I'm working on a household cleaning product. It is an acidic one with pH below 4.
At a pH about 4,3 I have a clear liquid with a viscosity of water. When I lower the pH my clear liquid becomes more viscous (pH 4,2 - 3,9). At a pH 3,7 the solution becomes cloudy and a sediment starts to appear... So my solution is unstable.
I made some more tests.
When I have no preseravites (only water, sodium cocoamphoacetate and citric acid) the problem doesn't occur - I can drop the pH even below 3 and there is no viscosity changes or sediment.
When I use only sodium benzoate the problem occurs in lower pH (about 3,2).
When I use preservatives and switch cocoamphoacetate to CAPB the phenomenon does NOT appear. Only with cocoamphoacetate.
Can anyone explain what is happening?