Three coat paint systems - typically one coat sealer followed by two top
coats is the minimum specification recommended.
Preparation & Application
The following comments should be taken as a guide for the preparation and paintings of plasterboard.
- All surfaces should be clean and dusted down prior to painting.
- First coat should be a recommended plasterboard sealer rolled or
sprayed - lightly sand when dry.
- Apply two top coats (undiluted) - paint with brush, roller or spray (back
rolled).
- It has been a long-standing recommendation of plasterboard
manufacturers, that roller application of paints is preferred as the light
dimpling imparted by the roller gives greatest obscuration of surface
characteristics.
Gloss Paints
Gloss paints and even semi-gloss paint on flat surfaces reflect light in a pattern distorted by the imperfections of the surface. This effect is enhanced as the observer moves around the room. Flat paints on the other hand tend to reflect light back in a diffused form which does not draw the attention of the observer to surface undulations or imperfections.
It should be pointed out that plasterboard is a machine made product with a textured paper surface and that the jointing is a hand applied operation. When sanded the two different surfaces are evident and for this reason - gloss paints should be avoided where possible.
It should be emphasised that in some cases gloss paints may be desirable for purely functional reasons, e.g. kitchens, bathrooms, etc. In which case some loss of appearance will have to be accepted. Even when the work has been carried out by the most highly skilled tradesmen, the end result can be most disappointing when gloss paints are used for decorating purposes.
Spraying Paint
Contrary to popular belief, the spray method of painting has not been recommended for the painting of plasterboard and has gained a bad reputation through over-dilution of paint, poor tradesmanship and reluctance to back roll the freshly applied surface.
The spray method of painting aggravates face paper napping and
highlights joint lines.
Spray application does not assist in equalising the surface of what is
basically two completely different materials. (Paper faced plasterboard
and porous joint compound).
It is a fact that a good plastering job can be made to look quite ordinary by poor painting practices.
If spray painting is to be used, the following steps are recommended:
- Prepare as for other applications.
- Apply seal coat and wipe over joint lines and adjacent board with fine
sandpaper when dry.
- Spray first top coat and back roll with a dry roller immediately behind the
spray gun.
- Spray final coat and back roll if required - i.e. if joints are still visible.
- Use premium quality paints only.
- Do not dilute beyond manufacturers recommendations.