to eliminate this problem then the whole oil phase has to be changed. In fact then there remains no possibility to have an anionic lotion, though I hope other senior mentors could throw a better approach on this if I am wrong.
  • gfeldman, the condition you describe is "soaping" as surmised.  It is not necessarily derived from the use of cheap ingredients, just the many anionic emulsifiers that are based on saponification (e.g. TEA-Stearic acid) and their low MW esters (e.g. glyceryl stearate). Formulas containing foaming surfactants will contribute to this as well (e.g. glucosides). You do not have to change your entire oil phase either; just add cetyl alcohol and the whitening will diminish significantly.  Be advised the viscosity will increase significantly as well.  I know I have adressed this issue here in the past, so I now have the CSNY song "Deja Vu" in my head ..."we have all been here before..."
  • I've never heard about increasing cetyl alcohol to reduce whitening, thanks chemicalmatt!, I will definitely try it in a formula I'm working on. It's a "natural" formula with no PEG emulsifiers and no silicones. For this reason, I've been looking around for ways of solving this issue. 

    So far I've found raw materials that claim to help address the soaping effect. Some examples are silicone replacements like Softolive from Soliance and Olive LD SP from Clariant. I've tried changing my emulsifier with Simulgreen from Seppic. I've even tried replacing waxes like stearyl alcohol and stearic acid with things like Cutina HVG from BASF and Compritol 888 from Gattefosse...but nothing has worked so far!  What has worked so far is adding 1% dimethicone, but unfortunately I can't include it in my formula.

    I found an interesting article from BASF explaining that the soaping effect is due to friction foam?? but still I haven't been able to fully understand why this happens.


  • I'm not sure I agree with that article. It may help to try to imagine what is going on when you rub an emulsion into your skin.

    First, the emulsion mixes with everything else on the skin - water, salt, sebum, etc. Next, as you continue rubbing, two things are happening: 1) The water in the emulsion starts to evaporate, and some part of it is also taken up by the skin. 2) A great deal of shear force/stress is being applied to the emulsion -more than enough to re-emulsify the product. That's what I think is happening - as the water level in the emulsion drops, the emulsion turns from an O/W emulsion to a W/O emulsion, and only then to an emollient film, as the water level drops further.

    I'd love to hear other people's opinions on this. 
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • @Bobzchemist Great explanation, so it means the whiteness can be attributed to the leftover oils and waxes once the water part has vanished (for reasons you mentioned).
  • @milliachemist, yes, I think the whiteness comes from re-emulsification. The products that do not have this happen are formulated so that they are not able to form w/o emulsions regardless of how little water is available.
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • @Bobzchemist I think its a very plausible and acceptable explanation, so that means in those products the level of emulsifiers would be comparatively low or weak emulsifiers would be there which are unable to produce such white effect.
  • That is interesting.  Would emulsifiers with a higher HLB requirement be less likely invert to w/o and thus to soap?  I am running into this issue with a chassis that I have used several times: olivem 1000 (hlb 9) with cetearyl alcohol.  The only difference now is that I am not using dimethicone, which I think suppresses soaping.  Do you think Cetyl Alcohol will help because it's hlb is significantly higher? 
  • @jjclii:

    Olivem 1000 very readily soaps ... Cetyl Alcohol at 1% helps, but does not prevent it entirely.  What I have found helpful is to use a blend of Olivem 1000 with RitaMulse and add a plant-based silicone replacement such as Isoamyl Laurate ... give a really nice, light cream/lotion.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    Provides Formulation Development and Lab-Scale Contract Manufacturing Services.  See website for details www.desertinbloomcosmeticslab.com

  • That's great, thanks.  I increased the oil content and it significantly reduced.  I like your suggestions.  
  • Thanks for the wonderful advice.
  • Hola, sugiero ver este enlace 
  • the basic issue is penetration into the epidermis regardless of emulsion type which is why silicones and silicone replacements work Have done numerous consumer product tests and result is always the same--ie rapid penetration during rub--in/shear.
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