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Q I bought an unfinished coffee table and am wondering what type of clear wood finish you recommend. I would
like an unstained, natural wood look.
A Table surfaces in general take a lot of abuse, so they need to be protected with a durable finish. If your coffee table is like mine, it serves multiple duty as an eating surface, a footstool (till I get yelled at) and a home for things like metal candleholders, vases, toy trucks and other scratchproducing stuff. The toughest finish you can apply without an industrial setup is polyurethane (poly) varnish.
Polyurethane combines alkyd resins with polyurethane plastic and additives to help it dry and cure to a bulletproof plastic barrier. Poly comes in two basic varieties: oil, and my choice for your project, water-based.
Water-based poly has several advantages over oil-based:
It has less “open time” (dries faster), so dust will have less time to fall onto and stick to the finish. Less open time means fewer surface flaws and the ability to apply multiple coats on the same day.
Water-based poly is “self-leveling,” so brush marks will settle out, producing a flat, smooth surface.
Water-based poly is nearly odorless. Oil-based poly just plain stinks for hours during curing; wear a respirator and provide good ventilation during application.
You can clean up water-based-poly tools and containers with water and mild soap. Oil-based messes need to be cleaned up with paint thinner.
Raise the grain, then sand before applying finish
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1. Water-based poly raises the grain, so you should first dampen the surface with a moist sponjge. After it dries, lightly sand the standing grain with 220-grit sandpaper. Oilbased poly doesn’t require this step.
For deeper tones, tint raw wood with shellac first
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2. Water-based poly has a flatter, colorless finish while oil-based poly gives an amber, deeper hue. One option is to apply a base coat of shellac (wax free) or stain, or add a water-based dye to the water-based poly to enhance the wood’s character.
Use foam or synthetic brushes
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3.Use only foam or synthetic brushes or a paint pad applicator. Natural bristle brushes work fine in oil-based poly, but in water-based poly the bristles soak up water and lose their stiffness. Plan on three coats for the most durable finish, sanding between coats with 220-grit sandpaper.
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