Thoroughly clean the bonding and edges of the joints, joints, make sure that there are no residues of oil, grease, wax and silicone. The substrate must be dry, chemically neutral, even, strong, clean - free of dust, rust or flaking particles.
For many surfaces a primer is not required. In the case of application to a very porous surface must be carefully primed to avoid getting air bubbles in the uncured sealant. Recommended primer is SuperTectum Macro Primer.