Seeking some advice - best finish for fine-detail woodcarving

Hi Everyone,

I’m new here, and a bit of a newbie to woodworking. I am hoping someone can help me select an appropriate method for finishing a project that I’ve nearly completed.

As as spare time hobby, I’ve been creating a 3D sculpture made from white oak. The sculpture is made from many (30) oak tiles about 2×4” glued together to make a hollow structure. Each tile has a lot of very fine detail carved into it using a CNC machine (to a depth of about 1/4”). I’m nearing the point where I can glue the final pieces on to close the structure up, and once that is done I won’t be able to access the interior of the sculpture any more.

I need to select a finishing method to achieve the following (in approximate priority order):

1) Protect the surface from dust and fingerprints/stains. The sculpture will likely be picked up and handled (although I hope to limit the handling).
2) If possible offer some protection against warping/cracking. Several of the tiles have bowed by up to 1/16” and one shows signs of a crack on the underside (possibly a result of a sudden change in room humidity).
3) I would like a matt finish. Since the surface relief on the tiles is best viewed when lit at a low angle, lots of tints and reflections from a glossy finish will detract from the carving.
4) I would prefer a finish that is reasonably close in color and look to natural timber (although I don’t mind some mild enhancement of the grain, and will tolerate some mild color change/darkening).

Other issues that I need to consider:

5) The surface is not smooth as you would get from sanding: even flat areas of the tiles have fine ridging from the passage of a small milling bit (ridge width would be around 1/50-1/100”). I actually want to preserve this texture.
6) Because of the above, and the larger carved details, I will not be able to sand the surface either before or between coats of whatever is used on the surface.
7) Because of the fine detail and high relief of the carving, any finish that tends to ‘pond’ in (hence fill-in) fine hollows could be a problem.
8) Once I glue the last pieces into place, I won’t be able to access the interior of the structure any more. I therefore need to decide at this point whether it is important to apply a finish to the inside of the sphere before completing the gluing.

Given these restrictions, I’m figuring I probably have to go with an oil finish (boiled linseed oil) which – while it won’t offer a great degree of protection – might be enough to prevent fingerprint stains. I’m a bit nervous about the tendency of linseed oil to stain the wood. I am wondering if there is a thin colourless water-based polyurethane that might apply that produces a matt or low-gloss finish?

I would be very grateful for any help or suggestions from someone with more experience than myself (which – face it – would probably be everybody here).

Thank you!

Suggest you spray on lacquer, or paint with Danish Oil, often used on timber counter tops in some hardware stores

I've been a wood carver for some time. First of all, you need to know whether you are working in red oak (Quercus rubra and similar) or white oak (Q. alba and similar). The red oak group of species is open-porous and a vessel element paste sealer is needed for that. . . . but it's a little bit late!

One coat of Minwax Tung Oil Protective Finish will give you both protection and a matt finish (3 coats is water-wet glossy). Satin or matt poly would do, as well.

Instead of sanding, wait until you can't smell the TOPF and gently rub the surface with the very coarsest steel wool that you can find.
The fibers are flat, not prone to breaking, and act as a million little chisels to cut rather than shred like sandpapers.

Please show us the result!

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Originally Posted by Dengue

Suggest you spray on lacquer, or paint with Danish Oil, often used on timber counter tops in some hardware stores

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Thanks Dengy! I'll look into Danish Oil - I haven't heard about that one. Won't lacquer have a high-gloss finish?

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Originally Posted by Robson Valley

First of all, you need to know whether you are working in red oak (Quercus rubra and similar) or white oak (Q. alba and similar).

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Thank you for your reply! The wood is American white oak so hopefully I don't need a sealer. That was lucky - these are things that a first-timer never considers!

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Originally Posted by Robson Valley

One coat of Minwax Tung Oil Protective Finish will give you both protection and a matt finish (3 coats is water-wet glossy).

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Great - I'll look into that product. It's hard to picture what the finish is going to look like but I'll do some research before I go ahead. Do you think that it would be important to treat the inside of the structure (so that both top and bottom of the tiles gets the treatment)? The only reason I can think of for doing this is to ensure that both sides get the same treatment in the hope that future warping/splitting is prevented. I'm ready to glue the last pieces into place and need to decide now whether to go ahead or wait until I've applied finisher.

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Originally Posted by Robson Valley

Please show us the result!

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Yup. When it's finished I'll post some pictures. Thanks again!

White oak is waterproof = wine/whiskey/rum/sherry barrels are made of untreated wood. You really dodged a bullet that time.
TOPF is quite thin and runny. I'd brush on a coat, whether it appears to soak in or not, and leave it to set up/dry. No smell in a week.

You can't totally stop warping and splitting. However, you can slow it down by using a finish which is essentially waterproof
to prevent any sorts of sudden humidity changes = moisture content in the wood. Anything is better than nothing.

My wood carvings crack, especially the ones standing out in the weather. It's "mind over matter:" I don't care so it doesn't matter.
I've seen a pair of 30" Raven birds that I did maybe 5(?) years ago. Sun and shade, rain and shine, hot and cold, they cracked.
Just goes to show that good quality black exterior house paint is no better than anything else.

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Originally Posted by Robson Valley

You can't totally stop warping and splitting.

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Yep - I figured as much. Given this, is there any benefit from using an oil-based treatment on the *inside* of my sculpture as well as the outside? Each (~1 cm thick) tile that makes up the structure has an inside and and an outside face. Since the inside won't be seen, there is no need to protect it from handling, nor create an aesthetic look for it. The only reason to treat the inside is if application of an oil finish here will help prevent warping/cracking, or if application of an oil finish to one side of each tile only will exacerbate warping.

I need to decide whether to glue the last tiles into place. Once I do, there is no way to access the interior any more, so the decision about whether to treat both inside and outside has to be made now.

Thank you again for your advice!