I was reorganizing a shed yesterday, and came across a large piece of spalted bigleaf maple I bought three or so years ago from a guy in Washington State (I live in Arizona). One side, and two endgrain ends, of the block (it's big, 22x22x7) had a strange appearance. When I looked at them more closely, the areas of black spalting (in this piece, as well as a couple others, there are contiguous patches of black, rather than the nice spidery lines we all love) had "bubbled" -- there were blisters sticking up off the surface 1/8" to 1/4" high, anywhere from 1/4" to 1" across. They're hard, and when I cut through them with a knife (it appeared to be a thin shell of wood forming the bubble), what appeared inside was white, and although it was hard, it crumbled easily.
What is this? Is there any concern about this being a nasty form of spalting I should avoid, or is it safe to turn?
My take on turning spalted wood is to do it only when wearing a respirator. You can sometimes get allergic reactions with 'plain' woods - such as the rosewood family - but the spalting in spalted wood is caused by Fungi and not something you want to risk getting into your respiratory tract.
I haven't turned any spalted maple yet, but I have sawed and stored a lot of maple and other woods over the years. My take on spalted anything is that spalting is rotting. If you don't do something with the wood to stop the process, its gonna rot away sooner or later. I have brought home spalted logs, maple and other woods, and had them sawn right away. I only air dry my wood. Sometimes that spalting seems to be stopped by stickering the freshly sawn wood, but sometimes it keeps right on going. Then its firewood as far as I can see.
In my admittedly meager experience, the spalting stops when the wood dries. What the actual moisture level stopping point is I don't know. But I've got spalted birch, poplar, and myrtle that I've had for years and the spalting has not continued on them.
:> My take on spalted anything is that spalting is rotting. If you :> don't do something with the wood to stop the process, its gonna rot away :> sooner or later.
: In my admittedly meager experience, the spalting stops when the wood : dries. What the actual moisture level stopping point is I don't know. : But I've got spalted birch, poplar, and myrtle that I've had for years : and the spalting has not continued on them.
Since I live in the Sonoran Desert, all the spalting on wood I buy halts the moment it arrives here!
: My take on turning spalted wood is to do it only when wearing a respirator. : You can sometimes get allergic reactions with 'plain' woods - such as the : rosewood family - but the spalting in spalted wood is caused by Fungi and : not something you want to risk getting into your respiratory tract.
That's the common wisdom in woodturning and woodworking. But I did a fairly exhautive search about two years ago -- everything from websites to medical journals -- and turned up essentially no evidence that this is the case. There was an article in the British journal Woodturning by two turners who were also medical doctors, and they argued that the fungal spores are not any more worrisome than any other sort of dust.
I don't mean to discount the common wisdom (which often turns out to be correct!), but I'd like to see more research into the matter -- does anyone have any sources to contradict mine?
From my experience under the Redwoods and now in a Piney forest area - the spalting continues on as long as there is dampness. Sap or damp (water).
Wood here spalts and continues until there is a pile of mush on the ground. I had several large limbs get hung up - mid air - and they dried hard. A tree fell over and hung in another tree, most of it is hard dry but had spalting under the bark.
On Mon, 4 Jan 2010 17:00:46 -0600, Andrew Barss wrote (in message ):
Spalting is the name given to the staining or marking caused by the earlier stages of rot. Like a mushroom, rot is the work of fungal growth. Like a mushroom, the conk or other fungus growth you see on the outside of the tree is the "flowering" or "fruiting" body of the fungus, and it produces the spores which are analogous to seeds from a flower. The fungus grows from spores, just as a flower grows from seeds. It is the spores that you do not want to get into your lungs - same precautions you take in not stirring up the moldy guck in a damp basement or fungus-laden insides of badly vented walls... you don't want to inhale the spores. That said, the fine dusts that we generate as turners can be an irritant to some people. Some people will be sensitized to these dusts, and get allergic reactions. Some kinds of wood have a more pronounced effect than others. There are, in fact, lots of websites out there addressing this specific issue, sensitivity to various wood dusts, by species. Some can be very toxic, in fact. I cannot say which, right now. In my own case, I work with what I get locally, pine, birch, and aspen. Pine and aspen will dry nicely with the bark on. Birch will not. Birch bark is waterproof and will hold the moisture inside, only allowing the wood to dry from the ends, so it rots easily and quickly. On the other hand, it can be turned with the bark on and the inside of the turned objet then permits drying of the wood that may still have a patch of birch bark on it. There is nothing wrong with wearing a decent dust mask. If you want, you could actually vigorously wash the block of wood in question, to remove any loose material that you are uncertain about. I am not a doctor, nor do I play one on TV. These remarks are my own observations and are based on my own reading on the subject. There are no guarantees. In my own case, I'd wash the wood, and get to work. I tied into a piece of birch that was a bit too far gone for my skill level, too many places of soft punky rot in the block, and so it will go into the fireplace. tom koehler
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