Primitive Archer
Main Discussion Area => Bows => Topic started by: Badger on June 08, 2018, 05:37:43 pm
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I have always wondered what would happen if I took a piece of osage for example and placed into a hot box that was running at a steady 200 degrees for maybe 1 week.
If that made a difference I would set out to refine the process, maybe lengthen or shorten the time, raise or lower the temp etc. It wouldn't be hard to test the difference it made. I notice a big difference between long seasoned wood ( 5 years or more) and fresh cut wood ( under 1 year). This might be the type of project some of our new bowyers might look into. It could be done easy enough with foot long scraps.
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I have this peace ot osage that I cut last year I want to resaw it for riser lams so I hot boxed it last month for 6-8 hrs every night for about 3 weeks at 135 F I was to afraid to leave it running while at work unattended it hasn't changed weight for about 3 weeks now so I figure its pretty well dry , but Im wondering if shorter peaces season quicker its ruffly 29 '' x 2'' x 2'' I have osage staves hanging on the wall 20-50 % RH inside that some are still reflexing more after 2 1/2 years.
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I am talking specifically about seasoning as opposed to drying. I think the chemical make up of the wood continues to change a bit over extended periods.
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So your saying the higher heat 200 F seasons as opposed to drying ? I guess I didn't understand what you where saying ?
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Seasoning the wood is a different process than drying the wood. Seasoning allows the different chemicals in the wood to stabilize. It usually takes several years.
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Sometimes even dry wood(old osage) can check if subjected to high heat for long periods of time, like a hot summer.
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So, are you thinking that "seasoning" is the evaporation of the volatile portions of the resins. Like pitch takes forever to harden on it's own and some heat speeds that up. If you did short pieces you could make them thin(you would want to anyway so you could bend them) and it wouldn't take as long. What differences would you be looking for?
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Steve, what differences have you noticed between dried and seasoned wood?
Remember that we have kiln dried wood to compare log staves too.
I'm not sure I've seen much of a difference if any.
Jawge
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Jawge, osage is the only well seasoned wood I have worked with. I have had several over the years where someone had something stored and they gave it to me. I haven't worked with enough to say positively but I think it is less prone to taking set and is a bit stiffer. I know some of my older osage bows that have been sitting around will pack on a few pounds over the years.
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All of the evidence seems to point to the resinous compounds in Osage basically curing like a super slow cure epoxy.
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I have two pieces of honey locust that are over 25 years old. The wood is marginal selfbow wood IMO. These two pieces of wood are so hard that I gave up trying to chase a ring on because they are so hard. Seasoned verses dry is a real thing. Doesn't add to the topic but thought I would mention it.
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Interesting thoughts, Steve and PatM.
Worked lots of seasoned woods both whitewoods and osage.
Just-dried woods have been BL which seems to get a bad rap in bowyer communities but which is a pretty darn good bow wood. NH BL is good stuff just-dried or seasoned. But anyway...getting tired.
I don't make enough bows these days (almost 70 y/o) to experimentally determine much of anything so you are smart in handing this one off to some young bowyers.
So to help any possible takers...what criteria would they use to evaluate any differences?
Seems like a difficult question to tackle. Keeping everything the same in 2 different pieces of wood while only varying 1 factor...namely dry vs seasoned may be a tall order. Then a sample of 1 or 2 just is not enough. How many are?
Then there is the problem of preconceived notions influencing results in that you've already said in your intro post you noticed a difference.
But I seem to recall TBB1 having some info tucked in there regarding this issue but they may have had some of the same experimental problems I mentioned.
I seem to have lots of seasoned wood LOL. No need to work the just-dried stuff.
Seems like we bowyers rely a lot on anecdotal evidence and that's ok with me...hard to do much else. Bowyering is an art. I did science all my life and kind of retired that. I'll leave that to you. :)
Anyway, have fun. Going to bed. I'll count staves rather than sheep. :)
Jawge
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I was thinking of this broadhead event coming up and kind of projecting into the future some what ifs. If the broadhead flight competition were to catch on and we have say a couple of hundred bows per year entered states wide at different venues the records would likely creep up to a point they became very difficult to break. When you stop to think that there are a total of 60 records to go after there are lots of opportunities to chase records in your favorite class. But getting back to the seasoning, at some point we will be looking for every edge we can find because the records will be going up pretty quickly. I doubt we will see any new designs but I suspect we will be seeing optimized execution of designs. The quality of staves and wood being used will be a major factor in this.
