How to get HPMC/CMC to not separate

I make a sulfate free shampoo for limited sale. Till now Guar hydroxypropyltrimonium chloride had sufficed as a thickener, but recently there is a demand to incorporate Salicylic Acid in the shampoo 

To accommodate the very low pH of 4, I've tried both CMC and HPMC in the following formula:

Item %
Water 78.90375
PQ-7 0.7
Panthenol B5 0.1
PEG-7 GC 0.7
ARS Oil 0.3
Vit E 0.1
HPMC 0.5
Coco Glucoside 5.88049
Decyl Glucoside 4.22576
CAPB 5.39
Salicylic Acid 2
Phenoxyethanol 0.6
Potassium Sorbate 0.3
Fragrance 0.3

HPMC in distilled water heated to 60°C and sprinkled into a vortex separates over the course of an hour. When filled in a transparent bottle, the top third is thickened and the solution below is thin as water.

Does anyone have experience using HPMC at such pH levels?


  • I'm also curious as to the difference between CMC and HPMC. There did not appear functional differences between the two. Also would GHPC remain a good fit for this formula or not?
  • @sohaibbg GHPC would work better in a anionic formula, but it depends if you want not only conditioning but also clarity. I never liked celluloses because they don't give much yield value, you could try some of the Carbopols or Synthalens designed for low pH systems. 
  • I will update after trying out "Emrapol 940" that is locally available and seems similar to Carbopol 940 (although detail is sparse online)
  • wet hpmc initially for longer and up percentage to 1.3% works, hpmc appears, from documentation, less compatible with APGs, hence increasing percentage may help. I will however be switching to emrapol 940 due to it contributing a desired lubrication effect while shampooing, good against hair breakage.
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