What Surfaces Does Polyester Resin Not Stick To?

Polyester resin, a popular material in various applications, has specific characteristics that can affect its adhesion to different surfaces. Understanding these characteristics can help you ensure successful bonding and adhere to proper surface preparation techniques. In this article, we will explore the surfaces that polyester resin typically does not stick to, including non-porous materials, waxed or oily surfaces, silicone, Teflon, old paints or finishes, certain types of foam, and wax.

Non-Porous Surfaces

Smooth non-porous materials like glass, metal, and certain plastics such as polyethylene and polypropylene can inhibit the adhesion of polyester resin. These surfaces do not allow the resin to penetrate and form a strong bond.

Waxed or Oily Surfaces

Surfaces that have been treated with wax, oil, or other lubricants will prevent the resin from bonding effectively. Waxes and oils create a barrier between the resin and the substrate, hindering adhesion.

Silicone and Teflon

Materials such as silicone and Teflon are non-stick and are often used as mold release agents. These materials are particularly problematic for polyester resin, as they repel the resin and prevent effective bonding.

Old Paints or Finishes

Surfaces with aged or incompatible paint can also lead to adhesion problems. Resin may not penetrate well into old or incompatible finishes, resulting in poor adhesion.

Certain Types of Foam

Some closed-cell foams can resist adhesion due to their structure. These foams do not allow the resin to penetrate, thus reducing the chances of a strong bond forming.

To improve adhesion, it is often recommended to prepare the surface by cleaning, sanding, or applying a suitable primer before applying the polyester resin. Proper surface preparation can significantly enhance the bonding process and ensure the successful attachment of polyester resin to the desired surface.

Wax and Polyester Resin

Wax, especially beeswax, is a common release agent used with polyester resin. It effectively prevents the resin from sticking to the surface, making it useful during mold release processes. For instance, in the past, when manufacturing items from fiberglass, the process involved making a master from highly polished metal, creating working molds using many layers of fiberglass, polishing and waxing the inside surface of the mold before each use. A PVA release agent was often used in addition to wax. To lay up the object in the mold, it was allowed to cure before being removed.