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Potassium sorbate
Hello,
I have a question that may seem stupid regarding formulating with potassium sorbate. In order to use potassium sorbate you need to formulate a solution by mixing it with water typically a 25% solution. I would like to add 0.1% to 0.2% of potassium sorbate to a liter of lotion that’s already preserved with phenoxyethenol for added protection against yeast and mold. My question is do I multiply the 0.2% since the potassium sorbate is only a 25% solution or is the 25% solution used as if it is 100%? I’ve looked online but all I see is the recommended usage rate. -
5 Replies
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To achieve 0.2% concentration in your product you require to use 4 times the amount of 25% solution which is 0.8% in product.
Why are you adding the sorbate at this stage? It is far better to add during mixing before emulsfication to ensure adequate distribution in the product.
If it is completely necessary to add at this late time you would be best using trituration for mixing. To do this, place the required amount of your sorbate solution in a vessel large enough to contain the total amount of product and add an equal quantity of the finished lotion. Mix well. The lotion may split at this stage with the high content of electrolyte, but persevere. Next add double the amount of lotion and likewise mix well. Next add double the previous amount of lotion. By doubling up at each addition (geometric progression) you will soon have the whole amount of lotion mixed and the sorbate evenly distributed.
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K-sorbate is active at 5-5.5 PH the Pka of sorbic acid and it discolors (violet/blue) in storage at 50C after two weeks equivalent to one year at ambient RT.I would choose another preservative for your system.
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Thank you @johnb for this information. I kinda thought that 0.8% would be the correct amount. To answer your question I purchased a liter of a simple lotion base to add my own ingredients to. While I do make alot of formulas from scratch serums, salves, toners, etc I have yet to make a lotion from start to finish and I am a little intimidated by it. I feel more comfortable at this time to buy a base of lotion to add my own tinctures, glycerites and infusions into. Thank you for the mixing info I wouldn’t of thought to do that I will give it a try and see how it goes!
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The trituration method is applicable to all mixing of small into large quantities. It is easy to do (it takes longer to describe than it does to carry it out) an, when done properly, ensures to have a well mixed product.
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Thank you @DRBOB@VERDIENT.BIZ for bringing that to my attention because after looking at the pH the potassium sorbate is useless to me anyhow since my lotion’s pH is 7.
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