split bowl

[crazylegs]

how do you know when a blank it dry? I have just made a bowl out of spalted wood. It has sat in my garage for at least a year. I was pleased with the result as its a new hobby for me but after two days indoors it split. The wood seemed dry but had a few small splits at the ends which I cut off . It was about 8" long by 5" and I cut it in half and turned a small bowl. Might be a stupid question but where did I go wrong?

[bodrighywood]

Depends what you mean by dry. It can seem dry in your workshop but if you have  central heating then it is going to dry out a lot more and quicker hence the splitting. You can get a moisture meter which whilst not dead accurate will show some interesting factors. I have kiln dried wood that originally came in at 4% when I bought it for a commission and has risen to 8% in my workshop over winter. Also different woods will dry quicker with a bigger chance of splitting. When I moved from Cornwall to Wiltshire one or two pieces of yew that I had had for some years split within weeks as the climate was much drier. Whatever you get told it is more art than science a lot of the time. Ideally get your moisture content down to below 6% but don't guarantee it'll stay there.

Pete

[Paul Hannaby]

They say you should allow a year per inch of thickness for air drying wood and that this doesn't hold true for particularly thick pieces either so a year for your piece was no where near enough.

What most people do is to rough turn to reduce the thickness of what needs to be dried, allow it to dry knowing the wood will go out of shape and then re-turn to the final thickness. this way, you can generally reduce drying time to a few months.

In answer to your question about when is the wood dry - the answer is never! It equalises to it's environment and you can figure out when that has happened by weighing the piece of wood and when it stops changing weight, it has equalised. Move the wood to a different (wetter or drier) environment and the wood will either absorb or lose moisture, which will result in a change in weight and possibly a change in shape too.

[crazylegs]

thanks for the replies. They have helped a lot. So a 'dry' ready to turn blank bought on the internet could equally be a problem as you have no idea of the conditions it was stored in?

[Paul Hannaby]

"Dry" is like the "how long is a piece of string" question. It means different things to different people! Apart from that, a badly dried blank might be no use anyway so choose your suppliers carefully.

[BrianH]

And just when you thought you were getting to grips I come along and point out that not all movement/cracking is down to drying. Trees grow with different stresses and strains built in (heavy boughs to support, windage to counteract etc etc). When we come along and cut through these stressed areas we risk interfering with the internal balance of forces and movement occurs. Platters becoming rocking horses are the most obvious example.
All the best
Brian

[Schurchy]

*** FYI  and Safety Advice ***
We were warned at our last club meet about the dangers of turning Spalted wood but particularly 'green' spalted wood. I must admit I hadn't thought about there being too much difference but with 'green' spalted wood the spores in the fungus are still living and growing and therefore have an even more detrimental effect if inhaled than when in 'dead' dust form from seasoned wood. The spores continue growing in the lung which can eventually cause death as it's not treatable. Obviously we should all be using dusk masks anyway, but beginners should be made aware and not such beginners should be reminded of the dangers.

If I have any of this wrong, its just what our demonstrator told us so please correct me where necessary.

[Paul Hannaby]

*** FYI  and Safety Advice ***
We were warned at our last club meet about the dangers of turning Spalted wood but particularly 'green' spalted wood. I must admit I hadn't thought about there being too much difference but with 'green' spalted wood the spores in the fungus are still living and growing and therefore have an even more detrimental effect if inhaled than when in 'dead' dust form from seasoned wood. The spores continue growing in the lung which can eventually cause death as it's not treatable. Obviously we should all be using dusk masks anyway, but beginners should be made aware and not such beginners should be reminded of the dangers.

If I have any of this wrong, its just what our demonstrator told us so please correct me where necessary.

I'm afraid your demonstrator is misinformed. For a normal healthy person, the fungus spores present no danger. Dr Sarah Robinson of Oregon State university has done extensive research on the subject. There are various articles online written by her. Perhaps you should point your demonstrator in her direction.

[Schurchy]

I'm afraid your demonstrator is misinformed. For a normal healthy person, the fungus spores present no danger. Dr Sarah Robinson of Oregon State university has done extensive research on the subject. There are various articles online written by her. Perhaps you should point your demonstrator in her direction.
[/quote]

Hi Paul, many thanks for the correction. It did come as a bit of a surprise at the time but also seemed quite plausible.

[Wood spinner]

Its not worth the risk , mask up on all occasions 

[Paul Hannaby]

Wearing respiratory protection against wood dust is always a sensible precaution but it you think about it, the fungus spores in question are always in the air anyway (not actually in the wood).

[bodrighywood]

Pretty much every type of wood has potential side effects for someone so as Paul says decent respiratory protection is advisable. Google 'wood toxicity'

Pete

[beyond23]

i agree