Product darkening

Hi, I am having a problem with my face pads darkening after abou two weeks. I have done quite a lot of research, and even changed some of the ingredients. I used to use aloe juice, but switched it to a high quality organic freeze dried powder. I look into each ingredient, and I saw one article about how the vitamin c could be the cause. The formula ph is 3.5. Here is the ingredient list, Organic Whole Leaf Aloe Barbadenis (Organic Aloe), Organic Salix Alba Extract (Willow Bark), Organic Witch Hazel, Organic Orange Blossom Water, Vitamin C (L-Ascorbic Acid), Glycolic Acid, Vegan Hyaluronic Acid, Non-Synthetic Vitamin E (D-Alpha-Tocopherol).

If the vitamin c is the cause, do you think replacing it with Kakadu plum extract would be a good idea? I have read that it is very high in vitamin c. I also looked into using sodium ascorbyl phosphate, but it has an optimal ph of 5-6, so I'm not sure if it will cause darkening to occur as well.

Thank you for any help! I really appreciate it!

Comments

  • It is vitamin C. And Kakadu extract darkens too. Everything with vitamin C changes color unless it's sufficiently protected. Even then, you can only delay oxidation, not prevent or stop it. 

  • Thank you! Do you have any suggestions as a preservative for the vitamin c?
  • You'll need to prepare a buffer system (sodium citrate+citric acid) to stabilize the vitamin C. You can request from you supplier. 
  • I wanted to give an update on the formula. I was able to get the new formulation made today, which uses much less vitamin c, and already it is looking much clearer than any previous version. I will update in a week to note if any yellowing or darkening occurs. Thank you all for the help!
  • PerryPerry Administrator, Professional Chemist
    Thanks for the follow-up

  • Vin  How exactly does one use a buffer to stabilize it? do we just add an equal amount of sodium citrat + citric acid buffer as ascorbic acid to the final forumlation? or pre dissolve the ascorbic acid into the buffer? sorry this is such a basic question! i feel like i should know this but i dont! :(
  • @billichemist..... It depends on your formulation, 0.5% - 5% of Sodium citrate is enough.
  • or you can use the Henderson-Hasselbach Equation to compute the amount of citric acid and sodium citrate that you need to use at a specific pH.
    Formulator. Currently specializes in formulating natural cosmetics.
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