Q: I have just replaced a support pillar with a new piece of 6-by-6 Douglas fir. It is bleeding pitch, or resin, on two sides. I plan to prime and paint it when the weather improves.
How best can I remove the pitch and reduce the chance of the pitch reappearing after I paint? How long should I wait before tackling this job?
A: To get a good-looking, long-lasting paint job, you need to wait for the wood to adjust to its new environment.
The lumber you bought is probably construction-grade fir. This lumber grade is used for its strength, not its looks. It’s the stuff houses are framed with. But when properly prepped and painted, construction-grade lumber can look good.
Construction-grade fir is greener lumber, with a higher moisture content than its kiln-dried counterpart. Kiln-dried fir is selected for the absence of imperfections and heat-dried in a kiln at the lumber mill.
Certain imperfections are allowed in construction-grade boards, provided they do not compromise structural integrity. These imperfections, cracks and checks are producing the pitch.
The positive side is cost. We know the 6-by-6 post you bought cost you a whole lot less than the same model in kiln-dried, straight-grain Douglas fir.
To get the best paint job, our first caution is to be patient. Since we’ve had a pretty wet winter, don’t tackle this project at least until after the Fourth of July. This will give the moisture time to stabilize and allow most, if not all, of the pitch to run from the wood.
Start the paint job by scraping any dried pitch off the post with a sharp paint scraper. Next, give the post a good wipe down with a rag soaked in acetone or lacquer thinner. This step will help remove any pitch left after scraping and won’t raise the grain of the wood.
After wiping, thoroughly sand the post. A handheld orbital sander works well. Vacuum or tack the sanding dust off the post, and you’re ready to paint.
We suggest two coats of primer followed by two coats of latex or acrylic finish paint.
Since this particular piece of wood is prone to releasing its pitch, we’d start with a stain-blocking primer, such as Kilz.
Two coats of Kilz should act as a sufficient stain blocker, provided you’ve waited long enough for the moisture content in the wood to settle.
Allow a day between application of the primer coats, to let each coat dry thoroughly.
Lightly sand the post between primer coats in order to provide a smooth base for the next coat. Finally, apply two coats of an acrylic or latex paint. Don’t sand between coats, as freshly applied acrylic does not sand very well, and you risk marring the finish.
If you wait until summertime and follow these steps for painting, your replacement post will look as if it was always a part of your house.