Blocking

Causes

• Pressing newly painted surfaces together before they have fully dried
• Using slow-drying, oil-based paints that have been stored for long periods
• Applying another coat of paint before the first coat is completely dry Applying excessive amounts of paint on a surface
• Using a low-quality, water-based semi-gloss or gloss paint not designed to have block resistance

Solutions

• If the area has never been painted, prime the surface with a high-quality primer.
• If a blocking condition already exists, scrape or sand the surface to remove all loose paint. Clean off any dust or dirt and then prime the area with a high-quality primer.
• Doors and windows should be properly adjusted for free and smooth operation before painting.
• Use a top quality semi-gloss or gloss acrylic latex paint. Low-quality latex paints generally have poor block resistance, especially in warm, damp conditions. Acrylic latex paints generally have better block resistance than vinyl acrylic paints or alkyd and oil-based coatings. Alkyds, however, can develop superior block resistance as the film hardens.