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Fresh Cut wood Drying tips needed

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Forum topic by MrWizard posted 1391 days ago 10300 views 1 time favorited 12 replies Add to Favorites Watch
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MrWizard

145 posts in 1430 days


1391 days ago

I have read about the drying methods for different woods and how to get your self set up to dry your supplies. My question is this; Is it better to leave the wood in LOG form or cut it into the desired sizes and shapes and then cure them that way.
I know it should seem obvious to most but I thought it was worth asking. I’ve seen drying sheds and the boards are 15-18 feet long, But the work I’m doing is on a much smaller scale. Just looking for insight.
Thanks


12 replies so far

View Jonnyfurniture's profile

Jonnyfurniture

59 posts in 1453 days


#1 posted 1391 days ago

The center of a log can only shrink so much. It’s inner rings circumfrences are less than the outer ones so the total shrinkage for any ring closer to the center will be less than the outer. Add to that some faster drying for the outside of the log because it is next to the air and you have the conditions to make splitting and checking which renders the wood unuseable. Cut it into boards 1/4 inch larger than you need and sticker every two feet. Leave it long as you can.

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shipwright

4900 posts in 1424 days


#2 posted 1391 days ago

I built one of these very quick and dirty. http://www.woodweb.com/knowledge_base/Solar_Kiln_Designs_2.html Total cost of two box fans and a timer. The rest was used wafer board that I salvaged from a roof and some roll plastic I already had. It is very efficient – mine does about 120 fbm at a time. The important thing is If you don’t have a full to capacity kiln, you have to reduce the collector area or you’ll risk overcooking it. Mine resembles #1 in the article.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

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Gofor

470 posts in 2413 days


#3 posted 1391 days ago

From personal experience: The wood will not dry in log form. I have cut into small (12”) diameter logs that have been setting for 5 years and the center is still wet. I have salvaged walnut heart from trees downed 15 years ago in a hurricane, and it was still wet.

Seal the ends so that moisture escaping from the capillary grains slows down to the rate that it is escaping from the sides, or it will split. Some people use latex paint, which I have not had much luck with, or a wax-based end-grain sealer like anchorseal which I use. This is best applied as soon as possible after the tree is felled.

Depending on the species of wood, it will need about 6 months to a year per inch thickness of air drying (protected from sun and rain and with spacers between slabs) before it is ready to move into the shop. After initial milling to smooth the sides, etc, it may need a couple weeks or more to dry and quit moving (warping).

The trick initially is to let the moist fresh cut wood dry slowly enough so that the moisture readily escaping from the exposed surfaces does not evaporate faster than the moisture can move from the inside wood to the outer surface. If it dries too quickly, the outside layers of wood are dryer and want to shrink without the moisture in the cells. However, it is prevented from shrinking in size because the inner wood it is attached to is still loaded with water. So, the outside wood splits to relieve the stress.

In log form, the outer wood is initially protected by bark. As the bark drys, it cracks off, letting the outside layers dry too quickly, and it starts splitting in from the sides. The cut ends dry quickly because they are used to letting the moisture (sap) run through them, so also will split. This is if you have them off the ground. If not, the bugs have already invaded under the bark and will keep it moist so they can devour it. Seemingly contra-intuitive , though, the best way to preserve logs is to submerge them in fresh water and mud, where they can last for years undamaged.

Now, saying you do it all perfectly, then you may still have the results of what the tree went though while it was alive and growing. If on a hill side or subjected to a lot of wind, it built up a lot of strength in some spots to counteract the environment. This will result in some layers of wood being a lot denser than others.. After perfect drying, the internal stress of the different densities can still cause the wood to split where the higher/lower density wood meets. This is usually called wind shakes. Nature of the beast and nothing you can do to prevent it and impossible to determine ahead of time unless you were there to drop the tree and were able to deduce the hazard. (That is why some sawyers like to go deep into the woods on flat ground to get the prize tree).

And then there is case hardening and other defects caused in a kiln drying process where the temperature is not regulated enough to allow the internal stresses to be relieved before further drying. To complicate things, different species dry at different rates and have different vulnerabilities.

Personally, I follow Johnnyfurniture’s method, but sticker at about 16” (put a row of spacers, all the same thickness of 1” between boards all directly over the ones in the layer below. The spacers are called “stickers”). Putting a strap around the stack for longer boards helps reduce twisting and warping of the top boards, or weight (a lot of weight) can be put on top. I strap close grained woods like cherry, sweet gum and maple, all prone to twisting and warping.

If the bark is tight on your logs, wait for cool weather (which is now fast approaching or may be already here in your area) to slab them out. The moisture loss rate from the initial cut (anywhere from 35 to 50% moisture content) until you get it down to 20% is when most the damage happens, and cooler weather slows the rate of moisture loss. After you get it down below 15%, then the rate can be faster (stick them in your attic, for instance, or consider kiln drying). Cutting them and immediately bringing them into a heated/low humidity shop in the winter is probably not your best choice.

