# Help with kiln drying...



## Daniel (Dec 12, 2011)

I just discovered that a neighbor down the road about 5 miles has a kiln drying operation... needless to say this is potentially exciting.

I say "potentially" because I am very new to this stuff, and would like to have some input:

1) Is kiln dried lumber desirable? Whenever I have worked with it in rough and finish carpentry, I have been less than impressed. It's actually kind of annoying to work with and doesn't look as nice.

2) Are there some tricks to kiln drying furniture grade lumber that will avoid some of the nastiness of "normal" kiln dried dimensional lumber? I'm thinking about things like (longer) drying times, (lower) starting moisture contents, and so forth...

3) Are there any ways to determine if I should even bother with this idea? 

Again, thanks in advance to the knowledgeable folks here for all the feedback and input.


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## JMC (Dec 13, 2011)

Definitly worth the effort but even after you dry it EMC must be obtained for the peice you are building and it's final home. Of course unless you are putting fixed end caps or permanetly fixed skirts you really don't need to wrry about kiln drying. With big slabs the slower they dry the better to prevent checking/splitting, but if you take a green slab table and put it straight into a conditioned air atmosphere without a good sealing "all sides" you could suffer some severe penalties. JMO


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## Daren (Dec 14, 2011)

Daniel said:


> 1) Is kiln dried lumber desirable?



...Yes if you want your furniture to stay together after it is built and not be full of bugs :yes: That is my smarty pants answer, below is more in depth...

Not saying you can't build with properly air dried lumber (most species) Kiln drying is just faster. I don't know of this ''nastiness'' you speak of when you are talking kiln dried wood, but you did say dimensional (framing) lumber. So the wood was probably nasty to start with, that is why it is framing lumber not furniture lumber.

I use both air dried and kiln dried wood. The desk I am sitting at is air dried walnut, even though I have my own kiln. I was in no hurry and let this particular wood air dry for 2 years before I built anything with it. I could have kiln dried it in 3 weeks and it would look/act the same. Some people (many people) if you are looking to sell wood will not buy it (or at least pay ''full price'') unless it is kiln dried. 

Depending on where you live parts of the country wood just will not air dry to a moisture content that it can ever be brought inside as a finished project. Brought in a heated/air conditioned space it will further dry and pull itself apart. I air dry and kiln dry, I have more degrade (bad stuff happening to the wood) when air drying just because I can't control the weather like I can a kiln.

6%-8% MC is considered ''kiln dry'' for inside furniture. Here is a link that shows a ballpark of what wood will air dry to. http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf
Some guys air dry then bring the wood into a ''conditioned'' space (heated-cooled-dry) to acclimate to where it will be put into service before ever trying to build with it.

I could type more. But my basic thought is if you have access to a kiln, kiln dry.

.


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## Daniel (Dec 14, 2011)

Daren,

Thanks so much for the info!

Can I ask a couple of more detailed questions?

1) How much is a good rate for kiln drying ~500 bf?

2) I've read (and heard) that air drying for a while and then kiln drying to "finish" is a good method... do you agree?

3) Are there any specifics regarding the kiln drying process that I should pay particular attention to, i.e. how fast or slow, how hot or dry the kiln environment is?

Cheers!

Dan


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## Daren (Dec 15, 2011)

1) Price ? It varies regionally. I have heard prices from $0.15 bft to $0.50 bft. Around here it is $0.35

2) I don't totally agree, that is a generality. Specifically it depends on a few things, species and time of year/weather mainly. Light colored species like maple for example milled in spring when it is cool and damp would be best put in the kiln immediately. It tends to stain/discolor if not dried fast, sitting around wet is not good for it. Hot and dry summer it can be air dried first with less problems. Or a species like white oak milled in the hot dry summer is more prone to surface check air drying than if it was put in the kiln right away where drying rates can be controlled, especially thicker stock. Some species like cherry and walnut are forgiving and I see no difference in quality thrown straight from the mill into the kiln than if it was air dried first, so it doesn't matter. On species that can safely be air dried first obviously it takes less to ''finish it'' in a kiln=cheaper for the kiln operator=more profit. And if it is already air dried, from air dried to kiln dried it is hard to screw up wood=less risk for the kiln operator. Those last 2 points are probably where the generality that it is best to air dry first came from.

3) I don't understand the question as asked. Are you running the kiln ? What kind of kiln, solar--dehumidification--conventional--vacuum...I thought some other guy was from reading your first post, if so drop it off/pick it up when he says it's dry and pay him. In the mean time let him worry about it.

.


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## Daniel (Dec 15, 2011)

Thanks!!

Re: 1) Check!

Re: 2) Check!

Re: 3) It will be taken to a kiln, so I will talk it over with the owner/operator... but basically not my problem so much.

Cheers!


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## Mandolin (Jan 3, 2012)

Daniel, I live in the deep south, and I mean DEEP. My biggest problem with air drying here is humidity. It gets high here in the summer. I can usually air dry lumber down to about 12-15%, but with pine, which I mill the most of, will usually stain. If there is no big demand for it at the time, I will usually air dry it for about a month, them load it in the kiln. My controller is simple. Two switches for the blowers, a smaller control panel for the dehumidifier unit and a control for the aux heater. The water comes out the bottom and if you want to be scientific about it, you can weigh it each day and use a complicated algebra formula to figure out how fast it's drying. I usually just look at it every day and compare it to what was in the catch pan the day before. At the end of the cycle, I open the vents and just let the blowers run for a day or two. To me, this conditions the wood and, for lack of a better word, settles it down and relieves any remaining stress. I basically dry hardwood the same way, but just watch it closer.


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## Daniel (Jan 3, 2012)

Mandolin said:


> Daniel, I live in the deep south, and I mean DEEP. My biggest problem with air drying here is humidity. It gets high here in the summer. I can usually air dry lumber down to about 12-15%, but with pine, which I mill the most of, will usually stain. If there is no big demand for it at the time, I will usually air dry it for about a month, them load it in the kiln. My controller is simple. Two switches for the blowers, a smaller control panel for the dehumidifier unit and a control for the aux heater. The water comes out the bottom and if you want to be scientific about it, you can weigh it each day and use a complicated algebra formula to figure out how fast it's drying. I usually just look at it every day and compare it to what was in the catch pan the day before. At the end of the cycle, I open the vents and just let the blowers run for a day or two. To me, this conditions the wood and, for lack of a better word, settles it down and relieves any remaining stress. I basically dry hardwood the same way, but just watch it closer.



Thanks the for advice/input, Mando. I've been to Mississippi in the summer (an ex girlfriend was from Laurel) and it just about killed me. I'm based in Syracuse, NY and come from central Maine - air drying is a bit more forgiving and easy up here. The lumber we've just sawn is going to air dry for a while and perhaps go into a kiln come April or May... unless someone wants it KD right now! I can afford to wait a bit, and it seems that in my climate, and with no need to rush, I can be patient. I am going to either set up or hook up with a kiln operation, eventually. Cheers!


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