Home Cosmetic Science Talk Formulating Switching betaine to sultaine (stability issue)

  • Switching betaine to sultaine (stability issue)

    Posted by SkinNP on March 6, 2019 at 4:07 am

    I have a facial cleansing formula that passed stability testing with surfactant system consisting of 70% cocamidopropyl betaine and 30% coco glucoside (by solids). I tried swapping sultaine for betaine, with no other changes to the formula, and adjusted to same pH (5.0). The sultaine-replaced product had obvious separation at 40C and RT by day 2. Can anyone think of a reason this might have occurred?

    I admit I have not duplicated the failed result, and intend to attempt it tomorrow, but thought I’d check if anyone has insight. Thanks in advance.

    SkinNP replied 4 years, 9 months ago 6 Members · 10 Replies
  • 10 Replies
  • SkinNP

    Member
    March 14, 2019 at 4:06 pm

    Update: I duplicated the failure, and appears to me that xanthan gum is settling to the bottom. I again made the stable cleanser formula with exactly the same process and % solids, except that I replaced cocamidopropyl betaine with cocamidopropyl hydroxysultaine. I adjusted pH to 5.4 and let the solution sit overnight at RT before the final step of adjusting viscosity with xanthan gum (pre-wetted with glycerin). Looked like a gorgeous solution the next morning, until I added the xanthan gum. Despite what I consider adequate mixing, I have an opaque layer at the bottom of the vessel that appeared within an hour or two — it’s about 15% the total height of the mixture. Wondering if anyone has any thoughts how to correct this, or an alternative thickener for sultaine + coco glucoside that would have an EWG hazard score no higher than 2?

  • belassi

    Member
    March 14, 2019 at 4:19 pm

    EWG? EWG??????@!@!!! Words fail me.

  • oldperry

    Member
    March 14, 2019 at 5:13 pm

    It is difficult to give you any advice without knowing all the ingredients in the formula.

  • Sunstone

    Member
    March 14, 2019 at 8:43 pm

    Belassi said:

    EWG? EWG??????@!@!!! Words fail me.

    It’s a trend these days to have formulas that only use ingredients approved by larger sites like EWG. There are products out there that claim to use only green-labeled (for safe) ingredients, like the Purito Centella Green Level Buffet Serum, which is very funny because the enormous amounts of lavender oil in it irritated my skin. Just shows that it’s the dose that makes the poison!
    I think this trend will go away quickly, for what it’s worth.
  • ngarayeva001

    Member
    March 15, 2019 at 6:18 am

    Xanthan gum is anionic, CAPB changes it’s charge to cationic at pH lower than 6. You have a conflict of charges here so xanthan separates. I haven’t worked with sultaine but assuming all amphoterics are similar elevate pH to 7 and see whether it passes stability.

  • ngarayeva001

    Member
    March 15, 2019 at 7:57 am

    And speaking about thickeners, that formula is going to be tricky (glucosides….) - crothix liquid is the king

  • SkinNP

    Member
    March 15, 2019 at 12:45 pm

    Many thanks to ngarayeva001 for the professional and helpful posts. I was considering Crothix…

  • jrusso531

    Member
    March 28, 2019 at 3:16 pm

    Crothix is a 3 on EWG. It is also a PEG ingredient. 

  • ngarayeva001

    Member
    March 28, 2019 at 10:51 pm

    @jrusso531

    1) EWG is a scam. 
    2) Yes, it is PEG, and?

  • SkinNP

    Member
    May 18, 2019 at 7:36 pm

    Just an update for anyone having difficulty replacing betaine with sultaine:

    In my further work, higher pH (7.8) did not improve stability of the sultaine formula. HEC, HPMC, and carbomer were similar failures. Crothix Liquid looked very nice until showing subtle precipitate after about 1 month in 50C. I found that NaCl level was 5% in my CAPB, and close to 7% in my CBS… so I decreased the amount of CBS as compared to the CAPB in the original formula. This seems to help some. Reducing the amount of EO helped much more. Still working on it.

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