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post #1 of 15 Old 11-16-2012, 03:54 PM Thread Starter
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moisture content

i use rough cut pine to make outdoor furniture, in the past i would allow the wood to air dry for 3 months then take to the kiln where it is dried to 6% moisture, however when i bring it back home the content goes up to 12-14% which is normal for my area. my recent load of lumber has been sitting for 3 months and the moisture check is 13% so i am wondering do i still need to have it dried at a kiln or is it ok to use as is, i am worried about the wood spilting or warping if it isn't taken to the kiln, this lumber is 1 1/4 planed to 1"
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post #2 of 15 Old 11-16-2012, 05:08 PM
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Originally Posted by chairguy View Post
i use rough cut pine to make outdoor furniture, in the past i would allow the wood to air dry for 3 months then take to the kiln where it is dried to 6% moisture, however when i bring it back home the content goes up to 12-14% which is normal for my area. my recent load of lumber has been sitting for 3 months and the moisture check is 13% so i am wondering do i still need to have it dried at a kiln or is it ok to use as is, i am worried about the wood spilting or warping if it isn't taken to the kiln, this lumber is 1 1/4 planed to 1"
Wood will expand and contract to moisture conditions. Once acclimated there isn't a drastic change for where it will remain. An example, if your working wood was 13%, and then you took it to an area where it will dry further, the possibility for shrinkage would be greater. Likewise if it is at 13%, and gets exposed to an increase, the wood will expand.

I wouldn't get it kiln dried at this point. If your working conditions are relatively the same as where it will be going (outside). Kiln drying does kill little critters though.





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post #3 of 15 Old 11-16-2012, 05:37 PM
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You don't have to have it kiln dried, but three months air drying won't bring your wood down to 13% I'm actually surprised the kiln is even bringing pine down to 6, they typically stop around 12%. If it's going to wind up there anyway why don't you just have the kiln bring it down to 13% and save a little money?
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post #4 of 15 Old 11-16-2012, 05:56 PM
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Doesn't sound to bad.
It's going to sit outside, so it's going to get wet anyway. It's not so much the MC, it how you compensate for it. As far as joinery, or metal fasteners. ie......lag bolts, screws or nails.

