Can you apply varnish over urethane finished wood?

Question

I put a coat of urethane on a previously coated wooden bar. I had no knowledge of the type of material that had been used on it before, but prepped the surface well and applied the urethane. Now it's peeling in places and has small bubbles popping up here and there. I've used varnish before and after using the urethane I'd rather go back to varnish. So if I was to re-finish this again, without totally stripping it down....what should I use?

Answer 1

No offense but eurethane is a POLY substance, while Varnish is not.

The issue of peeling may have caused by inappropriate prep in the first place, and an application too thin? The bubbles also are a natural phenomenon, occuring when POLY is shaken, or stirred too aggressively, or applied incorrectly,,,IE: Roller, or too much brushing. Temperature and humidity effect both.

Poly can be gently steel wooled after curing to remove bubbles and reapplied more gently. It will last probably as long as any human lifetime.

Varnish is acceptable of course, and the process isn't vastly different, but please use adequate ventilation and don't spend a long period of time inhailing either.

My first suggestion is to pull a piece of scrap wood from anywhere and do a test. Neither substance might go in one coat?

Apply the poly first, in any way you wish, since it's only a test. Create the surface finish you might stick with, and then apply varnish. I'd likely scuff the bad poly with sand paper, though the varnish will also show any defects, unless you use a varnich stain.

Rev. Steven

Answer 2

You will not get the finish of a commercially produced piece of furniture. By hand, for the best gloss finish use an oil-based clear varnish and build up coats. Allow each coat to dry and after half a dozen or more coats, leave the piece to harden for a week or two. Then carry on. In between each coat lighty denib and key the surface with some P240 or finer grade abrasive paper and use a sanding block. Wipe the surface over with a clean lint-free cloth in white spirit. In clear gloss varnish there is no reason why you cannot apply so many coats that it looks like someone has put a sheet of glass over the item. Doesn't work the same with a satin finish or varnishes with colour in them. Don't use a water-based varnish as it will not level out like oil (solvent) based product. As you are not a decorator your brushwork may let you down and stop you from getting the ideally flat finish.

Answer 3

Polyurethane and varnish do not mix - period. That's why it started to peel and develop bubbles. Since you have introduced the urethane to the wooden bar, putting varnish on top of that will only exacerbate the problem. To get professional results, you really should remove the old and new finishes completely. To do this, let the wooden bar dry completed, then thoroughly sand off the finish, and then you can apply a fresh coat of varnish. Be sure not to shake the can of finish because it will create air bubbles that can be transferred to the wood. Between coats, you could lightly sand with a fine sandpaper or steel wool. I prefer the steel wool because it does a great job of leveling off any pits and peaks, without greying the finish like sand paper. Once you're satisfied with the number of coats to produce a nice finish, you can further protect it by using a quality floor wax.
Apply it with a damp cloth, let it dry to a haze and buff it out to nice, deep and rich finish.

Answer 4

you will need to strip off all the urethane and any finish
left over from before. get all the way down to the wood.

Answer 5

yes i have don that i got the varnish from bed bath & beyond and its sooooooooooo perfect and my house is just so amazin and i hope ur house will be 22222222

Answer 6

sand it all the way down to bare wood. if you don't youwill always have trouble with it and it will look like crap.

Answer 7

you will need to strip it to get anything to work right!