A water soluble dicarboxylic acid acts as a mold release agent for salt blocks when it is sprayed as a fine powder into the block press mold box just prior to a charge of salt. The acid has from 6 to 10 carbon atoms; adipic acid is a preferred release agent. The salt block having a layer of the acid on it surface may be used in water softening systems wherein the block sits in a brine reservoir and supplies salt for the recharging of an ion exchange resin. There is no build up of an unsightly scum on the surface of the brine and on the sides of the reservoir as there has been with the use of calcium stearate as the release agent.
