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Thread: Air Drying Walnut

  1. #1
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    Air Drying Walnut

    I read Scott's Sticky, but have a few questions and somewhat specific to Walnut. My source for KD walnut dried up during Covid and is no longer transporting or selling dried lumber. He was probably a few years away from retirement and the pandemic hastened his departure. This has me now considering two smaller mills that are 40-50 miles away and buying green walnut to air dry. Looks like 3,000-4,000 bdft of ungraded walnut is in the $1.90-2 a bdft range. I spoke at length with the one sawyer and he said most of the walnut logs he buys and saws produce select and better boards with some 1com and some FAS mixed in. It sucks because im used to buying KD walnut for $3-4 a bdft for select and better, but those days are done. Here are my questions:

    Do i have to worry too much about bugs and walnut heartwood? Ive noticed PPB in walnut sapwood before, but i dont know that ive ever seen heartwood affected by the bugs. Ive been under the impression the heartwood is poisonous to most insects? This may be my own myth, which is why i want to ask.

    On drying rates, does lumber dry much during the winter, or not at all? Scott's sticky dispels the 1"=1 year myth, but does anyone have experience air drying 4/4, 5/4, and 8/4 walnut in the northeast? Im not necessarily in a rush to dry this wood as fast as possible, but it will be convenient if its down to 15% MC come next spring/summer so i can move it inside my shop and get it out of the elements. It also factors into the decision to do this in the first place. If the 4/4-5/4 can be used next summer and the 8/4 shortly thereafter then its worth the time and effort. If i will be waiting 3 years for the 8/4 to mature, then this probably isnt for me.

    Generally is this a worthwhile experience, or do a few of you have horror stories? I like the price and ive noticed air dried material has slightly better color and workability, but those characteristics go out the window if bugs are unavoidable and my wife has to look at a stack of lumber in our driveway for 3 years.

  2. #2
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    Quote Originally Posted by Patrick Kane View Post
    I read Scott's Sticky, but have a few questions and somewhat specific to Walnut. My source for KD walnut dried up during Covid and is no longer transporting or selling dried lumber. He was probably a few years away from retirement and the pandemic hastened his departure. This has me now considering two smaller mills that are 40-50 miles away and buying green walnut to air dry. Looks like 3,000-4,000 bdft of ungraded walnut is in the $1.90-2 a bdft range. I spoke at length with the one sawyer and he said most of the walnut logs he buys and saws produce select and better boards with some 1com and some FAS mixed in. It sucks because im used to buying KD walnut for $3-4 a bdft for select and better, but those days are done. Here are my questions:

    Do i have to worry too much about bugs and walnut heartwood? Ive noticed PPB in walnut sapwood before, but i dont know that ive ever seen heartwood affected by the bugs. Ive been under the impression the heartwood is poisonous to most insects? This may be my own myth, which is why i want to ask.

    Black Walnut heartwood is toxic to many pests, but I have seen one instance of fresh termites in it. In general, black walnut air dries very easily, and the heartwood is not susceptible to most pests.

    On drying rates, does lumber dry much during the winter, or not at all? Scott's sticky dispels the 1"=1 year myth, but does anyone have experience air drying 4/4, 5/4, and 8/4 walnut in the northeast? Im not necessarily in a rush to dry this wood as fast as possible, but it will be convenient if its down to 15% MC come next spring/summer so i can move it inside my shop and get it out of the elements. It also factors into the decision to do this in the first place. If the 4/4-5/4 can be used next summer and the 8/4 shortly thereafter then its worth the time and effort. If i will be waiting 3 years for the 8/4 to mature, then this probably isnt for me.

    Lumber drying rates slow down significantly below 70 degrees, and especially below 50 degrees; however it does still dry somewhat. In general, air drying that is started in the fall and winter months will result in higher quality lumber - especially less surface checking. I much prefer to start air drying thick slabs in the cooler months. Your 8/4 BW should be fully air dried by the end of next summer; and the 4/4 at the start of summer. Sometimes BW though can plateau, and stop drying for a while. This is more related to the individual log though.

