11 Tips on How to Finish Wood Trim
Get top-quality results with these tips from an experienced pro.
Sand Wood for Even Finishes
The trim you bought may look perfect, but it likely has imperfections from machining that won’t show up until you stain it. Sand every contour and flat area in the direction of the grain with a combination of medium-grit sanding sponges and pads. When necessary, fold 120-grit paper to get into tight cracks.
Test Stain Colors First
Try out the stain on a sample of the same wood you plan to finish. You can create your own custom color by mixing two or three stains (of the same type) together. If you go this route, it’s important to mix up a batch big enough to finish all the wood. The odds of achieving identical results on the second batch are slim. Keep a little extra on hand for touch-ups and repairs.
Stain One Piece at a Time
Saturate the wood with a liberal coat of stain using a natural-bristle brush. Wipe off the stain with clean cotton rags in the same order you put it on. That will enable the stain to soak into all areas of the wood for about the same amount of time. Wipe with light, even pressure. Refold the wiping rags frequently so you have a dry cloth for most of the strokes, and grab a new rag whenever one gets soaked. Work on one piece of trim at a time to keep the stain from drying before wiping.
Apply Sanding Sealer First
Long Strokes = a Smooth Finish
If you can, arrange your trim boards in such a way that after you brush on the desired amount of finish, you can make your last couple strokes in one continuous pass. That will ensure no overlap marks. If you do end up with imperfections after the finish dries, sand them out when you sand before the next coat.
Clean the Room
If possible, do your sanding and finishing in different rooms. All that sanding dust will affect the clear coats. If you have to sand and finish in the same area, do whatever you can to clean the room before applying the sanding sealer and clear coat. If you’re in a garage, open the overhead door and use a leaf blower to blow dust outside. Use a shop vacuum on the floor, and damp-mop it so your feet don’t stir up dust.
Don’t Skimp on the Brush
Oil vs. Water-Based Topcoats
Polyurethane vs. Varnish
What’s the difference between polyurethane and varnish? The quick-and-dirty answer: Varnish contains a resin and a solvent (oil or water). Once varnish is applied to wood, the solvent evaporates and the protective resin is left behind. Varnish can contain one of a few different resins, and polyurethane is one of them. Varnish that contains polyurethane just goes by the name polyurethane. The upside to polyurethane is that it’s tougher (like a plastic coating) than the other varnishes. The downside is that it can appear cloudy when it’s applied too thick, and it’s harder to sand between coats.