Wood – get brush marks with oil-based polyurethane

hardwood-refinishingtable

I’m trying to refinish the above table but having problems with streaking polyurethane. Using Minwax Fast Drying. The process has been as follows; sand, stain and applied poly using a Purdy brush for oil and following the directions on can. The brush left terrible brush marks.

Waited the recommended time and lightly sanded until smooth with no visible marks and put another coat. Looked terrible. I’ve tried recommended foam brush, tried rub on method by diluting poly with mineral spirits and the last attempt was with 100% Lambswool applicator. As you can see in pic still looks bad.

Could it have something to do with the way I’m sanding. Used a dewalt sander starting with 80 grit sandpaper and ending with 220. Although on the last few coats I used 320 and 400 doing a hand sanding just don’t know where to go from here other than Starting the process over. We bought a sprayer today hoping that would help.

All suggestions welcomed
If you enlarge photo may can see better. This was taken in garage and only half of table is getting full natural lightenter image description here

Best Answer

My hunch is that you're applying too light a coat and/or working with it too long. I've used Minwax poly many times, and it's almost miraculous how it flows to a smooth finish. It should look very glossy after you brush it on, and you shouldn't work it longer than necessary. Your final lap should be within a minute or two of application.

I tend to apply fairly heavy, then work it out to the point where it doesn't run. Get off it as soon as that's done to give the surface skin time to flatten itself out. Any brush work done once the poly starts to set will remain.

Note that I never sand beyond 150 or 220 grit, depending on what I have on hand. Polyurethane spans that texture just fine.