What to do with the underside of a table top

[brizylad]

G'day All,

I'm just finishing off the finishing of a silky oak computer desk, and it dawned on me.....what do I do with the underside of the top.

Obviously, I don't need to go to the same extent as the top surface, but what do you do?

The top surface has been sanded to 600, sealed, and 4 coats of Wongo's brew. Underside has only been rough sanded to 120 and no finish applied.

I'll attach a couple of pics some time over the weekend.

Also..what to do with the bottom of the legs?

Stuart J.

[Tung tied]

Hi Stuart,

You need to apply some sort of finish to the under side and the bottom of the legs. This will help prevent cupping / warping due to uneven moisture absorption. Usually a couple of coats of what went on the top is best.

Cheers

Bryan

[RufflyRustic]

Definitely sand it so there are no rough bits to catch on clothing or fingers or legs and Definitely apply a couple coats of finish as well.

This is essential so that the timber surfaces are more 'balanced' and helps to reduce any cupping of the surface.

Sorry, I haven't got the wording of that reason quite right, but yes, you do need to finish the underside of a desk or table. It helps to stop any cupping.

cheers
Wendy

[jmk89]

I used to think this was needed before I read an article by Megan Fitzpatrick (in Pop WWing in the last 18 months) which suggests that it doesn't help at all. I have not done it since and have not seen any cupping

[RufflyRustic]

How interesting is that! Would it depend on the design of the desk and how the top was made/attached perhaps?

[Arron]

Could depend on timber or climate zone or perhaps stability of indoor environments, perhaps.

I'd love to hear Megans reasoning. Anyone able to find a copy ???

Arron

[pjt]

mmm I would have said do both sides, top and btm, the idea is that moisture movement into and out of is equal on both sides of the piece of wood, uneven moisture movement into or out of sure does cup/curve a flat piece of wood if it is free to move, if restrained it will still want to move which puts stress onto a joint or screw or attachment.....be interesting to find out the guts of the article.

Pete

[TP1]

It may not matter for plywood or MDF, but solid timber will experience greater variations in moisture content when it is not sealed. The effects of moisture absorption/loss are inevitable over time, however small they may be. You can be lucky for a while but for the sake of slapping on a couple of coats of finish to the underside, why take the risk?

[jmk89]

My answer to the 'why take the risk'? response is "why do the extra work if it's not needed?"

Just look inside antiques - no finish. So why should we bother?

[jmk89]

Megan Fitzpatrick's article was in Woodworking Magazine, Summer 2009. There is also an article (http://woodworkingnow.popularwoodworking.com/BrowseArticles/Finishing-Essentials) which you can purchase for USD1.99 from Popular WWing by Bob Flexner which similarly says it is unnecessary to finish the other side

[TP1]

Just look inside antiques - no finish. So why should we bother?

Maybe more would have survived if they did bother.

[Wongo]

I think it is important to seal the table top both the top side and the bottom side. I always finish the bottom side but only with 1 to 2 coats.