I have a problem with a detergence formula that has a non ionic surfactant and an optical brightener. The problem is that when we are heating the solution until 40ºC to solve the optical brightener (solid) the transmittance worsen with the temperature. I have read about the cloud point, specially with non ionic surfactants. Any idea how to prove that this is the phenomenon that the solution is going through? I tried to raised the temperature a lot to see if phases separate but nothing happens. And if this would be the case, how can i change the could point of a solution ? THanks !