I have a piece of furniture to which finish I have to fix.
It had opaque lacquer paint.
It has horrible brush marks all over the place.
Using a left over sample with the same finish as this furniture, I tried a layer of polyurethane (Minwax Oil Base Stain) on it. Beforehand, I sanded very lightly with 220 sandpaper, dry, cleaned the dust with a rag with some mineral spirits. I applied one hand.
Well, the resulting finish of polyurethane looked great, but it has some bubbles and dust.
So, to get rid of these details, I tried to fix this by sanding slightly with 600 grit sand paper, using mineral oil for lubrication. I have done this before at other works, and worked fine. But this time, the result was a finish that resembles the horrible lacquer finish it had, with grooves all over the place.
I have no idea what happened. It looks like the polyurethane adhered to the lacquer without really filling the brush marks, but adhering a thing layer on the pikes and valleys left by the lacquer. So, what it's left after the sanding is again, the previous grooves set up with the lacquer finish.
What would be a proper way to do this? Am I skipping a step?
Oh, btw, I also tried sanding the brush marks with #220 grit, but at some parts I sanded so much that the lacquer was removed, leaving the bare wood exposed. And anyway, the sample with the sanded lacquer, looked the same at the end of the same process of applying polyurethane then sanding with #600 and mineral oil.
What else can I do?