Using Wet Wood
Q. I’m building outdoor furniture from rough cedar. When I
cut the wood, it’s soaking wet on the inside. Should I use polyurethane
glue since it’s a moisture-cure glue?
A. Not when the wood is that wet. Polyurethane glue uses
moisture to cure, but too much moisture will cause the glue to cure
before it gets a chance to soak into the wood fibers and create a
bond. You need to get the moisture content (MC) near the surface of
the wood down to 10 to 25 percent before you use polyurethane glue (6
to 15 percent if you use a water-based Type II or Type III glue). Rough
cedar from the lumberyard is often very wet, but it loses that water
rapidly. The best thing to do is cut your lumber into rough sizes and
then stack the wood indoors with stickers between each board so all
four surfaces of each board are exposed to the air. Cedar dries
rapidly; leave it for a week or two and you should be good to glue.