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"Ambrosia maple" is, as I understand it, a form of spalting caused when insects burrow into the tree and introduce a fungus. It produces darker stains through the light-colored wood, roughly following the grain direction, ranging from a few isolated streaks to a chaos of overlapping "brush strokes". The holes are also present, of course, to add a bit more character.

It's often surprisingly inexpensive for a fancy wood, perhaps because the standard grading system considers it a flaw rather than a feature.

One of the local woodworking stores got a batch of this, and I picked out a few boards I liked for a project. (Blanket chest, so I'm leaning toward one or two splashes of pattern per side, possibly with a more chaotic/denser pattern on the lid.)

Question is, is there a recommended finishing technique that will best display the color and detail of the spalted patterns? Or should I just finish it as I would any maple project, going light on added color to let the contrast be seen? There's also the question of whether to fill the holes with colored epoxy or leave them.

Some of this, of course, will be a matter of taste. But if there are any known tricks or pitfalls...

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Question is, is there a recommended finishing technique that will best display the color and detail of the spalted patterns? Or should I just finish it as I would any maple project, going light on added color to let the contrast be seen?

In terms of clear finishes I think the standard, or I should say your standard, for finishing maple will work for this too, broadly speaking. Some people aren't a fan of any finishes that add more yellowness to maple, preferring to keep it as light as possible by using a 'water-white' finish (most waterbased finishes, or lacquer), while others don't mind the yellow/orange tone imparted by shellac or varnish. Pick your poison.

The one caveat I'd add is in relation to highlighting any figure. Because this beetle attack and staining can occur on any random acer, ambrosia maple planks can also exhibit the whole range of features seen on unmarked maple (both soft and hard). Where this coincides with rippling or 'curly' figure in particular I think the finishing regimen should seek to highlight the rippling as you would otherwise, as IMO it's a crying shame to see this finished in such a way that it looks a bit flat, like on the left here:

Rippled figure unenhanced v. enhanced

One additional concern would be if you have areas that are punky, I don't believe it's anything like as common as on conventionally spalted woods but sometime the fungal attack has gone a bit too far and made the wood soft and spongy, and it's a PITA to try to work it and finish it. Often consolidating the area with a penetrating wood hardener, or superglue, is the only way to get a good surface and even at that there can be some slight textural difference between it and the unaffected wood which are only hidden if you build a full film finish.

There's also the question of whether to fill the holes with colored epoxy or leave them.

I'm of two minds about this, while I'm a fan of filling holes/voids usually (I like the look and that you don't leave a hole which can trap dust and other crud, making them very ugly) the holes here are a specific feature of this wood so it might actually be desirable to leave them, to showcase them.

  • If I do fill the holes, I'm leaning toward something like a black epoxy, keeping them visible while levelling the surface for finishing. – keshlam Aug 3 '16 at 13:11
  • (Fwiw, I am leaning towards pushing it somewhat into the yellow range to harmonize w/ existing furniture in that room. That may be as simple as using a shellac base layer, or boiled linseed oil, or an oil-based varnish. As is often the case, I suspect I'll need to experiment on some scraps.) – keshlam Aug 3 '16 at 13:15
  • @keshlam, yep all of those options will work to add some yellow, just to note though that if you want the colour to stay consistent shellac is the one to go with. Both BLO and most varnishes get noticeably more amber over the years (as does tung oil if you were tempted to use that instead, further reducing any perceived advantage from it!) – Graphus Aug 4 '16 at 7:23
  • That point about how finishes age probably deserves to be its own Q&A, so folks can find it in the future. – keshlam Aug 4 '16 at 9:43
  • @keshlam, agreed. It has been touched on in passing in a number of Answers but no Q&A specifically on that as far as I know. – Graphus Aug 4 '16 at 18:06

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