In The Swim Gunite Primer is a two-part epoxy primer typically used on fiberglass gel-coat, rough plaster, rough concrete, or sandblasted surfaces. Gunite Primer’s heavy viscosity fills imperfections on the interior surface give a more uniform look. Gunite Primer should be rolled on with a paint roller. Coverage: Approximately 100-150 square feet per gallon. Should be applied liberally using a 1/2″ nap roller cover.