Are all stain blocking primers made equal?
When dealing with old stains or discoloured surfaces, a standard undercoat often fails to cover problem areas. A dedicated stain-blocking primer is essential. We compared four leading water-based options – Ronseal One Coat Stain Block, Dulux Trade Aqua Uni Primer, Crown Trade PX4, and Zinsser Bulls Eye 1-2-3. Following a light sanding and a single coat application, one primer outperformed the others in terms of opacity and coverage. Watch to discover which product delivers the best base for a flawless top coat.