Painting Tips - Painting Wood April 3, 2007
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I receive a lot of questions about painting wooden surfaces. Actually, if you appreciate wood, my advice is to go with varnish, rather than paint. A varnish
is a transparent clear protective coat which may be either glossy or matt. It also comes in tinted range, giving the wood a colour while protecting it. As varnishes are transparent, the wood grain patterns are not concealed. It is this that gives the wood its beauty. Each piece is different as nature and time carves out unique patterns on different types and different cuts of wood. A fewtypes of wood grain pattern are shown below:
A good product to use, especially on exterior wooden surfaces is the ICI Solarscreen (see post). For indoors, you can use the Nippon Timberlac (see fig. on the right) which comes in Clear Gloss and Clear Matt plus 6 other colours (see chart pg 18). However, if you still insist on paint, let me discuss the processes on 1) bare unpainted wood and 2) on previously painted wood.
i) Painting on a bare unpainted wooden surface If you go for paint, sand the surface with a 280 - 320 grit wet-or-dry sandpaper. This will smoothen the surface further for a better finish. Remove sand particles and this is best done with a lint-free cloth lightly wetted with paint thinner. The 
wetness of the cloth picks up the sands and the thinner vaporizes almost immediately. Put 1 coat of white alkyd undercoat (left) and allow about 2-3 hours drying time. A good alkyd undercoat to use is the Nippon Bodelac 90 Undercoat or the Zinsser Bullseye 123 (see previous post). If the wood you are painting is constantly exposed to moisture, a great primer to use is the Aluminium Wood Primer. The aluminium powder in the primer fills up pores and cavities in the wood, reducing entry of water. After the primer, topcoat with 2 coats of alkyd enamel. Nippon Bodelac Alkyd Enamel is a good topcoat to use and is available in a wide range of colours (see Colour Chart pg 14, 15).
ii) Re-painting
If the existing paint is peeling, use a 1.5 inch or 2 inch metal scraper to remove the loose paint. Smoothen surface with a 180 grit wet-or-dry sandpaper. If the existing paint work is intact, you would still need to prepare the surface. This is where most
make the mistake and assume a direct overcoat of the new paint would suffice. It is not true. A direct coat of paint will not adhere properly onto the old coat of paint as the substrate usually lacks profile. We need to create profile and improve adhesion either by sanding or by applying 1 coat of undercoat, or best of all, both. Use 280 grit sandpaper to sand down. Remember that we are not trying to remove the old coat, but simply trying to create surface profile. After the sand down, remove the loose sand particles using paint thinner on a wet cloth. If time is lacking, or if energy is lacking, you can apply the topcoat right after sanding down. If you have a bit more time (and enthusiasm), paint 1 coat of white alkyd undercoat before the topcoat. I will discuss varnishing in future post. The salient point in this post is that the surface needs to be prepared even if the old paint is intact. Paint overcoats poorly onto old alkyd paint, especially the glossy ones.
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