How do you avoid tiny Black Mineral Streak/Knot SURPRISES in Hard Maple?

[Nick Sorenson]

I almost titled the thread "Why Knot?!?-Hidden Maple knots driving me nuts!" But that was a little bit cheesy and not descriptive enough. But I am pretty frustrated with the lack of predictability with Hard Maple. I'll have a piece that looks great. Cut it to shape and run a profile or two and find hidden under what looked to be a pretty piece of wood a tiny black line usually about 1/4" in length and about the diameter of a pencil lead buried in there. Other times I find something that looks more like an actual knot (brown in color) that runs long ways buried in a board. You can't see it at all from the outside but when you cut into the board, there it is but again, no clue that it was hiding under there (that I could see anyways). Are there any cues/clues to look for when working with Hard Maple to know this is coming or at least assume that they might be there somewhere (i.e. likelihood in a particular board or batch)? Pretty frustrating because sometimes I don't find the surprise until I'm just about done with a piece and cut or sand the last little bit of material off. Any clues to watch for?

[Jamie Buxton]

The other thing those little black inclusions do is nick my planer blades. I've switched to birch or beech when I need a light-colored hardwood.

[Peter Quinn]

Well, a least its not cherry! Cherry is more expensive and even worse in that regard.

[George Gyulatyan]

Use plywood.

Seriously. While understand that sometimes those are undesirable, but you're dealing with a natural product where no pieces are alike, so it is what it is.

[Nick Sorenson]

I just wish I could figure out a way to know when to expect it. I build instruments so for one of these marks to show up after gluing an expensive fingerboard to it and spending a few hours in machining and sanding, it's an expensive piece of firewood or a second. It's pretty frustrating. I don't feel I can ship with one of these 'imperfections' if that's what it can be called in the visible area. So that's where being able to predict or at least have an idea that one is possible would be nice.

[George Gyulatyan]

Yikes. I guess in that case using plywood would be out of the question then! :)

I understand your dillema.

I found a thread in talkbass forum about this same subject. There is a quote from "TEXTBOOK OF WOOD TECHNOLOGY" where it pretty much states that unfortunately there doesn't seem to be a good explanation of how mineral stains occur in the first place, let alone how to predict them.

[scott vroom]

One of my hardwood suppliers (Macbeath San Jose) pays a premium for units of 4/4 that are nearly free of surface mineral stains. When milling wood from these units I rarely uncover mineral staining.