A The Krafft Point

If the CMC exceeds the solubility of the surfactant at a particular temperature, then the minimum surface tension will be achieved at the point of maximum 

For surfactants that are being used above Tk, maximum reduction, for all practical purposes, is reached at the CMC. Since surfactants are normally used above their Krafft points, we restrict our discussion to that condition and consider maximum surface tension reduction to occur at the CMC. 

---