What is cloud point?
The cloud point is the temperature at which a non-ionic surfactant becomes insoluble and the solution turns hazy. Above it the surfactant stops stabilising foam, which is exactly why low-foam cleaners are formulated to cloud below their working temperature — around 45–55 °C for a 55–65 °C wash.
Below the cloud point the surfactant is fully dissolved and behaves as a good foamer. Above it, it partially separates, the foam film loses its stabiliser and collapses. Formulators use this deliberately: pick the surfactant so the cloud point sits just below the intended bath temperature and the cleaner is self-defoaming in service.
The practical consequence is that a low-foam cleaner run cold is not low-foam. A spray washer started from ambient will foam for the first ten minutes and settle once the bath reaches temperature. If it never reaches temperature, it never settles.
Cleaning power also peaks near the cloud point, because the partially-separated surfactant concentrates at the oil-water interface. Running the bath in its designed window is therefore both a foam decision and a performance decision.