When it's rustic......it's rustic
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post #5 of 15 Old 11-16-2012, 05:59 PM Thread Starter
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actually i was pretty suprised that the moisture was down to 13% after only 3 months, once the chairs are made i use sherwin williams woodscape stain to protect against the rain, i never considered it before but this stain should prevent moisture absorbsion to a degree how much i can't even guess
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post #6 of 15 Old 11-16-2012, 11:34 PM
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Air drying in a dry place will easily bring 1 inch pine and even most domestic hardwoods down to 12% moisture in equilibrium with 65% humidity in a 2-4 months. Some harder(more dense) hardwoods take a bit longer.
Kilns that do softwood for sale or export just get it down to such levels. Hardwood for indoor furniture is dried to 6% or so. If it is left outside for a few weeks or a month or so, it will go back up to equilibrium at at the 12%.
There is no benefit to using a kiln unless you are in a hurry like those in the furniture business are as they don't want to store the wood that long. A hot kiln can alter some of the properties of the lignin etc in wood but this has little applicant unless your want to bend the wood. It destroys some of its heat plasticity..
No finishes alter the final moisture content though they can slow down the equilibration time. Thick wax is most effective. Epoxy is pretty good. Urethane slows a bit. Most oil finishes don't alter the time much. Water combines with the cellulose and expands it as the moisture level increases up to about 20 % . Above that its wet,free water and subject to molding.
Outdoor furniture is pretty stable if its not allowed to stay wet. The outdoor relative humidity is fairly stable winter and summer..
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post #7 of 15 Old 11-17-2012, 01:08 PM
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I never realized softwoods air dried that fast. Good to know.
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post #8 of 15 Old 11-18-2012, 10:10 AM Thread Starter
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i do not plan on using this wood for maybe another 3 months or so, with that in mind and the info i have received from this forum i think i will restack the wood where i normally store it outside next to my garage covered with a tarp, uncovering whenever weather permitting, this will be the first load i use that has not gone to the kiln and see if there is any difference, i guess my main concern is the paddle arms on my chairs that they do not warp as they are 6" wide, thanks to all who have shared thier knowledge and experience
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post #9 of 15 Old 11-18-2012, 10:37 AM
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Be sure if you plan to paint the wood you find primer and paint to handle the conditions. I had some adirondak chairs for a few years outside then decided to paint them, moisture and wood movement conspired to chip most of the paint off in a matter of months.
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post #10 of 15 Old 11-18-2012, 11:47 AM Thread Starter
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no paint 3 coats of spar urathane, , because the spar takes so very long to do as i coat every piece with 3 coats prior to assembly but it has held up for 3 years so far, but switching to sherwin williams semi transparent wood scape stain
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post #11 of 15 Old 11-18-2012, 01:00 PM
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Setting the pitch in the pine is something to consider as well. Don't want that running all over the place. I'd go to the kiln.
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post #12 of 15 Old 11-18-2012, 01:35 PM
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I don't know if this has been brought up but 13% skin moisture is not the same as internal.
You have to cut into it to find out internal.
If your wood only sat for 3 months from semi fresh cut, ain't no way it's at 13% internal unless it was sitting in the hot summer sun.
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post #13 of 15 Old 11-18-2012, 02:37 PM
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If well stickered and in a place with good air circulation, it should Dry well all the way through. I dry mostly hardwoods using a shed or spare garage. I have a very small oscillating fan on the pile do to improve air movement. I measure with a pin style meter and the cut a piece to confirm the interior.
2 inch wood takes quite a bit longer but I inch dries pretty fast.
It is correct that the best time is late spring early summer to get some warm dry air and a bit of solar heating to the shed. Sometimes the logs have been cut in winter when most dry. otherwise I try to cut in spring before trees fill with sap and move the air dried wood into the heated house/shop wood room in fall before colder weather and snow. 1 inch stuff is ready by new year at below 8% and often below 6%. If you were doing outside projects the wood would be ready after 2-3 months air drying over the summer.
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Get the initial wood fast dried to avoid sticker stain and surface mold staining. The free water can be dried fast but once it is gone, the risk of splitting is high if you try to dry too fast especially if you don't put some kind of end seal like pentacryl white glue or any of the other favorites. I use pentacryl but any white or yellow glue that is getting past its best before date gets used. It's easiest if you can do the log ends before milling. In a pinch a few coats of the ends of a latex paint can can be used.
The free water is gone when the boards feel dry. The weight of a board is a useful indicator. Most of the water is free so the weight will drop quite a bit. Some wood is more than 100% wet or put differently the free water is more than 50% of the weight.. Red and white pine sapwood is about 130-150% moisture content.
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post #14 of 15 Old 11-18-2012, 03:10 PM Thread Starter
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when the wood was cut the content was 26, when i checked it this week i made a cross cut about 4" back and it was 13. this was one of the top boards when i restack i will cut and check a lower board, as far as the pitch goes i have only ran into a couple of strong sap viens that when removed was 3 to 4 inches wide, about 1 board per hundred board feet so that is not bad for waste
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post #15 of 15 Old 11-18-2012, 05:55 PM
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I air dry mostly hardwood and use a shed and part of a garage. If it is properly stickerd and kept in a dry place with good air circulation, 1 inch wood will dry to equilibrium over a few months. I use a small oscillating an. It is important to have lots of airflow until the free water is gone. There is no movenment issues until then.. Red and white pine sapwood have over 130-150% moisture. The weight of a board is a good indication. The surface also feels dry. Getting the surface dry quick avoids sticker stain and surface stain from mold.
It is correct that the process works best with the warm to hot drying air if summer but never the kind o f heat of a kiln. Kiln drying is usefull to speed up drying for commercial uses. It avoids having a lot of storage space. Be carefully about a lot of "kiln dried" wood that is stored outside in sheds as it will quickly reequilibrate to the usual 12% outside moisture content.
I tend to use winter logs or cut in spring before the sap gets in the wood. The wood will be down to equilibrium at about 12% using a pin meter ans also cutting a piece of wood. I move the wood into the heated house, wood room in the fall and it is ready to use at below 8% by new year.
If you are making outside furniture or projects, then the 12% is a good level to work with.
2inch wood takes a few months longer. I will tent to use it the next year.
I DO use a moisture meter and check at least several inches from an end in the middle of the board.
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