Hobbies And Interests
Spray Resin or Gelcoat
In the beginning of the fiberglass process, gelcoat is often sprayed onto the fiberglass mold after a release agent has been applied. Gelcoat is polyester resin. Color and other additives, such as UV protection, are sometimes added to gelcoat as the first coat of polyester resin sprayed into a mold becomes the exterior of whatever's being molded, such as a boat's hull.
Brush On
Brushing polyester resin onto fiberglass mesh with a sponge brush or bristle brush is a common technique, even in industrial applications. This is one of the techniques referred to as "hand laid." Typically, mesh will be laid out -- often over an initial layer of gelcoat -- then liquid fiberglass is generously painted on, soaking through the mesh. This application process isn't about being tidy, but evenly saturating the mesh.
Pour and Roll
The pour and roll technique is similar to brushing resin on and is sometimes used in conjunction with brush techniques. Liquid resin is typically held in a plastic measure and mixing tub. Some of the resin is poured onto the fiberglass mesh, then it is evened, not with a brush, but a roller. Some rollers are very similar in design to paint rollers, but some are much smaller with less nap. Rollers accomplish the same job as brushes, but they are more effective at distributing the resin and working air bubbles out of the mold.
Spray with Fiber
For larger scale or higher production industrial jobs, glass fiber along with liquid polymer can be shot from a gun similar to liquid insulation or gunite, which is liquid concrete. This is a special spray rig made specifically for fiberglass. Once gelcoat is sprayed, a liquid/fiber blend may be sprayed to give the shape the bulk of its strength.