Bare plaster or concrete are highly absorbent materials which tend to soak up the first coat of paint. Therefore, a primer should be used to seal the surface and provide a smoother profile for painting. Gunzite primer should only be used as a base coat for Poxolon or Zeron. Do not use epoxy primers in conjunction with rubber base paints. Gunzite is a two part epoxy primer for application over unusually rough plaster or concrete. The heavy viscosity of Gunzite acts as a fill coat on these surfaces and provides a much smoother surface. Gunzite should only be used as an undercoat for Poxolon or Zeron. Especially effective on sandblasted surfaces.