Poly and the Pine Knot

[Chuck Jones]

Did I do something really dumb spraying poly on this piece of white pine? Four or five days later the knots are still tacky. The rest seems okay, but not the knots.

I picked up some white pine logs while my volunteer team was cleaning up after the ice storm in KY back in February/March. I was intrigued by the radial pattern of the limbs. I turned a piece of it green (and spent the next two months cleaning the gum off my tools and shop floor).

After the piece dried and I tried to finish turn it I wasn't particularly happy with it. I haven't gotten around to taking "Finishing 101" yet and I haven't used much polyurethane. Thought this might be a good piece to experiment with so I just grabbed a can of poly and gave it a try.

[Michael Pyron]

it can take over a year to air dry woods....so that piece is still sopping wet...

I'm thinking the resins in the knot are reacting with the poly and preventing it from drying...

[Conrad Fiore]

Chuck,
In order for the pitch to set in pine, the wood must be kiln dried at 160 deg. Otherwise the pitch will continue to "leak" out of the wood. Or you could seal the knots with shellac.

[Howard Acheson]

You can try coating the surface first with shellac. Shellac is frequently useful in sealing the pitch which is affecting the drying of an oil based finish. Remember, turpentine is made from pine sap and pitch.

Another point, as the pine dries, knots can become lose and fall out.

[Chuck Jones]

What you guys are saying about the pitch makes sense. That must be the problem. It was not kiln dried, but it has been in my (usually) heated shop for a couple months and dried more than you might think. It registers 9%-10% on my moisture meter, but because it's round that's probably not a good reading. Anyway, I'm going to put it back for a few years and forget about it. Got plenty other wood to turn.

[glenn bradley]

+1 on shellac for a sealer.