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Thread: Tips for seasoning wood

  1. #1

    Tips for seasoning wood

    Hi everyone,

    This is my first time seasoning green wood. It's for my bench project, which seems far off at the moment, but I have to start somewhere. The wood came from a birch tree that came down during the winter. I suppose that's beneficial, as it will be slightly on the dryer side. But I hewed the logs, and split them in half. The ends have already been painted with multiple coats of latex paint. Some ends got an epoxy floor paint coating--but for others I just used the latex.

    Anyway, right now the slabs are sitting in my unheated garage, propped up on some 4x4s. I was looking at the slabs the other day, and I noticed that on one or two pieces I'm getting some stress cracks/checks. It's not from the end's drying out, I don't think. I think what's happening is that when I hewed the logs, I naturally squared some of the logs' bows. So the pith is probably still in that section. This section also has a fair amount of knots.

    My plan was to rough out the slabs into my leg and stretcher pieces, cutting out these checked areas (since there's a lot of knots anyway), in hopes that the checking doesn't travel across the board. Then, I'd sticker these pieces individually. Does this sound like a good idea? I'm not sure, though, if it's best to let the boards sticker in as long of pieces as possible to minimize bows or twists?

    Also, are there any tricks to minimize cupping, so I can save as much thickness of wood as possible (I'm thinking of my bench top here specifically). If the cupping happens mainly because the outer layers of the wood are drying faster, would it be a good idea to keep the bark side close if not on the concrete floor for some time, so the drying is balanced out? Or is there really no way to slow down or avoid the outer layers from drying faster?

    Any help is advice is appreciated.

    Thanks,

    Joe

  2. #2
    No wood dryers on here? Come on, I know there must be one or two, haha.

    My main question is would it be better to cut the green slab into leg and stretcher sections, leaving a few inches longer to allow for checking, or to leave the slabs whole and cut it up when it's dry? I don't want the stress and cracks in some parts of the slab to travel throughout and potentially ruin the whole piece, so I'm leaning to cutting it up roughly now.

    Joe

  3. #3
    Join Date
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    I am no wood drying expert. But my general understanding is that the smaller the pieces, the quicker they will dry. Also the smaller the pieces, the less stress they should have and therefore less checking. Professional wood driers often weight down stacks of wood they are drying in an attempt to help prevent excessive movement. Also I would get rid of the pith ASAP. It's going to move and is generally the least stable bit of the log.

  4. #4
    Join Date
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    When you say you split the logs in half - did you remove the pith? Do that if you haven't. Pith being in the wood will promote cracking.

    I'd also recommend you cut them a bit oversize of final desired thickness, rather than leaving them in log form. They'll dry faster and will be easier to cut to size now. If you want 16/4 ready to work wood, cut them around 18-20/4 - depending on species. That will give you room for movement and final jointing/planing.

    Stack and sticker them. Put a sheet of plywood on top and put weight on the plywood to prevent cupping. The usual rule of thumb is 1 year per inch to dry plus 1. Which means 20/4 could take up to 6 years to dry - but the thicker the wood, the harder it gets to predict. I've dried 8/4 and it took between 2 and 3 years to be furniture dry.

    Maybe look into building a electrically powered or solar powered kiln. I've been meaning to do the same.

    Not an expert, but have done this some and want to make my own kiln.


    Gary
    Where did I put that tape measure...

  5. #5
    Join Date
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    Weighting them down may help things out. I would not suggest laying a face directly on the concrete floor, always have an equal amount of air flow above and below each peice. Air drying can be tough and sometimes disheartening. There are some trees that just will not cooperate no matter what precausions you've taken. I also agree that the pith needs to be taken out or that board will most likely not survive the long proccess.

  6. #6
    Thanks for all the advice.

    I'm going to make sure there's no pith remaining, and I'll cut the legs and stretchers out of the slabs before I let it dry.

    I was curious, though, if there's anything that can be applied to the slabs that would balance out the drying or make sure it doesn't take place too rapidly. I've coated the ends with many coats of latex paint, but other than that, I wonder if it would pay to coat the bark side with anything, or the bark side at the ends of the boards, to balance the drying with the center? I read somewhere about creating a mixture of salt, water, borax (for fungal growth, I guess), and some other stuff and applying it onto the wood.

    The reason I'm thinking of such measures is the size of the slabs I have right now are pretty close to the dimensions (thickness mainly) that I'm hoping to end up with. For instance the slabs I intend to use for my top are around 3 3/4" to 4" thick, and I'd like to end up with a top that's around 3 1/4 - 3 1/2". I know that might be very hard to accomplish, but I'd be willing to slow the drying time down in order to try to keep more of the wood.

    Has anyone successfully done anything along these lines?

    Joe

  7. #7
    Wax is usually a better choice than latex paint. You can wax the ends and the face if you wish, but this will slow down the drying process.

    I dry a decent amount of green wood for turning, and I've found that storing split-prone wood in plastic bags or packed in shavings helps regulate the loss (in your case a tarp might work as well). I've found it necessary, though, to take things out of the bag every few days to allow air exchange and to avoid mold. As the wood matures, you can take it out the bag altogether.

    Also, to the extent that you can take the blanks to the basement, do. High airflow and big temp differentials are a killer.

  8. #8
    I have a ssawmill so I dry wood regularly.
    I would break down the pieces as small as you can. I would also support them every 24" maximum.

  9. #9
    Prashun,

    I've tried wax on some smaller cut-offs (which might become planes one day), and I can't get the wax to stick very well. I melted it and tried pouring some on (as the pieces were a little too big to dip them), but it ran all over the place. Then I tried taking a small brush and brushing the liquid wax. Some areas stuck, but a lot pealed right off from moving the pieces around. Maybe I'm doing something wrong, I don't know.

