Stearic acid based shave cream that is thicker when hot? - Cosmetic Science Talk

Stearic acid based shave cream that is thicker when hot?

edited October 2014 in Formulating
I am working on a stearic acid based shave cream that becomes so thick it's almost solid at 55-60C, but when it gets to room temp the viscosity significantly decreases to ~50,000 cPs.

Notes:
~70% Water
~5% Sodium Lauroyl Methyl Isethionate
~15% Stearic Acid
~.5% Potassium Hydroxide
Water phase and oil phase are heated to ~75C (surfactant in water phase) and combined hot via 3 blade prop. Neutralized with potassium hydroxide shortly after combining.
Final product pH is 6.5-7

Right now my concern is scale up, but I was curious if anyone had seen or knew why this phenomena existed (as I have never seen it before).

Comments

  • Yes I have seen this before, try finishing it with an excess of Stearic and neutralise it further when cooler
  • I ended up neutralizing with more Potassium Hydroxide as the viscosity got too thick during cool down. Worked out better from a processing perspective but I did have to homogenize at the end to make the product uniform (turned out pretty lumpy). I kept track of the total amount of potassium hydroxide added, so I'm going to try to add it all right away and see what happens.
  • Don't use 3 blade prop. to mix your batch. use a Silverson Homogenizer.
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