Achieving completely smooth paint finishes takes skill, patience, and attention to detail. The main keys to success are in brush technique and good preparation of the surface you are painting. Perfectly smooth finishes also depend on the type of paint used. Wood surfaces can present some of the biggest preparation challenges, but much of the labor involved is relatively simple. The following are some tips to help with the best approach to a smooth paint finish.
Remove Old Paint and Clean Wood
A wood surface that has chips, scratches, peeling paint, or cracks will not make for a smooth coat of paint, and the paint will not camouflage any of these defects either. Start by using a putty knife to carefully lift and remove any loose paint; it helps to move the putty knife in more than one direction. Once all of the old paint has been removed, clean the surface with a tri-sodium phosphate (TSP) cleaning solution meant to be used on wood; this will remove any remaining grime and debris within the wood grain. These solutions need to be mixed according to their included directions, and be sure to rinse away all traces of the TSP with clean water and give the wood surface plenty of time to dry.
Apply Filler Resin
Once you have removed all of the old paint, look for any scratches or dents larger than about 1/8 inch. These will need to be filled with a polyester based wood resin. This resin comes with a separate hardening compound that will need to be mixed according to manufacturer's directions. To do this, scoop out an amount of resin roughly the size of a golf ball, and mix it with the hardener on a scrap piece of wood. Apply this resin mixture to your wood surface quickly and evenly because it only takes about 5 minutes to start curing.
Apply Spackling Compound
For smaller and finer scratches in the wood, cover these with spackling compound. Use a heavier spackling compound rather than a lightweight one because those are not quite as effective.
Sand Wood Surface
Once you have applied all needed filler and spackling, rub the entire wood surface with 180-grit sandpaper to even everything out. Be sure to thoroughly wipe away any sanding dust with a damp rag; the last thing you want is to have these kinds of dust particles stuck in a new coat of paint.
Use the Best Paint and Brushes
After you have invested the time and labor in surface preparation, you want to use good quality paint and brushes to ensure a smooth finish. Latex-based paints are used the most often due to how quickly they dry and how easy spills are to clean up. One of these advantages to latex is also a drawback; faster-drying paint does not have the time to settle and flatten as much as oil-based paints. There are now additive compounds developed for latex paint that solve this problem by slowing down the drying process. A latex additive allows the paint to lay more smoothly by the time it dries.
When it comes to brush technique, a common mistake is to dip the brush directly in the paint can. Pour about 1 quart of paint into a 4-quart plastic bucket and then add the amount of additive according to a 1 quart ratio that should be included in the additive instructions. This is both easy to carry and easy to wipe the brush on the bucket sides to avoid drips.