I have been working on a new fireplace mantel for my living room. The finish needs to be tough, so I chose to use polyurethane. Previous to this, I had used spray-on finishes on my projects, but went with liquid this time around. It took a bit of experimentation before I hit on a technique which works well for applying the finish.
The wood is red oak. The stain is Minwax, Wood Finish, Early American. The finish is Minwax, Fast Drying Polyurethane, Clear Semi-Gloss.
My first attempts were to brush on the poly. After reading posts on this board, I tried applying the poly both fast and slow, but no matter how careful I was, I kept getting bubbles in the finish. Then, between coats there was a messy, time consuming brush cleaning stage. I quickly realized that between sanding out bubbles between coats and cleaning brushes, finishing all these parts was going to take forever.
Note that whenever I open either stain or finish I wear disposable gloves and a respirator. All stain and finish is applied using 3"x3" pieces of fabric cut from an old, soft T-shirt. This is folded into a pad which has the "grain" of the fabric perpendicular to the direction I'm wiping, to prevent streaks. When finished, the pad is unfolded and hung on the inside of my waste basket to dry before disposal.
Here is the technique I finally landed on:
- Using a Bosch ROS, sand with 150 grit, then 300 grit sanding disks.
- Wipe boards with piece of old T-shirt, slightly moistened, to take off sanding dust.
- Use a T-shirt pad to quickly apply stain to the wood, then even it out with long, slow, overlapping strokes, with the grain.
- Let the stain dry for 10-15 minutes, then rub off excess with another clean T-shirt rag. If the wood has worm holes and other irregularities that hold liquid stain, check it and dry wipe it again in another 30 minutes or so. This keeps stain from bleeding out of the holes and making dark blotches around the holes.
- Let dry overnight.
- Stir the polyurethane with a stirring stick. Let the stick drip back into the can, and wipe off stick with fresh T-shirt pad.
- Use the pad to transfer polyurethane onto the surface of the board, using slightly diagonal strokes, until the entire surface is wetted.
- Use long, quick strokes to even out the poly on the face of the board. Go around the edges to catch any runs.
- Finish up by making long, slow, light, overlapping strokes. These strokes establish the surface finish and eliminate any bubbles. Check the reflection of the board to be sure there are no bubbles or streaks.
- Let polyurethane dry for at least 8 hours.
- Using a 300 grit ROS sanding disk wrapped around a wooden sanding block, very lightly sand the surface of the finish to knock off the little bits of roughness which occur. This roughness will be the worst on the first coat. After the wood is sealed, subsequent coats become progressively smoother.
- Wipe off sanding dust with a dry T-shirt rag.
- Repeat poly application and sanding for a total of 3 to 4 coats. Don't sand after the last coat.
- Finish up with 2 or 3 coats of Johnson's Paste Wax.
This finishing process is a weekend project in and of itself. I make sure the wood is sanded and wiped down ahead of time. Stain the boards Friday night. The first polyurethane coat goes on Saturday morning, the second after dinner Saturday night. The third and fourth coats go on Sunday morning and evening. The entire process consumes about 1/3 to 1/2 of an old T-shirt. Also, while the finish is drying, keep out of the shop, to avoid raising dust into the air.
I know this post was a bit wordy, but hopefully it will help some others avoid the frustration I started out with. The key is to keep the polyurethane coats thin and use an applicator which is not inherently "bubbly". I was ready to give up on brushed polyurethane, but using this technique gives fantastic results with a minimum of cleanup time.
cheers,
Todd F.
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