    The wood is black birch, and I don't think it's very prone to cracking. In fact, it's very difficult to split with axes/wedges. Right now, they are in my garage, which isn't opened too often. I have the pieces close to each other, so I think the airflow is minimal. These pieces are 8 1/2' or so, which means trying to bring them into the basement, through the window would be tough. I'm not sure what to do when the warm weather comes around, though. Maybe I'll try a tarp on it, or at least wrap the ends in something to even out the drying somewhat.

    The base of the tree has some spalting in the sapwood, as the tree had a rot spot at the base. The rotted area was cut out, but some spalting remains, so I have to be careful about trying to dry some pieces too slowly.
    Last edited by Joe Fabbri; 03-02-2012 at 3:00 PM.

  10. #10
    Izzy, what's a good height for the spacers? And, to weight the top, would a bunch of bricks spaced every couple of feet work?

    Joe

  11. #11
    Join Date
    Jul 2010
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    Adirondacks, NY State
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    Joe,
    For end coating: http://www.uccoatings.com/products/anchorseal As others have said get the pith out and more weight is better. Every species has an optimal rate for drying. Also the rate will change depending on current moisture content of the wood at the time.


    Regards,
    Charlie
    Last edited by Charlie MacGregor; 03-02-2012 at 4:39 PM. Reason: Links removed

  12. #12
    Join Date
    Oct 2007
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    New Hill, NC
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    Joe, regarding your original question, take a few minutes to read a post that I made a while back. Start with response #6 on this thread:

    http://www.sawmillcreek.org/showthre...ught-yesterday

    That will help provide you with some background on drying wood.

    Many of the ideas that you have mentioned in your posts are not the best ones to use when it comes to drying lumber. Do not tarp your lumber, nor should you dry it in an enclosed area w/o airflow. What part of the country are you in? What is your expected average outdoor temperatures and RH% for the next 120 days? Most likely you should stack and sticker the lumber outside where the prevailing winds can flow through the stack. Your targeted daily MC% reduction will be around .5% - .75% for a 4" birch slab.

    Stickers should be between 3/4" to 1" thick, and made of dry lumber. The closer spaced that they are, the better chance you will have of ending up with flat slabs. I would suggest that you shoot for 16" - 18", no more than 24".

    The best product to use on the ends of the slabs is a commercial end sealer, such as Anchor Seal Classic or Baileys End Sealer. A 5 gallon pail of either will set you back around $80.00

    Typical weight to use on a stack of lumber is 250PSF. So, if you have 24" x 96" of stacked and stickered slabs to weight down, you need to come up with 4000 lbs of weight to place on top of the stack if you expect to yield any benefit from the weight. Some folks have successfully used ratchet straps, tightening down the straps a click or so every week.

    Scott

  13. #13
    Hi Scott,

    Thanks for the link to that old thread. I'm glad you chimed in here.

    I live in Long Island NY. The tree fell down in the winter, sometime in January. I spent a few weeks off and on hewing the log sections. During that time, they remained outside, and it rained and snowed mildly occasionally and was pretty cold. I didn't seal the ends right away as I should have (though I did pile some leaves up against the log ends until I could get to hewing them). So I got some end grain checking. I did wind up freshly cutting some of the ends, though (about a foot in).

    Then, I brought the beams to my unheated garage and sealed the ends with multiple coats of latex paint. Then a week or so later, I split the beams in half. I then left them sitting on 4x4s in the garage, occasionally repainting the ends of the slabs. Right now, it's been cold and raining a lot outside. I expect the temperatures to remain in the 40s and 50s for a while. The garage is fairly large, so it's not in a cramped space, but would you say move them outside nevertheless?

    On another note, just the other day I cut down a cherry tree that broke it's top last year. I painted the ends of the log right away, and the next day I hewed it. It sat outside in the rain for the past few days. I figured that until I can get to sawing it in half it would be better to keep it on the wetter side. Would you say that this was a good thing to do initially?

    Joe
    Last edited by Joe Fabbri; 03-02-2012 at 6:44 PM.

  14. #14
    Join Date
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    Joe, in general it is not a good idea for drying wood to become rewetted. The exception is if the wood is still very green, which it sounds like yours is.

    I would suggest moving your wood outside so that it can start drying. Stack and sticker it where it can get some air flow. Cover the top of the stack to prevent rain from going inside the stack, but leave the sides exposed.

    You took the right tract by cutting off the old, split ends and starting fresh. End checks are similar to cracks in glass - once the crack starts it tends to keep growing. The best option is to prevent the crack from starting in the first place.

    Because of the relatively slow drying rate that you need to achieve for your planks, you will probably get some minor surface checking. There is not much that you can do to prevent it unless you can put the planks in an environment where you can control the RH% for the next 10 weeks. That's probably a long shot...

  15. #15
    Join Date
    Sep 2008
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    To echo some of Scott's comments:

    You want to air-dry green wood s-l-o-w-l-y. The stress cracks happen because of the moisture gradient in the wood between the wet inside and drier surfaces. That's why you don't want to dry the wood inside - indoor relative humidities are almost universally much lower than outdoors, so the outside will dry much more quickly that it would outside (out of the sun, obviously!). This is generally true even in an unheated space.

    One other tip - if you stack wood over a bare concrete floor, even with stickers between the floor and the wood, there's going to be a good deal more humidity under the stack than on the outside, which leads to those moisture gradients and checking. This is true even if the concrete floor looks and feels dry. If you want it inside because of space limitations or code issues, you'd be best served to put down a layer of thick painter's plastic sheeting on the floor, then put your stickers over that, and the lumber stack on the stickers.

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