08-14-2011 06:54 PM
I have a coffee table surfaced with oak veneer and I'm refinishing the top due to water marks, scratches, etc. I sanded the blemishes out and lightly sanded the entire surface with 220 grit to try to get a uniform surface. After applying three coats of wipe on poly the finish is very dull and streaky. I want to take the poly down to the bare wood to try to start over, but I'm concerned about going through the veneer. Should I sand it all down, or use some kind of stripper first? I don't believe the wood is stained, just finished natural.
08-14-2011 08:49 PM - edited 08-14-2011 08:50 PM
Most likely you will sand off the veneer while trying to remove the poly.
I don't use poly so can't tell you what to use to remove it.
Some sort of stripper may be in works.
Steve, and other guys, will let you know what might be best for your situation.
08-15-2011 03:56 AM
…to the WOOD Magzine Forums, particularly to the Finishing & Refinishing Forum. I hope you will visit often. You will find a number of accomplished woodworkers and finishers here who stand ready to assist you with your finishing and refinishing questions.
Sanding to remove finish is almost never a good idea. In this case I suspect that the streaks in your finish are a direct result of your sanding. Over time wood develops “patina” as a result of exposure to UV and oxygen. Patina changes the color of the wood. In some species the change is obvious (cherry, for example) while in others, oak being an example, the change is far more subtle. When finish is removed by sanding the patina is removed, though not uniformly. When a new finish is applied streaking becomes evident.
A second possibility that cannot be completely eliminated from consideration is the failure to properly stir varnish that contains flatting agents. If your varnish (poly) is any sheen other than gloss and you did not thoroughly stir the contents before (and during) application the flatting agents may very well have settled to the bottom resulting in reduced sheen in some areas and near gloss sheen in others.
If the streaking is the result of irregular sanding through the patina the only solution will be to strip the finish and apply a light stain or dye (preferable dye) to even the color before finishing. If the problem is insufficient stirring (mixing) of the varnish than simply stir and apply another coat of varnish.
If the finish must be removed to add color do not sand (you dodged the bullet once, don’t put yourself in the line of fire again). Use a chemical stripper containing methylene chloride and follow the instructions on the can…