Polyurethane suddenly turns gummy on kitchen table?

[Michael Dayton]

Hi gang,

I have a kitchen table which was refinished about 5 years ago. It had 3 coats of poly on top, which had cured nice and hard and have provided good protection over the years.

A few weeks back, I noticed that the edges of the table near some of the chairs are getting gummy, although the edges where people don't sit and the middle are still rock hard. I can scrape up sticky finish using my fingernail now. (It is about the consistency of really hard candle wax in those areas).

Of course, I have to refinish. But, I wonder what happened. I have read about "gummy poly" before, but it seems to be a problem right out of the can, having to do with application, humidity, or quality control at the factory. I've never heard of ploy spontaneously "un-polymerizing" after several years of being cured.

Since it happens only where people sit, could this have to do with skin oils or acids? (My arms rest nicely right where the worst areas are). Spilled foods? I thought poly could resist nearly anything except special strippers.

Anyone have advice for a better top coat than poly for the refinish? I loved it for 4.9 trouble-free years, and am leaning towards using it again.

Thanks!
Mike

[Michael Dayton]

I should mention my wife is a bit of a clean-freak, and this table never has spilled food sitting on it for any length of time. It is wiped down with a clean damp (water only usually) cloth after every meal. (i.e. I didn't leave a puddle of Vodka on it for a weekend recently). :D

[Steve Schoene]

Polyurethane varnish of the single-part DIY variety is basically just another varnish that is a somewhat more abrasion resistant because of the polyurethane resin added to the alkyd resin in the varnish. Without having any real scientific basis for it I'd expect a non-poly varnish such as Behlen Rockhard to hold up better in the circumstance.

How about plastic place mats or table cloths? The plasticizers in such things can affect finishes.

Also try a thorough cleaning. You may find oil and dirt for skin may have accumulated and are on the surface mascarading as failing varnish, though from your description that doesn't really sound like it is what is happening.

[Howard Acheson]

As chemical resistant as oil based varnish is, years of frequent cleaning with aggressive chemicals will eventually deteriorate the finish. Years of contact with the oils on human skin will also cause the finish to become gummy.

As Steve suggests, try using some mineral spirits to wipe the area. If the finish is still good and you're only dealing with years of gunk, the mineral spirits will not hurt the finish and should clean up the gunk. If it cleans up, check to see if there is still a finish. If not, it's time to chemically strip and refinish.

For a new finish, I would suggest either Waterlox Original Gloss or Satin of Behlen's Rockhard. Both are excellent finishes for hard used surfaces. I would also go to at least five coats. Three is a little skimpy for hard used surfaces like an everyday kitchen table.

[Michael Dayton]

Hi guys,

It is definitely the finish and not gunk. Thanks for the advice on brands; I'll look for those. I'm pretty sure I bought whatever can at the big box I saw which had the word "poly" on the label last time. This time I'm a bit more aware and can be choosier.

Thanks!
Mike