Teach Soap

I'm having problems with change in viscosity over time. I made the viscosity the same as Caprice, it takes 40 sec. to pour through the cup. Then two days later it is noticeably thinner and it pours in 20 sec. Completely baffled.

Does the pH shift as well? I have used a blend of D-Glucono-1,5, lactone and sodium benzoate as a preservative to test and the pH changes downward over time, which changed the viscosity of my lotion.

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Irena
Closed minds are like faulty parachutes; they refuse to open.

Good suggestion, thanks for that. Unfortunately I am almost out of pH strips. I have a few M&N 4-bar type, so I just tried one. It could be that the pH changed a little, it was at 5 and now it might be a little lower, perhaps 4.7 - these strips aren't accurate enough. I have some higher accuracy ones coming from the UK, it is annoying to have to wait so long. Must buy a pH meter! I will try adding a little sodium hydroxide to lift it to pH 6 and see what happens.
One of the reps is bringing me some Aqua SF-1

to try. I fancy using it to suspend mica in a clear shampoo, to see how that looks.
I might end up going for a blend if I can get a good one. It is getting to be pretty annoying this constant tug of war between pH, viscosity, and shampoo strength.

A pH meter is the way to go. I find the strips are ok, but they are not as accurate. I hope that the sodium hydroxide works out for you.

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Irena
Closed minds are like faulty parachutes; they refuse to open.

I added a little KOH to the shampoo, enough to move the pH up to 6. Viscosity increased a lot; it is now where it should be.
I'm thinking that maybe it is best to mix the surfactants the day before and then add the rest of the ingredients the following day together with final pH adjustment.

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Irena
Closed minds are like faulty parachutes; they refuse to open.