There are three main types of release agents used in manufacturing: internal release agents which are added directly to composite materials, conventional or non-permanent release agents which require reapplication each cycle due to being solvent-based, and semi-permanent release agents which form protective barriers and allow multiple releases without affecting material strength. Semi-permanent release agents are now most commonly used in composite molding as they reduce costs and cycle times compared to other options. Proper selection of a release agent considers its effects on both the composite and mold materials, required level of slip, safety, and desired surface finish of the final product.