    Generally is this a worthwhile experience, or do a few of you have horror stories? I like the price and ive noticed air dried material has slightly better color and workability, but those characteristics go out the window if bugs are unavoidable and my wife has to look at a stack of lumber in our driveway for 3 years.
    My advice is go for it! It's best if you can air dry under a shelter - such as a carport - that has unrestricted air flow. The prices that you referenced are excellent considering the current market. If you're interested in a mix of live edge and straight edge lumber, I would request that your sawyer edge any BW boards that have a wide sapwood band along the edge, and only select logs with narrower sapwood bands for the live edge lumber. Fast growth BW is notorious for splitting severely from the ends - even with end sealer. The reason why is that although it dries at the same percentage, BW sapwood dries much faster than heartwood and it shrinks as it dries. Thus there can be a tension band running down the perimeter of the live edge slabs that tends to rip them apart from the ends. Boards with narrow sapwood bands are not as problematic.

    IF at all possible, buy your BW lumber in boule form. That will allow you to easily bookmatch a lot of the boards in your projects.

  3. #3
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    I live in WNY. I have not had problems with bugs in the heartwood of walnut, or most other woods for that matter. Drying is very much dependent upon when the wood was cut. If I cut 4/4 lumber in March it will be AD in 4 months, but if I cut it in October it won't be AD for at least 7 months. Winter drying is only 1%/month in my solar kiln so racks outside aren't going to be any more. 5/4 lumber is pretty similar to 4/4, maybe another month or two, but 8/4 takes more like 18 months to get to AD

    As impatient as I am I've learned not to try to rush things when air drying wood. I lost quite a lot of white oak from direct sun exposure once, so now I make sure my wood stacks are under tree cover and only get filtered sunlight. If you don't have a way to keep your stacks of wood out of direct sunlight then I would drape landscape fabric around them to shield the wood. Walnut is pretty tolerant but an added couple of months is far better than checking.

    John

  4. #4
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    Great, that is all pretty encouraging stuff. Especially on the bug front. I think this will be a go, im just waiting on a lumber trucker with a boom lift to give me a quote. The sawyer works with this guy a lot and guesstimated $300-350 which seems super cheap.

    Here are my stacking/stickering choices.

    Upper portion of my driveway that is mostly out of the way of vehicular traffic. Pros for this position is its asphalt on a concrete subgrade, which means weight isnt much of an issue. Should be relatively flat to begin with and easily shimmable for the base course. Cons are its in the driveway, so a bit of an eyesore, but it also receives about 6-8 hours of sunlight. I have scrap plywood and a tarp to keep the precipitation mostly off the stack, but the side and one end will get blasted with sunlight.

    Another choice is inside my recently completed shed. its 8' wide and 10' deep with a 16' ceiling. Pros are its under roof and completely out of the way. Cons are i didnt build the floor to hold 9,000lbs of lumber. The floor joists are PT 2x6s 12" on center connected to 6x6 sills via joist hangers. The sills are on buried deck blocks sitting on a deposit of sandstone. I have deck blocks every 3-4' on the perimeter of the sills. The floor joists are quite close to the ground. So much so that i am sure the floor joist would contact and transfer load to the ground before breaking. Still, i imagined putting 2,000lbs on the floor of the shed and not 5x that. I currently do not have front doors on the structure, and could leave the 4' by 7' door freely open for air exchange. I havent closed in the openings between the roof and the purlins either. I left this open for the timber frame to breathe and continue to dry until the spring. This might be overly cautious, but i didnt want the hemlock(was alive and standing in June) to mildew by sealing up the shed too soon. It wont see the air exchange that the driveway stack would, but it would be completely under roof.

    Scott, i tend to infrequently buy lumber in larger lots for this reason--well, and prices and delivery convenience. At wholesale lumber yards, if you buy 'whole packs' you typically end up with boards from the same/similar trees. Its my understanding that Boules are live edge material, is that right? Or does a boule just mean the tree is restacked in the same orientation of the original log, but not necessarily live edge? I would prefer not to have bark on the boards for the insect reasons. I have a slider, so i can straight line the live edge off, but its more convenient to start with square stock.

    One final question beyond 'where to stack the stuff' is how do folks typically allocate the cuts? I used to use a ton of 8/4 almost exclusively to make counters, islands, etc. Im doing that less and less these days, and originally considered splitting the order into 1500-2000 bdft for 8/4 and the remaining 1,000 split between 4/4 and 5/4. Im now thinking more of the future and cutting into that latter category for maybe 200-250 feet of 12/4-16/4. I know this is really thick material, but things like a maloof rocker's crest rail require short portions of 12/4. What originally turned me away from these thicker cuts is the dry time. If 8/4 could be ready by the end of next summer, it makes me think about stretching for the 12/4 which might be ready in a year and a half to 2 years.

  5. #5
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    Patrick, you will have the least degrade and fastest turnaround time if you air dry under an open sided shelter, such as a carport.

