Epoxies are a family of versatile polymer glues. They can be used to form thin surface bonds, thick structural bonds, or even layers of lamination. Epoxy is commonly sold as two tubes of epoxy resins which must be mixed together.

Epoxy resin is very thick and viscous. I generally use a small square of cardboard as a putty knife in order to apply the stuff. The setting time for epoxy varies depending on what formulation you buy. During the "pot life" period, where the glue is still quite liquid, you can move and shift the items being glued. This makes epoxy very useful for applications where precise alignment is required.

Fiberglass is created by layering woven fiber mats soaked in epoxy. You can make fiberglass by purchasing fiber patches (they sell them specifically for this purpose at hobby shops), lightly covering them with epoxy, and then applying them in layers, much like papier-mache. A stiff-bristled brush can be helpful in applying the fabric layers.

Using Epoxy

Epoxies are commonly sold as two resins which must be mixed before application. Usually the chemicals are balanced so that you need to combine equal amounts by volume of the two components. Epoxy is fairly forgiving about these ratios, so feel free to eyeball it.

I recommend mixing the components in a separate mixing cup before applying them to the surface being glued. This results in more thorough combination of the components, which yields a stronger bond. It is almost impossible to remove epoxy from the mixing/application tool, so I do not recommend using a brush for this purpose. Instead, try using cut pieces of cardboard or wooden tongue depressors.

Epoxy releases strong fumes while being mixed and applied. I don't know that they are demonstrably harmful, but they can be offensive enough that I'd recommend workspace ventillation whenever you are using epoxy.

Epoxy takes one to two days to fully cure; consult the instructions with the specific kit you purchase. When dry, epoxy is rigid, although not overly brittle. For this reason, epoxy doesn't tend to form lasting joins with flexible rubbers, such as latex. For smooth surfaces, it helps to score them with sandpaper to give the glue a better chance at establishing a mechanical grip.