Home Cosmetic Science Talk Formulating why is gluconolactone crystallizing out of solution?

  • why is gluconolactone crystallizing out of solution?

    Posted by Alison on July 12, 2022 at 1:44 pm

    After 2 days I’ve noticed tiny crystals from the addition of gluonolactone that won’t dissolve upon shaking. Why is this happening? Will the crystals irritate the skin if still used? Is this a problem?

    Formula is below: 

    aloe water
    peppermint hydrosol
    lavender hydrosol
    witch hazel distillate
    hydrolized oats
    cucumber extract
    allantoin
    potassium sorbate
    gluconolacctone

    Thank you.

    PhilGeis replied 1 year, 7 months ago 6 Members · 8 Replies
  • 8 Replies
  • Microformulation

    Member
    July 12, 2022 at 2:08 pm
    You would need to include percentages since this is a solubility issue.
    Lacking this, I would suggest Allantoin is your culprit, not the Gluconolactone.
  • Alison

    Member
    July 12, 2022 at 2:23 pm

    Hi Microformulation, 

    I’ve kept the gluconolactone very low at 0.3%, potassium sorbate also at 0.3% and allantoin at 0.5%. Some of the allantoin settles at the bottom as a white powder. However, the crystallization is a new experience since the addition of gluconolactone (which I had not been using before). 

  • Cdsgames

    Member
    July 12, 2022 at 4:36 pm

    Did you measure the PH ?

  • Alison

    Member
    July 12, 2022 at 5:23 pm

    pH is 4.62

  • Microformulation

    Member
    July 12, 2022 at 7:46 pm

    Alison said:

    Hi Microformulation, 

    I’ve kept the gluconolactone very low at 0.3%, potassium sorbate also at 0.3% and allantoin at 0.5%. Some of the allantoin settles at the bottom as a white powder. However, the crystallization is a new experience since the addition of gluconolactone (which I had not been using before). 

    So, you have some undissolved Allantoin in the product?

  • MarkBroussard

    Member
    July 12, 2022 at 8:16 pm

    @Alison

    You have to heat to about 50C for the Allantoin to dissolve properly

  • kivangel

    Member
    November 16, 2022 at 3:45 pm

    Undissolved Allantoin needs to be fixed, as others mentioned by heating. Also, its solubility in water is around 0.5% so you are at the upper limit in your formula.

    Since you say crystals formed only after adding Gluconolactone, I think this may be due to Sorbic Acid (from Potassium Sorbate) crystalizing out of your solution due to low pH. Check this out for more info:
    https://www.jungbunzlauer.com/fileadmin/content/_PDF/PRINT_PROJECTS/Flyer/JBL_FL_How_to_use_Glucono-delta-Lactone_in_Personal_Care_2022-071.pdf
    “Salts of organic acids used as preservative dissociate when added in solution. The addition of gluconolactone can lead to a drop of pH under the pKa. The undissociated form of the preservative becomes predominant (e.g. benzoic acid). Having a low water solubility, the acid form of the preservative starts to crystalize.”

  • PhilGeis

    Member
    November 16, 2022 at 4:39 pm

    Sorbate is not enough of a preservative with or without gluconolactone.  Please consider something more effective vs Gram negative bacteria.

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