Kiln dried, Air dried
- Thread starter MIGNAL
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Hey Mingal
I have just made some furniture with 20 years air dried elm. Because it wasn't kilned dried it was more prone to woodworm so had to treat it all with a pesticide which takes 5 days to dry. built a coat rack with it after one week in a central heated house the wood shrank about 5mm this pulled 4 joints apart because they were connected to a metal band that didn't change size.
In the process now of building a kiln to dry the rest of it as i have 15 cubic foot of it and is worthless to me if its not dry stable. If you have aired dried timber and have space to leave it in your house or a heated shop for a few weeks before using you should be grand. my shop is an ice box unfortunately.
Regards Rick
I have just made some furniture with 20 years air dried elm. Because it wasn't kilned dried it was more prone to woodworm so had to treat it all with a pesticide which takes 5 days to dry. built a coat rack with it after one week in a central heated house the wood shrank about 5mm this pulled 4 joints apart because they were connected to a metal band that didn't change size.
In the process now of building a kiln to dry the rest of it as i have 15 cubic foot of it and is worthless to me if its not dry stable. If you have aired dried timber and have space to leave it in your house or a heated shop for a few weeks before using you should be grand. my shop is an ice box unfortunately.
Regards Rick
Elm is one of the worst - 45yrs ago at school I saw a board that was about 12' x 14" x 1 1/2" that's ends were near 180 degrees to each other - I dread to think how much it distorted in other directions.
I've not heard the bit about woodworm resistance, though.
I've not heard the bit about woodworm resistance, though.
Sgian Dubh
Established Member
There's probably a lot more than you planned to read on that subject in this old thread MIGNAL: air-dried-v-kiln-dried-t32802.html Slainte.
I would say the basic difference is is moisture content, air-dried timber has 15-18% of moisture, which is suitable for outdoor projects, kiln-dried timber should have 8-10% and that's the wood for furniture and cabinets. That's it.
Frank
Frank
Thanks for the replies. I was curious to know if air dried worked better/easier with hand tools.
I'm fairly certain that 90% + of the timber that I use has been air dried. It is conditioned in the workshop for a further 2 years +, so I doubt that MC is much of a factor. I've just bought some straight grained QS kiln dried Cherry so I'll see how that works. I suspect/hope that it will be fine.
I'm fairly certain that 90% + of the timber that I use has been air dried. It is conditioned in the workshop for a further 2 years +, so I doubt that MC is much of a factor. I've just bought some straight grained QS kiln dried Cherry so I'll see how that works. I suspect/hope that it will be fine.
Yes, air dried works better with hand tools and tears out less! And so long as it is properly dry you will be fine.
My experience is that air dried comes into the workshop at maybe 15%, but if the workshop is warm and dry, and you leave it to acclimatise in there first, it will go as dry as you want — 8% no problem. Given that I don't see a problem with using it for furniture. It's not like the 8% that the kiln dried arrives at is somehow fixed — leave it outside in a less than dry shed or workshop and it will soon be at 15-20% and you will then get all the problems you might expect with air dried if you make something with it in that state and put it into a centrally heated house. I'd say it's about making things using timber at a sensible moisture content, whether air dried or kiln dried.
I think that kilned timber does move a little less, it is affected somewhat by the drying process, but it still moves plenty with big humidity swings. And air dried is SO much nicer to work with a plane, and you get less tear out generally.
I don't believe that air dried is especially susceptible to woodworm or needs to be treated before indoor use, so long as it is brought down to a sensible moisture content first. I've used air dried on loads of pieces of furniture and never had a problem or complaints, but I do make sure it's dried properly in the workshop before I use it.
I'm always surprised at the elm comments; I've used air dried elm several times and never had any movement problems at all. It does tend to deform a lot when it is being dried from green, so the boards can be a bit wonky when you get them, but once it is dry I've never experienced it moving excessively in normal use. In fact I have a table top made from really wild elm that I made years ago when I was learning; it's in an outdoor timber store, open on one side and has been for a couple of years and it's as flat as the day I made it.
Anyway, sorry to be contrary, but that's my two cents!
My experience is that air dried comes into the workshop at maybe 15%, but if the workshop is warm and dry, and you leave it to acclimatise in there first, it will go as dry as you want — 8% no problem. Given that I don't see a problem with using it for furniture. It's not like the 8% that the kiln dried arrives at is somehow fixed — leave it outside in a less than dry shed or workshop and it will soon be at 15-20% and you will then get all the problems you might expect with air dried if you make something with it in that state and put it into a centrally heated house. I'd say it's about making things using timber at a sensible moisture content, whether air dried or kiln dried.
I think that kilned timber does move a little less, it is affected somewhat by the drying process, but it still moves plenty with big humidity swings. And air dried is SO much nicer to work with a plane, and you get less tear out generally.
I don't believe that air dried is especially susceptible to woodworm or needs to be treated before indoor use, so long as it is brought down to a sensible moisture content first. I've used air dried on loads of pieces of furniture and never had a problem or complaints, but I do make sure it's dried properly in the workshop before I use it.
I'm always surprised at the elm comments; I've used air dried elm several times and never had any movement problems at all. It does tend to deform a lot when it is being dried from green, so the boards can be a bit wonky when you get them, but once it is dry I've never experienced it moving excessively in normal use. In fact I have a table top made from really wild elm that I made years ago when I was learning; it's in an outdoor timber store, open on one side and has been for a couple of years and it's as flat as the day I made it.
Anyway, sorry to be contrary, but that's my two cents!
custard
Established Member
marcus":2wspdddm said:
Marcus, I'd make a few points,
1. Many workshops aren't warm and dry, I'd guess that even heated and insulated workshops aren't as dry as most home interiors. Right now the moisture meter in my (heated and insulated workshop) reads 54% while the moisture meter in my house reads 45%.
2. Given the conditions in many of the workshops I've seen I'm not sure stored timber would ever get down to 8%.
3. How much workshop space can be given over to storing timber while it acclimatises?
All good points, and to be honest I use kiln dried if I need to get the job out quickly. I would always use air dried all things being equal, but sometimes you can't beat the convenience of kilned.
Storage space is less of a problem if you break the timber down into 'almost there' dimensions as soon as you get it in, and it dries quicker like that too. And I'm lucky enough to have a nice toasty workshop!
Storage space is less of a problem if you break the timber down into 'almost there' dimensions as soon as you get it in, and it dries quicker like that too. And I'm lucky enough to have a nice toasty workshop!
matthewwh
Established Member
Couldn't agree more, air dried is so much nicer.
You can accelerate the change in moisture content with kilning, but there's more to it than just moisture content.
Free range (air dried) wood has been through the humidity cycles of the seasons, it is relaxed and happy and wants to be worked. There is no embrittlement, even when it is really dry.
Obviously there are practical limitations and sometimes you have no option but to use kilned, but don't confuse the hamburger with the fillet steak.
You can accelerate the change in moisture content with kilning, but there's more to it than just moisture content.
Free range (air dried) wood has been through the humidity cycles of the seasons, it is relaxed and happy and wants to be worked. There is no embrittlement, even when it is really dry.
Obviously there are practical limitations and sometimes you have no option but to use kilned, but don't confuse the hamburger with the fillet steak.
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