    Drying indoors - such as in a closed shed - will result in an extended drying time, but the wood quality will be high.

    One concern about drying adjacent to a driveway is for mud / dirt / moisture to be splashed up on the lumber.

    I like your suggested mix of 12/4, 8/4, 5/4 and 4/4.

  6. #6
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    Sent the sawyer his $3,000 deposit earlier this week, and now i eagerly wait a few weeks to move 12,000lbs+ of lumber by hand. Im very interested in how this turns out. One, how quickly the lumber dries and is usable. Two, how well-tempered and true the lumber dries. Three, how awful moving that much in a day or two will be. Ive had my share of moving a few thousand boardfeet in one day, but never green material. If this goes well, i see myself doing this every or every other Fall, selling off the 1com the following year for a small profit, and keeping the select and better/FAS for a bargain of an investment.

  7. #7
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    Quote Originally Posted by Patrick Kane View Post
    ... move 12,000lbs+ of lumber by hand...
    Wet lumber is very heavy, especially wide 12/4 boards. A tractor with forks on the front saves a HUGE amount of manual effort. I slide boards onto the forks from the mill then set the stack out of the way on 4x4s until stickering time. If you have a tractor with a quick connect for the bucket you can switch between the bucket and forks quickly.

    JKJ

  8. #8
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    If you are making crest rails etc from it, the 12/4 and 16/4 will probably end up rough cut while still only half dried then left to acclimate in your shop.

    I'd go with driveway drying. Put it up on fairly tall blocks (12" min) to keep it out of rain splatter and to give it good circulation. Maybe a layer of tar paper or something in there will discourage bugs. You may want to discourage mice and chipmunks as well.

    Definitely keep direct sunlight off it and limit air circulation. Landscape fabric might be enough but double it on the end and side exposed to direct sunlight.

    Make up plenty of sticker stock ahead of time. Someone here can advise about sticker stain.

  9. #9
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    A small update to my experience so far. One, stacking over 3,000 bdft of wet lumber sucks, but thank the almighty that this guy was able to get his log truck up into my driveway. Afterwards, he used the gantry crane onboard to offload the load within 20’ of where I planned on stacking it. Moving that much wet wood and stacking it 6-7’ tall still was a lot of work, but atleast I didn’t have to carry it 100’. I have three leveled stacks about 40-48” wide and 6’+ tall. The 12/4 is on the bottom of the stacks with 8/4 on top of that and some stacks have the 5/4 on top of that. I keep it tarped when rain is in the forecast and roll up the tarp when it’s dry for a few days in a row.

    Here is my question. I finally got a moisture meter. It’s a used ligno SD pinless scanner at a fantastic price. Here are my results thus far. The 5/4 at 3/4” depth is about 15.5%. It’s closer to 12-13% at 1/4” depth. The 8/4 is a little higher around 16.4% at 3/4” depth. Finally, the 12/4 is 18%. As an experiment, I moved a few pieces into my basement to track alongside the stuff stacked outside. Surprisingly, the values are very very close. The kiln dried walnut that has been in my shop for years is around 9-10%. It seems like this green wood is drying pretty quickly. Can I expect the 5/4 to dry down to 10-12% over the next 2-3 months? At what point do I need to bring it inside to finish drying? For about 45 days of drying, this seems like it’s going very well.

  10. #10
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    If it's less than 20% MC it was either milled quite some time ago or the logs were really old. Green walnut has a really high MC. If the lumber looks good then hopefully it is. It's sure not going to take nearly as long to dry.

    John

  11. #11
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    That’s why I’m confused, because this was soaking wet when I stacked it. Heavy as heck and dripping wet. And it’s not like it sat in the rain prior to stacking it.

    I mean, I guess I’ll take it! Other than some very minor checking on the ends, it is drying very flat and well.

  12. #12
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    We had a black walnut tree cut down about two weeks ago, a week later the sawyer made the two straight trunk parts into 20 boards, 6/4 thick, ~12" wide and nine feet long, and one that starts at 6/4 and ends at 5" thick (maybe due to a dull blade). Most of the boards are very nice dark black walnut, others are interesting mixed heartwood and sapwood, and three are mostly sapwood.

    I stacked and stickered them in the shop, where the mini-split controls temperature. Stacking them outside or in the shed is not an option here. Current shop temp 68 and humidity about 55%.

    My Wagner Moisture meter maxes out at 30%. The wood is very heavy and my guess is it's way wetter than 30%.

