I will give it a try Michael,
Are the bumps small craters, likely the remnants of bubbles breaking the
surface and then drying as they burst? If so I would add some solvent to extend
the drying time and switch to using a rag with the diluted poly if this does
not work. Light coats are almost always best. Sometimes the material can start
to polymerize in the can forming small crystals which you need to filter out or
buy a can from a different batch. Cheers, JG


Michael White wrote:

Hi all,

I'm trying to put a polyurethane coat onto a bookcase I'm building. Since
it's a prototype, it's made out of cheap, soft pine. I've got it stained,
and I'm trying to put on the final coat of polyurethane. But I keep
getting small bumps about 1 mm in diameter in the polyurethane coat. If I
sand them down and put on another coat, they come back (although I'm not
sure if they're in the same spot).

This seems to occur no matter how thick or thin I put the polyurethane on.
When I apply it, I've tried both not dragging the brush across the rim of
the can and just knocking off the excess. I wipe down the surface after
sanding.

I think I've got about five or six coats of varying thickness trying to get
rid of these bumps. What the heck am I doing wrong?

Thanks in advance.
--
Michael White "To protect people from the effects of folly is to
fill the world with fools." -Herbert Spencer, 1891