This standard specifies a method for the determination of the solubility of ionic surface active agents in water as a function of concentration and temperature and for the determination of the Krafft point by graphical evaluation of the measurement results. In the temperature range from 0°C to 90 °C, the solubility is determined without any limitations if the viscosity of the solution does not exceed about 700 mPas. At temperatures below 0°C, determination is only possible if the solvent does not freeze. The method is applicable both to pure surface active agents and to technical products optically clear and not unduly coloured solutions. The solubility bot