Removing cloudy stain on Polyurethane finish

[Philip Florio]

Hi,

I made a small desk piece, the Polyurethane I used was Minwax Oil Clear Satin.

I put on 2 coats over stain. After the base was dry I needed to reapply the polyurethane to one of the attached pieces. I used a foam brush and got some of the polyurethane on the base, I wiped it up using the dry part of the brush. However this has caused a cloudy milky stain.

Minwax recommended using 220 grit paper followed by Mineral Spirits, I was told this wouldn't remove the finish. Would anyone recommend this or have a better solution. I think I'll try first with some steel wool.

Thanks,
Phil

[Cliff Rohrabacher]

I'd do the steel wool too.

I have never gotten cloudy alkyd urethane other than the one time back before I knew anything at all and I re-finished my first hand-made guitar. It was a copy of a Martin 12 I had repaired for a guy. I had prior finished m,y guitar with shellac and found that in the summer the shellac wasn't optimal. I wanted something that wouldn't get ruined by my sweat.
within a year or applying the urethane the whole thing clouded over because of wax in the shellac. Sanding that thing out was a real pain.

[Howard Acheson]

If I understand what you have said, you have created the cloudy stain by getting varnish on an already finished surface. When you then wiped it off, you did not get it all off. Some remained and dried on the surface.

The best way to deal with it is to let the surface fully cure for 2-3 weeks and then sand the complete surface with 320 paper. Mount your paper on a flat sanding block and sand with the grain. Then apply another coat of finish.

[Prashun Patel]

This can happen with satin clear finishes (alkyd or poly). Satin finishes have silica particles to obscure the sheen. These are emulsified into the varnish. They settle quickly. That's why you have to mix satin finishes extremely well, and constantly during use.

You can usually remove them by using a clean rag and mineral spirits. You might have to wipe, let dry, then rewipe a few times to make sure it's ALL off.

I've also found thru experimentation that the 2nd coat often clears up the 1st coat; the 2nd coat removed all the clouding, blotching and all but the worst white spots fm the 1st coat.

You gotta keep mixing thru application, though.

Cliff, what's alkyd urethane?

[tom chamby]

I was restaining and factory finished door that was installed about 6 years ago. I sanded the areas that were sun damaged and had a perfect match with a Minwax cherry stain. 2 1/2 days later I put on the minwax satin polyurethene and white blotches appeared. What's that about. My paint dealer said the stain hadn't dried. I've never heard of that. I did restain the whole door for blending purposes, but when I came to put the polyurethene on it looked as though someone already put a coat on...the shine and all. any suggestions?
Tom