Although 7% is considered the optimum for furniture making, I have used 12% wood, letting it set a couple days after the initial rough dimensioning for my project, so that it can finish moving and dry a bit more, with good results. My shop is not climate controlled, and my endeavors are mostly used by family that does not have central air-type climate controlled homes, so 7% is a moot point in my high humidity environment.

My stated moisture content percentages are based on a cheap and less than reliable moisture meter, tho, so take them with that caveat.

Good Luck. I am an amateur at this and the above is based on about 5 years limited experience and trying to find out what I did wrong. 5 years is not long considering it takes a couple years to find out you messed up. My initial woods were green cut from sawyers, I now am milling some of my own with a chain saw mill, so still have a lot to learn. Most of the info I received from sawyers who do this professionally.

Go

-- Go http://ncwoodworker.net/pp/showgallery.php?cat=500&ppuser=730

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LaPala

21 posts in 621 days


#4 posted 591 days ago

Thanks for the rich information in LJ. (1st post, so forgive me if this is the wrong section or reviving such an old post is not encouraged.)

I scored an Angsana tree (http://en.wikipedia.org/wiki/Pterocarpus_indicus) today and was wandering how to dry it for future use. Second load which will be the main trunk coming tomorrow. Now I know it’s better for me to rough mill it to size b4 storing and wait for it to dry. Coldest day here is 28°C, so I guess I just have to be patience and not have to build a solar kiln. Any other advice fellow LJs can share about this? I would mainly like to dress these logs into wide boards and keep the branching stumps and highly snarly parts for carving.

1st load dumped in front of my house, upper 2/3 of the trunk and the bigger branches

The main trunk half way thru felling. Yes, It’s an urban wood.

-- Make love with wood.

View bondogaposis's profile

bondogaposis

2480 posts in 977 days


#5 posted 591 days ago

Logs will check. Milling logs into boards minimizes checking and shortens drying time. Seal the ends and stack and sticker for best results.

-- Bondo Gaposis

View LaPala's profile

LaPala

21 posts in 621 days


#6 posted 591 days ago

Thanks for the confirmation Bondo.

-- Make love with wood.

View pintodeluxe's profile

pintodeluxe

3320 posts in 1439 days


#7 posted 591 days ago

Mill green lumber
Stack and sticker on a firm, level base (outdoors but covered)
Leave it alone for 1 year per inch of board thickness
This will drop MC to 12-15% depending on climate
Finish in a home dehumidification kiln for 1-2 weeks
This will drop MC to 6-8% which is ideal for indoor furniture.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View SteviePete's profile

SteviePete

224 posts in 1929 days


#8 posted 591 days ago

You might want to take a flyer on greenwoodworking. Chairmaking makes use of natures forces to keep joints tight and learn some skills not used much any more. Split with axe or froe, smooth with axe, knife, chisel, gouge then finish with lathe or scrub plane. Some good tutorials in LJ blogs. Drill holes, fit pieces —may need some “adjustment or mulligan” nature sometimes hard to predict. On Wisconsin! Steve

-- Steve, 'Sconie Great White North

View ToddJB's profile

ToddJB

1936 posts in 756 days


#9 posted 591 days ago

Stickering? Does that mean put the date on it that you laid it up to dry?

-- I came - I sawed - I over-built

View LaPala's profile

LaPala

21 posts in 621 days


#10 posted 590 days ago

Thanks for the figures Pinto.

Stevie, this is the main trunk piece delivered today…

For Angsana the grain is typically interlocked, sometimes wavy. The wood is often marked with little twisted curls and knots which give a pronounced fine figure. Flat sawn surfaces are reported to have a flame figure, and quartersawn surfaces usually exhibit a ribbon figure. Is it still possible to apply greenwoodworking techniques on one this size and grain type? If I remembered correctly, I saw a Roy Underhill video on greenwoodworking and he did mention to use wood with relatively straight grains in order to split it more predictably. Is there a special technique one can use for interlocking and wavy grains? I am also quite frugal so I would like to avoid waste as much as possible.

Todd, by stickering they meant spacers. The wooden spacers are termed stickers.

-- Make love with wood.

View SteviePete's profile

SteviePete

224 posts in 1929 days


#11 posted 561 days ago

Not around crotches or branches, or branch wood for that matter. Yes, must be straight grain. I have used maple red 2-3 inch, ash black and white, hickory- both types. American hop hornbeam, elm white and red and walnut/butternut—always seem to get squirlly grain. Others have said white oak, I have lots of red oak dried but the green stuff smells like fresh puke-not so good. I have some yellow birch chunks I’ll be trying frozen – difficult to stay on the strait grain. Making a new froe from 3/16×2 3/4 O1 tool steel. Old guy said not to make it too sharp. Sharp works like an axe. I’ll post some pics of chairmaking/dog sled/snowshoe work when they find me. Good Luck. On Wisconsin Steve

-- Steve, 'Sconie Great White North

View pintodeluxe's profile

pintodeluxe

3320 posts in 1439 days


#12 posted 561 days ago

Todd,
Stickering means to use uniform strips of wood or stickers to allow air to circulate around each board. Typically they are just 3/4”x3/4” strips of hardwood or plywood used every 2-3 feet to keep the stack even.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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