Well, after many failed attempts using a Carbomer to thicken up a formula I finally decided to take a look at Cellulose Thickeners. More specifically I've been working with MethylCellulose and Hydroxyethylcellulose. I am using 1% Cellulose with 1% Triethanolamine to thicken and getting great results. No more air bubbles or stringy flow!!
My only question is really with regards to stability and preservation. We normally use a DMDM to preserve, but a few years back had a bad batch due to excessive use of Xantham Gum. Do the cellulose thickeners need any special preservation techniques? Or anything else which help enhance a formula's stability.
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Here is an ingredient list for their KY Liquid 5oz offering:
Water, Glycerin, Sorbitol, Propylene Glycol, Hydroxyethylcellulose, Benzoic Acid, Methylparaben, Sodium Hydroxide
They use Benzoic Acid and Methylparaben as the preservatives.
I use cellulose based thickeners as secondary thickeners on occasion and I have been exploring the idea of using them as a primary thicker as well. Many of my formulations require low pH's (3-4) though, so I am curious, do cellulosic thickeners function well at this low of a pH? If so, which would you recommend as a primary thickener?