Why didn't my lotion thicken properly?

As a cosmetic scientist with a home-based business, I have successfully produced many gallons of lotion over the last four years using a combination of aloe vera juice, glycerin, low and high HLB emulsifiers, butters, oils, and optiphen plus as my preservative. Yesterday I (somewhat presumptuously) substituted a refined coconut oil in place of my usual EV organic coconut oil because of a limited supply of the good stuff, and my lotion, upon cooling to room temperature, is only slightly more viscous than water. What happened? I heated and held the water phase at 160F for 20 minutes, I combined and shear mixed the two phases once they were both at this temperature, I added the optiphen once the mixture was below 100F, and I have a perfectly stable emulsion. It is just the wrong viscosity. I noticed that the coconut oil contains TBHQ (antioxidant), citric acid, and dimethylpolysiloxane (antifoaming agent). Is one of these the culprit? I dread the idea of reheating the lotion to add more thickeners and potentially volatilizing some or all of the phenoxyethanol in the process, but this may be my only solution. Does anyone have any suggestions for salvaging my watery lotion?

Comments

  • One suggestion maybe is adding a post-emulsion thickener like Sodium polyacrylate (Covacryl MV60). Coconut oil is a little problematic to handle really.
  • it's the dimethylpolysiloxane. Your coconut oil was designed for the chip pan.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • Chemist77Chemist77 Member, PCF student
    Try Sepigel 305 or Dow Corning RM 2051 or Rapithix A60 although my personal choice would be Sepigel 305 because of the feel and the body/structure it provides to the formula. 
    Just hoping that you don't have any cationics.
  • BobzchemistBobzchemist Member, PCF student
    On a production level, I would make new batches and blend-off about 10-20% of the bad batch each time. If you are selling this, your consistent customers will notice the difference if you fix the batch any other way.

    The only way around this, in my opinion, is to make it a new product. It's water-thin, so it could be a sprayable emulsion. Or, you can add a sensorial thickener to give the product an unique feel, and sell it in a different package.
    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."
  • PerryPerry Administrator, Professional Chemist
    Yes, if you're selling the product you can't add a new ingredient to thicken it unless you change the ingredient listing on your label.  Blending off as @Bobzchemist suggested is your best option.
  • Thanks, guys. I like Bobzchemist's blend-off or new product idea. I definitely don't want to change the labels to include a new ingredient, and I don't want to alter the feel of the product since I have a loyal following for my original formula. I may blend off part of it and experiment with the rest using some sodium polyacrylate that I have on hand.
  • BobzchemistBobzchemist Member, PCF student
    @erindlea, you'd be surprised at how discerning a regular customer can be. Sometimes, something you'll think is a minor change will stick out like a sore thumb...
    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."
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