Home Cosmetic Science Talk Formulating Stability of Formulation.

  • Stability of Formulation.

    Posted by palash1865 on May 11, 2015 at 6:19 pm

    Hello all,

    I’ve recently formulated a shampoo with the following ingredients.
    Water,SLES,SLS,PQ 10,Salt,EGDS,CAPB,Cocamide DEA,Amodimethicone,GHTC and DMDM hydantoin and fragrance.
    Consistency of the shampoo on the first day is excellent, but the shampoo is not at all stable and becomes thin the very next day itself.
    What can I do to avoid this?
    perspicacious replied 9 years, 1 month ago 7 Members · 14 Replies
  • 14 Replies
  • belassi

    May 11, 2015 at 6:27 pm

    First try making it without the fragrance and see if it remains stable. I noted this effect myself with some fragrances. What % fragrance oil are you using?

  • palash1865

    May 11, 2015 at 7:13 pm

    0.25 % of fragrance.

  • OldPerry

    May 11, 2015 at 8:03 pm

    Reduce the level of Amodimethicone could help too.

  • belassi

    May 11, 2015 at 8:28 pm

    At 0.25% (low compared with my usage, I put 1% fragrance oil in) I doubt it’s the fragrance … you DO mean fragrance oil and not essential oil, right?

  • billichemist

    May 11, 2015 at 11:21 pm

    Ive had a similar problem too and the lovely people on this forum helped me out.

    i had a similar formula of ALS, CAPB and CocoDEA and it would be beautiful and thick the first day and thin the next. ( i think it was my EO blend too)
    but some one told me to readjust my levels and do away with CocoDEA completely and use a solubiliser for the oils.  and its fixed! the thread is in there somewhere in the forums… it was posted not long ago so you should be able to find the thread easy enoguh..
  • Chemist77

    May 12, 2015 at 12:34 pm

    Try once without Amodimethicone, I am guessing that as the culprit.

  • palash1865

    May 13, 2015 at 2:54 am

    Currently, I am using 2% amodimethicone by wt. I’ll make batches with 0 and 1%. Though, I thought that EGDS might be the reason as to why viscosity is decreasing. I read that pearlescent shampoos are prone to this.

    And yes 0.25% of fragrance oil.
  • Chemist77

    May 13, 2015 at 3:02 am

    On contrary I have this perception that pearlized variants are more viscous although there is no hard nd fast rules, it depends on how u formulate. Btw that 2% Amodimethicone is way too much for a shampoo, did u check the PDS???:

  • ozgirl

    May 13, 2015 at 3:09 am

    Pearlescent shampoos / body washes need a minimum viscosity and specific gravity to keep the pearlescent suspended. So that might be where the perception that pearlized variants are more viscous comes from.

  • palash1865

    May 13, 2015 at 3:43 am

    “Glycol distearate and polyethylene glycol distearate are used as pearlizing agents
    either alone or combined with cetanol or oleyl alcohol. Pearl shampoos are prone to
    separation and viscosity drops and are difficult to maintain stable. Measures should
    be implemented to increase the viscosity and ensure stability, such as adding salt
    and selecting appropriate cationic polymers and anionic surfactants. “

    This is from formulas,ingredients,and production of cosmetics by hiroshi iwata.

    And yes, I’ve checked. A lot of shampoos have around 1.5-2.5% of amodimethicone.

  • belassi

    May 13, 2015 at 5:47 am

    It’s not the fragrance oil. Not at that percentage. I suspect the salt curve isn’t stable, drifting one way or the other. I would get rid of the DEA for sure. Since you are making a pearlised shampoo, sub MEA for the DEA and adjust pH. . . WAIT a minute! Where in your list is the pH adjuster - DEA in the formula and no pH adjustment???

  • palash1865

    May 13, 2015 at 6:27 am

    I wasn’t using DEA initially. Then the pH was 5.5. Shampoo wasn’t foaming well,so i added DEA but completely forgot to adjust pH. Thank you for pointing it out.

    I’ll sub MEA for the DEA.
    But this would solve stability issues?
  • Chemist77

    May 13, 2015 at 10:36 am

    Well you surely can add that percentage by changing to hot process shampoo, its more appealing and robust for such ingredients as your dimethicone.
    Good luck.

  • perspicacious

    May 13, 2015 at 2:45 pm

    You need to be careful with your salt concentration. There is a curve which defines its thickening ability and past a certain amount (3 percent plus is often the danger zone) the viscosity of your formulation loses stability (curve goes down). With DEA or MEA that thickening stability is more critical because they are electrolytes as well. Experiment by slowly adding the salt (add it last) until you understand its limitations for this particular formula. Then stay below that point where instability begins.

    Salt for thickening can be tricky getting the right balance. Maybe you should rely on one of the many cold process gelling agents which are readily available.

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