Why am I getting tiny pinholes in the paint film during the application?
Pinholing in plaster surfaces is normally due to overpainting a very porous surface (either the plaster or a filler) without adequately thinning the priming coat. To remedy, repaint with two thinned coats.
Why does paint begin peeling away from a surface in sheets?
Like flaking, peeling results from paint losing its adhesion properties. Often caused by applying thick coatings to poorly prepared surfaces, e.g. unthinned emulsion onto distemper. The cure is to thoroughly scrape back all areas of poorly adhering or defective coatings to a firm edge. Finally, rub down to "feather" broken edges, dust off and repaint.
How can I remedy sags and runs on new paintwork?
This is usually caused by uneven paint application on broad, flat surfaces, or by over-applying on mouldings or rough-contoured surfaces. Also, failing to join up "wet edges" before they have set can cause excessive film thickness, resulting in sagging and running. When the paint film is thoroughly dry rub down the sags/runs using wet and dry abrasive paper (or waterproof silicon carbide) together with warm water and detergent. To prevent sags/runs when painting broad, flat areas, work systematically and cross-brush each section into the next; finally using vertical strokes to gently lay off along the length of the surface.
Bubbles on the paint surface have appeared after using a foam roller. How can I correct this?
Foam rollers should not be used with water based paints. If you already have this problem there are two solutions.
- Line with lining paper and repaint
- Rub down smooth and repaint
I get a foaming and frothing effect when using a roller. What causes it?
You're using the wrong type of roller. For instance, if you use a sponge roller to apply water-based paints, air is injected into the wet paint film and the air bubbles burst, forming craters on the surface which dry unevenly. As a rule of thumb, use short pile rollers for flat surfaces, medium pile rollers for medium textures and long pile rollers for textured surfaces. After rolling, some paints, particularly solvent-based gloss, may need to be "layed-off" with a brush to eliminate foaming. To repair a foamy surface, thoroughly clean it down to remove all dirt, grease and surface contaminants. Rub down the surfaces with wet and dry abrasion and water or a suitable solvent. Finally, rinse down and allow to dry thoroughly before repainting. If this is impractical, line the walls before repainting.