A release agent is a chemical, typically a liquid, used to facilitate the easy removal of molded or cast parts from the molds. These chemicals are applied to the contact surfaces of the mold prior to casting or molding, preventing excessive adhesion between it and the finished part. This effect is achieved by forming a second surface or a barrier layer between the mold surface and the part, which is then later removed from the finished product. These agents are typically based on silicone, oils or soapy surfactants with several special food-grade formulations utilized in the food processing industry. Release agents are widely used in a variety of applications, which include concrete casting, plastic molding, fiberglass molding and paper making.
Removing cast or molded parts from their forms may sound like a fairly simple process but can, at times, present some fairly sticky problems. This is particularly true of complex parts which often require considerable amounts of effort to dislodge from the mold. The use of a release agent greatly reduces the amount of time and effort expended on this task by simply providing a second internal surface between the mold and the product. In some cases, this second skin or film will simply lubricate the contact surface between mold and product and in others provide a physical film or skin, which allows no product adhesion at all. Other release agent types react chemically with the product, thereby preventing adhesion.
Release agents may be liquid solutions applied with a spray gun or paint brush, wax compounds applied with a cloth or convenient aerosol types. The active components in low-viscosity liquid release agents are typically suspended in various solvents, some of which could pose health or environmental hazards. This should be kept in mind when working with or disposing of these products. In addition, as with all solvents, the maintenance of adequate ventilation and fire prevention should also be considered.
Although release agents make removing molded and cast parts easy, they often have a significant effect on the surface texture of the finished product and may prevent the application of post-production finishes such as dyes and paint. The correct choice of release agent is, thus, fairly important if reject rates are to be kept at a minimum. This choice is fairly easy to make considering the extensive range of agents available. The fact that the product is often subject to considerable release agent contamination should also be kept in mind where sensitive parts meant for the pharmaceutical or food industries are being produced.