    One more thing - if the boards had been cut thicker than 6/4, they would be a PITA to move and stack by hand. I had to call my neighbor to help stack the way-too-heavy tapered board.

    We'll see how this turns out in a year or so.

    Jim

  13. #13
    Although the tapered piece could be a mistake, it may also be a remnant. Does it contain the pith (the heart of the log)?. There are many ways to saw a log and, from you description, it sounds as though it may have been grade sawn. When the sawyer levels the top of the log for the first cut, he is sawing parallel to the bark, which gives the straightest grain pattern, the first board or two will mostly be sapwood. He may rotate the log either 90 degrees and square the edge, or 180 degrees. At that point he would use the toe boards to level the top surface of the log again, creating lumber with the straightest grain pattern. After sawing down through the log, he would be left with a tapered piece of wood that contains the pith (lower quality wood). If it was the butt log and had significant taper (potentially about 3.5" larger at the bottom than at the top), that would explain that degree of taper in the final piece on the mill. Had he made another pass he would have split the pith making an unusable board (or one less than your specification).

    I explain this to my clients before we start milling, often they will make use of that tapered piece by cutting it into turning blocks, or other uses. Communication is the key, you could ask the sawyer why it was done that way. It sounds as though he gave everything that your logs yielded, perhaps some of it should have ended up on the scrap pile. It has been my experience that a blade that dives is usually related to hitting a nail or a rock and the dive is more drastic, not a tapered path. On my mill, I don't think my blades could dive 3.5" without smoking and breaking the band. I watch my cuts and any problem is normally caught within a foot or so.

  14. #14
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    Quote Originally Posted by Jim Falsetti View Post
    We had a black walnut tree cut down about two weeks ago, a week later the sawyer made the two straight trunk parts into 20 boards, 6/4 thick, ~12" wide and nine feet long, and one that starts at 6/4 and ends at 5" thick (maybe due to a dull blade). Most of the boards are very nice dark black walnut, others are interesting mixed heartwood and sapwood, and three are mostly sapwood.

    I stacked and stickered them in the shop, where the mini-split controls temperature. Stacking them outside or in the shed is not an option here. Current shop temp 68 and humidity about 55%.

    My Wagner Moisture meter maxes out at 30%. The wood is very heavy and my guess is it's way wetter than 30%.

    One more thing - if the boards had been cut thicker than 6/4, they would be a PITA to move and stack by hand. I had to call my neighbor to help stack the way-too-heavy tapered board.

    We'll see how this turns out in a year or so.

    Jim

    OK, I looked it up. Green black walnut has a moisture content of 90% for the heartwood. Freshly cut logs will ooze water out the ends if you stand them up. Maybe your tree had slightly lower moisture content now that the sap has run down into the roots, but it's still screaming high. That's a preface to say that 55% RH is far too low for safely drying it. You should cut a physical sample from one of your boards and determine the MC using the oven dry method. You can look up drying schedules for wood at the FPL website or at EBAC for their dehumidification kilns. Both will tell you that the RH needs to be above 80% until the MC gets down to 40%. Most defects are initiated in the first 1/3 of the drying cycle, so that's right now or your lumber.

    Should it be necessary, you can slow down the drying by putting a plastic tent around your wood stack, using a fan to circulate air, and adding a dehumidifier to control the RH. A heater can be added, too, to raise the ambient temperature to speed up the process without risk of damage because you are controlling the RH. I used to dry wood in my basement with a dehumidification kiln that ran at 110F. In the end, I found partial air drying outdoors was far easier than trying to dry green lumber indoors. Once the MC gets down below 40%, and preferably below 30%, it's far easier to control the drying process indoors without risk of creating defects.

    John

  15. #15
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    Tom, thanks for taking the time to comment.

    The sawyer asked if I wanted boards that were square on the sides, and described rotating the log to do that. I believe what he was doing was maximizing the yield of straight edged boards. As he did each side, there were "cover" pieces, sapwood and bark, and some odd shaped smaller ones, that my neighbor took for either firewood or to make a rustic bench. My wife wants a potting bench, and I was thinking the sapwood might work for that purpose.

    The tapered piece is also mostly sapwood. I'm not sure what part of the trunk that was, but definitely not the pith. I thought if it dries ok, it could be used for legs.

    At one point, we had a very wavy board. He stopped and we looked for nails or rocks but there were none. He said the blade must be dull, and he changed it, and the boards were OK after that.

    Jim

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