Spalted Wood for Back and Sides?

[jv123]

I have some very nice fiddleback spalted maple I've had for many years - having got the bug to make a mandolin (almost finished with my first flat-top), I am considering a second, fully carved A-style, and am considering cutting this into a blank for bottom and sides.

Would you caution against using spalted wood for bottom/sides? It's not "punky", and some of it (on one side of the black line) is unspalted - but the spalted part is definitely less dense. I'm considering using a blank with majority unspalted for the back (but there will be some spalted at the edges), with unspalted for the sides (for structural integrity).

Any advice?

Also - another question as I finish the first mando. I'm reading "The Mandolin Project" (awesome book). The neck join is at the 12th fret for the flat-top - but for various reasons I'd like to have the join about a couple mm shy of the 12th fret. Will that have a bad effect? I figure I can tweak the bridge so it tunes properly. Of course, I am shaping the fret board so that where it hits the neck join it will be the same as that dimension for the body.

Thanks for any help out there on either/both questions.

JV

[Mario Proulx]

The spalted maple will be fine for the back, as long as you thickness it accordingly, but I'd worry about bending the ribs. I've used spalted maple and spalted birch for bindings on guitars, and it's a bear to bend! It wants to break without any hint of a warning. If you do proceed, I suggest you bend the ribs first, and if you get those done, only then go to work on the back's carving. It would be a shame to have a nicely carved back only to find that you used up all your other spalted maple and didn't get any ribs out of it.

If it does prove impossible to bend, you could thin it to veneer thickness, and make some laminated ribs, using solid maple backing.

It'll be pretty, though! go for it, and show us the results when you're done!

Oh, and wear a good mask when working it...

[martinedwards]

the spalt is mould (of course you know that) which must be killed before you use it. it MUST be kiln dried, otherwise it'll keep eating the wood and all your hard work will disintegrate.

I have heard of folks flooding spalted wood with CA to strengthen it after shaping.

[jv123]

Thanks for this, both of you. Confirms in some ways my own impulses. Not all of the board is spalted - as you likely know, rot works in a sort of "wave", and one side of the black line is perfect maple, the other side is less dense, but (having been kiln dried) is stable - been in my shop for over 10 yrs.... I will make the sides from the non-spalted part of the board.

I also have some European steamed pearwood - enough for back/sides and several necks. Thinking that maybe mandolin #3 will be pear....

Thanks again!

Jeff Vamos

[Graham McDonald]

Hi Jeff

The neck/body join is usually on a fret position because it looks neater A little either way isn't going to make any difference.

cheers

graham

[John Arnold]

it MUST be kiln dried, otherwise it'll keep eating the wood and all your hard work will disintegrate.

I don't think that is true.
I believe that the fungus will die on its own, once the MC is below about 12%. I have many pieces of air-dried spalted wood that have not 'disintegrated', and some of them are over 20 years old.
Spalted hackberry. I spalted this in my back yard. The large limb (18" in diameter) came down in a storm. I cut it into pieces 2 feet to 4 feet long, and let it lay for 8 months to 16 months.

[martinedwards]

I believe that the fungus will die on its own, once the MC is below about 12%.

you could be right, but I was under the impression that mould is a tricky little enemy and will go into a dormant state......

until the RH rises again.

it THIS case the wood has been kiln deied anyway so no problem, personally?

I'd prefer to keep my back covered!

[Gary McMoran]

For what it's worth, I have a Rigel A, with the industrial finish. If you look close you can see some spalting on both sides of the back. You can also see it looking through the sound holes. Not a lot of spalting, but some. Maybe that's why they used the industrial finish on these? Can't tell about the sides, but Rigel sides are different thing all together anyway. I've had it for several years and no problems.

[John Arnold]

I was under the impression that mould is a tricky little enemy and will go into a dormant state......
until the RH rises again.

Theoretically true, I suppose. But if your wood is that wet, it is totally useless for instruments. The wood I described has been stored in covered outdoor conditions, where the MC ranges above 10% during wet periods here in the SE US. I know for a fact that the fungi cannot grow under those circumstances. And that is much wetter than the instrument should be kept.

[Joe Mendel]

Sorry to get off topic. Gary, I'm not sure what you mean by industrial. If you mean thick I believe you are mistaken, I was told by Pete Langdell that the Rigel finishes were actually very thin nitrocellulose.