Finishing wood with high moisture content

[Tim Barlot]

Hey folks, I'm brand new here...been searching the site frequently, but finally registered!

I was curious what the ramifications of finishing a piece (I will explain how) that has not fully dried?
I work with primarily natural edged slabs (walnut, redwood, maple) and with an oil finish of some sort (usually tung oil). I fully embrace checks and voids and deal with them as they arise. But I have a slab of walnut crotch which is around 2" thick and was cut about a year ago; it is currently coated with anchorseal. I realise that I should allow about a year per inch to dry, but what can I expect if I finish it now?
I plan on finishing all sides of the slab so there isn't uneven moisture loss.

Thanks

[Sam Yerardi]

Tim,

Others may have tried different finishing schedules and have them work for them. Hopefully those on this site that have can relate their experiences. Myself, before I would commit to any finishing regime on green wood I would research the finish I was planning on using. If you look at the timber framing industry, finishing wood is a somewhat different ballgame than finishing air or kiln-dried wood. There are finishes that are used and tend to be varnish-type or penetrating oil-type finishes. Bowl turners typically work with green wood but before they are done and ready for finishing, they do go through some period of trying to dry the bowl prior to finishing. Look into what chair makers (Windsor) do as they do a lot of work in green wood.

What is at issue are two things - the interaction of the finish with moisture being present, and the natural process of moisture exchange in the wood with its surrounding environment. The wood will try to get to a point of equilibrium as far as moisture content vs. its surrounding environment. By applying a finish that seals the wood, the normal progress is impeded somewhat. I'm not saying that this is a bad thing, it's just that now that the movement of water in the wood is impeded, it may affect how the wood now reacts as it is drying or getting to equilibrium. Where it finds equilibrium will depend to some degree on the environmental conditions around the wood, etc. Some finishes will break down in the presence of water or mositure, so having moisture present when the finish is trying to cure may be a problem depending on what finish you are using. I would lean towards an oil-based varnish finish, but again, depending on the moisture content at the time you are trying to finish it it could be a problem. I don't have first-hand proof of this but I would think that if you could theoretically seal the remaining moisture that is in the wood you might create conditions for rot or mold in the wood itself. It needs to be able to exchange its water content with its environment. It makes sense that an oil-based finish is typically used because there is nothing you can do to mix oil and water. Oil can only suspend in water.

[Howard Acheson]

What do you mean "is currently coated with anchorseal?" Is the anchorseal coating the whole slab or just the ends?

[Tim Barlot]

The source of the slab evenly coated the entire piece in anchorseal. I know this will slow the drying, should I get it off ASAP (with exception to the ends)?

[Howard Acheson]

>> I know this will slow the drying, should I get it off ASAP (with exception to the ends)?

AnchorSeal is a wax emulsion that totally prevents water and watervapor transmission. In other words, it will never dry because the watervapor in the wood can not pass through it. The board will be virtually as full of water as is was when the AnchorSeal was applied.

I can't advise you what to do with the slab. I have never worked with "wet" wood but some do. Hopefully they will chime in here and provide you with some advice.

Until then, and until you are sure the advice you are getting is valid, I would keep the slab encased.

[Sam Yerardi]

Howard has a good point. Given that it is a walnut slab of very good value, I would go to the trouble of seeking out someone with a kiln that knows how to kiln-dry thick pieces of wood such as slabs. A lot of kiln operators treat the wood differently during the drying process than say 4/4 or 5/4 stock because thicker wood during the drying process can move more dramatically, resulting in checks, splits, etc. I would leave it sealed until you can find someone first hand to look at it an recommend what to do. If you remove the sealer, the wood will start trying to reach equilibrium with the environment around it. The rate it does that at, the humidity v.s. the moisture content of the world, may significantly work against you. It needs to be done in a controlled fashion. And since it is a walnut slab as you describe I would take ever precaution I could to ensure that I've done all I can to stablize and dry the wood properly. Then finishing becomes a different situation.

[Jim Becker]

AnchorSeal is a wax emulsion that totally prevents water and watervapor transmission. In other words, it will never dry because the watervapor in the wood can not pass through it. The board will be virtually as full of water as is was when the AnchorSeal was applied.

I'm not sure this is "completely" true, but agree it's trouble for the entire slab to be slathered with the stuff. It typically is only put on the end grain to slow moisture loss at that point for more even drying. (It could be worse...someone could have melted paraffin and put it on at high temps. That would really keep the moisture inside!)

[Tim Barlot]

There is a very thin coat, which from my understanding will simply slow the equilibrium process. It was originally applied to keep the wood as stable as possible for whatever project the buyer has in mind (turning in mind).

I have had the piece for about a week and it has already developed two checks in my dry winter climate, so it is drying. Should I still take the ancholseal off the flat surfaces?

I considered getting it to a kiln (along with another large walnut slab I have), but I am less fond of the color of kiln dried walnut. Anyone have experience with color changes in kiln dried walnut? The color seems dull/less vibrant in my experience.

[Jim Becker]

As long as they don't steam it, any color changes will be less noticeable with kiln drying. It's the steaming that changes it all to the same dull brown...

That said, walnut is pretty stable and I personally still prefer air-dried stock.