15594Re: [MedievalSawdust] Re: Harvesting your own wood
- Mar 1, 2013Microwaving rough, green wood turnings was a 'big discovery' about 10-15
years ago with turners in Australia. Just turn the bowl about 20%
over/under sized, microwave until it steams, leave to cool then finish.
Any warping occurs during the microwaving and can be eliminated in the
subsequent cleanup. Even longer ago - mid 1970's, a friend showed me a
technique he had been shown during his apprenticeship, which was to
basically boil fairly thin green wood in linseed oil for carving pistol
grips - the process stopped the wood from subsequently warping and gave
it a semi-ebonised dark walnut color.
In both cases I think that the heating stabilises or 'locks' the wood's
structure so it doesn't subsequently change.
There is also a process for making super-bendy wood that was a big buzz
a few years ago - basically they pressure cook wood then compress it
longitudinally (ie. with/along the grain) until it shortens a given
percentage. This telescopes some of the cells making the wood go
'floppy'. Chris Schwarz put a few articles on line about the stuff - he
had one piece tied into a knot by hand and made some Windsor chair backs
without having to steam bend it. It is shipped sealed in a plastic
sleeve and when bent to shape and allowed to air dry it 'sets' into
shape, no spring back. I haven't seen anything about it for a while, it
may have been a casualty of the GFC.
Brusi of Orkney
On 02-Mar-13 4:35 AM, Ralph wrote:
> Living in the Pacific North Wet (and here you thought that PNW stood for Pacific North West)... Growing wood is, well, easy. I have trees, I planted that are already 60 ft tall.
> We get lots of wood.
> I once cut down a 50 year old Apple, milled it into boards, that I stacked and stickered. Stacked the wood wood on a pallet, put a pallet on top and used cargo strapping to supply pressure to keep the Apple from bending. I left one piece out. During the drying process it got 30 degrees of twist and about 20 degrees of bend. So I know the Apple that dried under pressure has a LOT of tension in it.
> This winter I again cut a bunch more Madrone Burl, this still mills (or turns) like butter, but splits if you look at it too fast. The cure for this (and some other easy-to-split woods) is boiling. Yup, boil the wood for about an hour per inch of thickness. The failure rate, after boiling, is, well, very low. No one (including Forest Product types) knows -exactly- why this works, but it does appear to relax/release/something a lot of the tension in wood, with greatly reduced splitting.
> I have also processed, well maybe tons of green/wet Maple, Red Alder, Walnut, Butternut, Filbert, Cherry (timber), etc. This wood has been mostly used for turning. Some of the bowls I turn green and let dry, some I rough turn green, dry, and re-turn, and some I have let dry then turn. Some of this splits, but as some great turners say "There is no turning that is so bad it can't be used as firewood"
> But one other thing I do is Microwave dry wood. Yup, get ahold of one of those old LARGE capacity microwaves that everyone used to own and dry wood that way. Depending on how much wood is actually in the oven the cycle might be as low as 30 seconds, or as high as two or three minutes. Let it sit for maybe an hour, and repeat. I weigh the wood just before I do a daily cycle. When the wood stops changing weight, I stop.
> One other thing on checking woods wetness. There is a pencil that many art supply houses sells called "ink in a pencil". On dry wood, it's just a pencil, but if the surface is wet, the pencil "lead" turns blue and stains the wood a bit. When the pencil mark doesn't turn blue, the wood is getting dry
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