Finishing Both Sides

[sCORCH]

Hi All,

I recall this topic coming up a little while ago, but can't seem to find the thread at the moment, and I'm not sure how pertinent it was to my situation.

I have a largish blanket box that I am finishing up for SWMBO's parents for Christmas. Top is roughly 900 x 650 of 17mm thick pine. I have stained both sides of each panel.

I will be clear coating it with a Wattyl water based estapol, and wondered whether it was necessary to do both sides. The only argument I can think of to support the extra effort is to avoid any possible warping. However I am not sure how much extra water content the estapol will add to the timber, and the risks of whether that is likely or not. The piece will have TV possibly sitting on it at some stage, which is likely to add some heat to the top panel.

Does anyone have any suggestions as to whether I can get away with just the outside being coated?

Thanks,
sCORCH

[Pusser]

Much period furniture is not finished on the inside and survives quite well. Shellac or french polished pieces often have just a seal coat.

However, I think (and I am no expert) that the better the finish in terms of moisture resistance the more important it is to seal both sides. If the finish allows some absorbtion of moisture then the differential across the board may not be enough to warp the board when it is properly secured. If the seal is impervious to water as is estapol, the more likely a significant differential will occur as the estapol side will not absorb any moisture whereas the unfinished side will. This assumes well dried timber of course as the estapol will seal in residual moisture and the wood will dry more quickly from the unfinished side. It all depends of course on the humidity range where you live.

Personaly if using estapol I would at least seal the inside.

[echnidna]

After having problems years ago I adopted the practise of always sealing both sides unless I am using an aromatic timber such as camphor oe western red cedar.

[Bob38S]

Go with the sealer at least.

[sCORCH]

Thank you all for your suggestions - looks like I can't take the lazy way out this time!

[MacS]

Furniture and kitchen cabinet manufacturers do not seal inside of their pieces.

Its probably a personal preference thing.

[journeyman Mick]

Furniture and kitchen cabinet manufacturers do not seal inside of their pieces...........

Unless they live in a wet tropics area, in which case furniture will grow mould on any unfinished areas, inside or out.

Mick

[MacS]

In those cases, it will also grow a mold or fungi right on the finish too..

[astrid]

I always put a seal coat of shellac on even period pieces.
not to prevent warping as its of course completly dry timber, but to freshen it up and making cleaning and dusting easier.
Its only a rough coat and only takes a few miniutes.
Astrid:)l

[MacS]

If your a woodworker, and your make up one piece of furniture at a time, and you have the time to seal inside the pieces it certainly won't hurt.

Sealing inside the drawers is a common finishing practice. Usually, only the more expensive factories seal inside their furniture.

Even if you were to seal inside the pieces with Shellac, it will not prevent the tranfer of the moisture content (MC) from going through the coatings and the woods.

[journeyman Mick]

In those cases, it will also grow a mold or fungi right on the finish too..

True, but it will wipe off the finish much easier than off bare timber, which BTW will get unsightly and permanent stains. Besides, the mould and fungi won't grow as readily on a finished surface.

Mick

[MacS]

That depends on what chemicals you use to remove the mold or fungi, some chemicals will also remove the shellac and then effect the wood. Chances are the fungi and mold with go down into the wood, so both will need to be removed.

"Besides, the mould and fungi won't grow as readily on a finished surface."

Your comment about a "finished surface" has never been proven. it is still hearsay.

Its a personal preference thing, the "sealing" will not help, in most cases its about the equalibrium of the moisture content in the home.

Shellac is too pourous, and is not a moisture barrier, so it will do nothing to prevent warping.

[journeyman Mick]

................Your comment about a "finished surface" has never been proven. it is still hearsay..................


I've been living, working and building furniture in the wet tropics for over a quarter of a century now and I can tell you from personal experience that sealing (with nitrocellulose lacquer) will help retard or discourage mould and fungi and that a wet cloth will remove them from a lacquered surface. Furthermore, they will not get through the lacquer to stain the timber and that unless you're using lacquer thinners to remove the mould you won't affect the finish. So yes, I guess that's only hearsay, not proven by rigorous scientifc test (that I know of anyway). If you've ever lived in a wet tropical area you would know that unsealed timber can develop a thick carpet of mould, whereas a sealed section will grow much less mould.

Oh and I can also tell you that if you seal one side of a table and not the other it will cup horrendously. Never been silly enough to do this myself, but fixed up other people's mistakes. Can't comment about the suitability of shellac as I've never used it, only ever used NC lacquer, acid cure lacquer and polyurethane, both single pot and two pack.


Mick

[Cruzi]

You could try just using a timber sealer inside and giving it a light sand, this will not affect the appearance of the inside to much.

We don't live in tropics but do have high humidity, without the mould problem of the tropics, sealing both sides of anything is essential or timber cups very quickly.