How to Prime Old Concrete Before Repainting
Older concrete often contains contaminants, laitance and microcracks that prevent coatings from bonding correctly. Start by mechanically preparing the surface using a grinder or shot blaster to achieve an even profile. Remove all dust and wash away oils or chemical residues. Choose a moisture tolerant or penetration primer depending on how worn the concrete is. Apply the primer evenly and allow full curing before the main coating. This creates a stable, long lasting base.