The amount of resin needed to wet out fiberglass cloth depends on the weight of the cloth.
The following are general estimates for epoxy coverage when wetting out some common types of fiberglass material. Note that these estimates are based on wetting out one layer**.
- 4 oz. fiberglass cloth - One gallon of mixed epoxy wets out approximately 37.5 square yards
- 6 oz. fiberglass cloth - One gallon of mixed epoxy wets out approximately 25 square yards
- 10 oz. fiberglass cloth - One gallon of mixed epoxy wets out approximately 15 square yards
- 1708 biaxial fiberglass cloth with mat backing (23.75 oz. per square yard) - One gallon of mixed epoxy wets out approximately 6.4 square yards
- Fiberglass CSM (chopped strand mat) - One gallon of mixed epoxy wets out approximately 5 square yards
- Fiberglass 18 oz. woven roving - One gallon of mixed epoxy wets out 4.5 square yards
- Fiberglass 24 oz. woven roving - One gallon of mixed epoxy wets out 3.5 square yards
** This number only represents how much epoxy is required to wet out a specific fiber, and does not account for any extra epoxy that is applied to a substrate before wetting out the epoxy, or epoxy used between layers of fabric. Conservatively, consider that 15-20% will be lost to waste material in the mixing cup, any extra drips, brushes used for application, and epoxy left on rollers, spreaders, or other tools.