Do I need a primer before painting concrete?

Why concrete needs a primer

Concrete is naturally porous, and different areas of the same slab can absorb coatings at different rates. Without a primer, paint or resin can sink in unevenly, which often shows as patchy sheen or colour. Priming helps seal the surface so the topcoat cures more evenly and stays bonded for longer. “Epoxyprimer” is formulated for this job on concrete, timber, screed and ceramic tiles, and can be applied by roller, brush or spatula.

• Improves bond between the concrete and the final coat
• Reduces uneven absorption and patchy finish
• Helps create a uniform base for a more consistent colour

When a primer matters most

Priming becomes more important on bare or highly absorbent concrete, older floors that show dusting or friable patches, and any floor that will carry regular traffic. In high-traffic or driveable areas, pairing a primer with a durable topcoat such as “Prolux” PU coating is often a better route than painting directly onto bare concrete.

If the concrete is very dense or has already been sealed, a primer can still improve adhesion, but the benefit is usually less dramatic. Check the product data and surface condition before deciding whether to skip it.

Primer and coverage on a 33 m² concrete floor

For a 33 m² concrete floor, primer coverage depends on how porous the slab is. The Epoxyprimer system has a suggested consumption of 100–300 g per m², so the total could range from roughly 3.3 kg to 9.9 kg depending on surface absorbency. That makes the primer a meaningful part of overall material planning when you are calculating how much paint or coating to buy for the same area.

A one-component concrete sealer like “Resinstone” is formulated for sealing and protecting concrete floors, but if you are using a separate paint or resin system, a primer is still the most reliable way to prepare the surface.