Description: BULLSUR SB – 21 is solvent based low viscosity two component epoxy primer product based on epoxy (resin) and reactor (hardener) to be used with self smoothing epoxy screed for internal use where surfaces are very porous. More than one coat of primer may be required to achieve the desired bonding efficiency with floor system or other cementitious subtracts. If the substrates are of particularly smooth surface, BULLSUR SB – 21 should be seeded with fine aggregate immediately after application of the primer to give a mechanical key to facilitate installation of resin screeds and topping.