Do I poly the underside or not

[lcm1947]

I am working on a coffee table and was wondering if it would be necessary to put poly on the underside of the top and the shelve that it will have or would it hurt anything if I saved this step? The main reason I'm thinking not to is since it is so low to the ground I doubt if anybody would even notice it ever. Anyway, what do you guys think?

[newood2]

A sealer coat wouldn't hurt.

Howie

[RodKirby]

ALWAYS wise to seal!

[LCHIEN]

I don't think it needs ten coats like the topside but they say a coat or two evens the rate at which the moisture enter or leaves the wood, keeping it in balance and preventing sever warping when there's a weather change.

[drumpriest]

Yep, I'm with these guys, you should treat it with 1-3 coats to ensure that the top doesn't warp on you over time.

[bdk5]

I don't remember where or when, but one of the mags (either Wood or Popular Woodworking in the last year or so) addressed exactly this issue to test the theory of whether a surface will warp if only one side is sealed. I don't remember the specifics, but the outcome was that leaving the bottom unsealed did not contribute to warping. I take no position--just reporting what I read.

[bthere]

I think a sealer coat or three should be added. Over a long time there could be warpage that wouldn't necessarily be seen in a short term test. It is also good for keeping any splashes or drips that get underneath from causing damage. If you live in a house with kids or pets, you know that you can get spills in impossible places.

[scmhogg]

By all means seal the bottom. Last year I bought a sheet of 4x8 3/4" birch ply at HD. I primed one side and decided to wait until the next day to do the other. By then the sheet had a 4" cup. It corrected to nearly flat when I did the other side. Whew!!

Steve

[lcm1947]

Thanks guys. While the test may be correct and I do appreciate you mentioning it I think I'll go with sealing it -just in case. Thinks again to all.

[Ed62]

Even if there were no advantage to doing the bottom, it will look more like a professional job if you do. Now that you know that, you won't be able to sleep unless you do it.

Ed

[SARGE..g-47]

Morning Mac...

I am not familar with the test results that were posted above, but my question to who ran the test would be:

If you go to the trouble of letting the stock acclimate to a proper 8%-12% moisture content, "Would you use half a raincoat to keep what your putting inside the raincoat as close to the same condition of what you put in the raincoat before the rain"?

End grain is a must as that's where the largest draw is. But.. if what I stated above makes sense to you personally... I would treat it the same on all exposed surfaces. You can get away with 3 heavy coats directly brushed on the bottom, as it won't be seen.

If someone "picky-picky" crawls up underneath to notice and complains of the non-show quality, shoot them and call 911 to report an intrusion by a perpetrator who you "had" to shoot in self defense.

Regards...