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I'm building a chess board -- I decided to use jatoba and maple for the board itself, (and am using wenge and maple for the trim).

After milling the jatoba, the exposed surfaces of the jatoba are no longer oxidized, which is a bit of a pity, as I specifically like the oxidized coloring. I'm wondering a few things at this point about the best way to finish these.

I'm assuming if I use a polyurethane finish, it will seal the wood, and prevent oxidization in the future. If this is the case, should I wait a month before sealing it? Will the wood still oxidize if I put an oil finish on it?

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    Hi, you are asking for opinions. Avoid subjective questions.
    – Volfram K
    Commented Jan 5, 2022 at 6:29
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    I have never used jatoba for anything, so I don't know it's properties, but all wood darkens in sunlight, with or without a finish.
    – bowlturner
    Commented Jan 5, 2022 at 13:18
  • Hi, welcome to Woodworking. I've edited your Question to make it come across as less subjective and also to make it more focussed — as originally worded there were in effect five queries, and every Question should ideally ask just one thing. Feel free to ask separate Qs about the parts I stripped out in my edit.
    – Graphus
    Commented Jan 5, 2022 at 14:40

2 Answers 2

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the exposed surfaces of the jatoba are no longer oxidized
I specifically like the oxidized coloring.
prevent oxidization in the future.

Wood actually darkens primarily due to exposure to light, not air1. Although oxygen may be involved it's misleading to call the colour change oxidation, and it would be more accurate to refer to the colour of older wood as aged or patinated 2.

Because the effect is mostly about light the gist of your last query is easy to answer:

Will the wood still oxidize if I put an oil finish on it?

Yes, wood will still darken over time underneath an oil finish, as it does under all finishes (ignoring finishes containing UV absorbers).

It's also worth noting that oil finishes directly darken the wood most of all finish options, so you'll see a marked change in the jatoba right from the get go. But note that oil finishes also bring out the yellowness of maple, so if you were hoping to keep it as pale as possible there's a trade-off.

If this is the case, should I wait a month before sealing it?

I've never worked with jatoba, but unless the sunlight where you are is very strong at this time of year, or the jatoba reacts unusually quickly (as cherry is reputed to) a month wouldn't be enough time to see a very noticeable change in the colouring3. But as noted the oil finish will take you a good way towards the colouring you were seeing prior to milling.


1 You can see this effect most starkly in the workshop on boards stored vertically where one face is towards a window. The window-facing side darkens and the opposite face (exposed to the exactly the same amount of air but much less light) doesn't change colour much or at all.

2 Hence the "patina of age" that is sometimes used to describe the tone of wood in vintage and antique furniture (something that restoration work may take pains not to disturb).

3 You might be able to hasten the natural darkening by directly exposing the board to strong light, e.g. by placing it right by a south-facing window, but note that this will also have its effect on the maple.

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    As always, it's worth noting that some testing should be done with the intended finish and some scraps of both woods. It may be that a single coat of finish brings the jatoba right back to the color desired. OTOH, it may take 6 coats...
    – FreeMan
    Commented Jan 5, 2022 at 15:33
  • @FreeMan, yes, good point. It's always important to test a finishing plan out on the wood you're using. FWIW though, I have rarely seen any colour improvement after about the second coat, the 'wetting' effect of finishes generally levels off after coat two (unless the finish is very dilute). But you do most definitely see improvement in optical effects with film finishes as you continue.
    – Graphus
    Commented Jan 5, 2022 at 16:21
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Polyurethane offers the best defense against the elements, but it comes at a price. Polyurethane is literaly clear cover of plastic over the wood. Some people say this gives it a cheap plastic feel and look.

Oil naturally effects the color of the wood. Some woods it darkens but some bright woods it brings out the light tones. Whatever effect it may have on the tones it does so in a very pleasant and natural way.

When it comes to oils there are also other considerations. Linseed oil is cheap and gives minimal protection but is a all natural finish.

You also have Danish oil which is a couple of notches up the fiscal scale from Linseed oil but it is a mix of oil and poly. This means it gives a far better protection than other oils although probably not as much as a straight poly finish.

Lastly, there is shelac. This is again anothet notch more expensive. The finish traditionally used for French polish.

This is the hardest finish. You are going to have to decide for yourself if it is worth the effort.

You should do at least three runs. You add the first layer of the shelac varnish. Then you add a tiny amount of mineral oil. This oil you have to remove with after a couple of minutes with methylated spirits. You then let dry. Rinse and repeat 3 - 5 times. The effects are spectacular.

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    This is somewhat misleading with respect to price; BLO, Danish oil, shellac, and polyurethane are all within a few bucks of each other per quart at both Home Depot and Woodcraft, and BLO isn't always cheapest. Also, the description of French polish is rather incomplete.
    – Caleb
    Commented Feb 1, 2022 at 20:39

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