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But people will be using different types of broadheads. Yes? Dried vs seasoned needs to be the only variable changed.
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Historically, using kiln-dried wood was strongly condemned for either bows or airplanes. But even kilns don't get to 200 degrees.
Then to, making wood more springy or stiffer would not necessarily improve cast, unless less mass was required to get a certain rate of return.
I have read several academic papers on the results of high heat on wood. Don't remember the results except that it seemed there was nothing to be gained for bowyery.
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Jim, I think seasoning does give bows with slightly less mass but I see the biggest gains in less hysteresis. I have no idea if seasoning could be sped up with heat or not but I think it might be worth a try.
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It is a question I think to ponder though.This is assuming all wood of a species is the same before.With no enviornmental influences during it's growing period.
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Would the difference between what you want to do and kiln drying be temperature or time or?
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Could you use a solvent? I've leached resins out of birch bark using alcohol, evaporated it off, and been left with quite a bit of tar. Could the sap, resins, and volitiles be simply removed with acetone or alcohol? And how would that affect the integrity and final product of the wood?
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The process of kiln drying has improved over the years. I made lots of very fine bows from kiln dried lumber. I don't own a chrono but board bows seem to have some giddy-up. Jawge
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Well, at first I thought this was supposed to be in the cooking forum but now I wonder, is it really the volatiles stabilizing or evaporating? They seem like dead weight to me and if they evaporated off, then it could explain why they’re snappier.
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Ryan, I doubt they would account for enough weight to barely be measurable. Osage has latex in it.
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heres my 2 cents,, I was talking to a farmer that used osage for fence,, he said when fresh he can drive a staple in it,, but if it gets dry,, then he cant,, so its getting harder as it dries for sure,, ok at some point in curing it not gonna get harder very fast,, example,, gets alot harder the first 5 years,, then the next 5 years not so much, then after that there is a point of very little change,, like not much difference between a stave 25 years old and 50 years old,, but probably some, and not sure if that difference would translate into a better bow,, but not discounting that it might either,,, (SH)
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When you stop to think about it all wood is dead wood except the cambium layer. The only difference is that after it dries out it starts to season. I don't think it is a matter of forcing out the volatiles as much as it is just let them do their thing and harden up or whatever it is they do over time. Curious if a little added heat might speed that up.
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Badger. Anything I say here is just a guess since most of the staves your talking about have been it cut longer than I've been making bows. Could it be that the wood keeps shrinking?
Bjrogg
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Wow Brad …...Don't think I could have said it better...;)
DBar
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Locals here use osage for posts and fence line.I've fixed many old fence lines here.1 year of seasoning and staples or nails won't go in.Some posts in the ground I'm told for over 80 years.Use posts for structure in ponds for fish too.Locals say they turn to iron in 50 years.
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It's clear that something changes when sap wood becomes heart wood. It seems from peeling off sapwood on Osage that the change takes a couple or three years. But does it keep on slowly changing after the color change????
I know one compound you don't want to go away is lignin. You'd be left with wood pulp.
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Osage outlaw gave me a small stave at Marshall that was split from wood supposedly drying for at least 25 years. I accidentally left it in my vehicle for the next few days where it was 90+ outside and it checked like crazy. I’d be cautious with nice staves and that high heat.
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In my opinion, there should be a noticeable difference between seasoned and not seasoned wood.
I once made a longbow of yew wood, that I cut half a year before. The wood was definitely dry when I built the bow as it didn´t loose weight anymore. The bow had 50 lbs @ 28". I didn´t use the bow for almost two years after that. When I shot it again, it felt stronger and faster then before. I measured 55 lbs @ 28"! That´s a gain in draw weight of 10 percent.
I also read that someone tested arrow spines of dried and seasoned arrow shafts. The spines of the seasond shafts were also about 10 percent higher. That´s about the same number!
Some years ago, I had a discussion with a guitar maker who seasons the woods for twelve years in general. He told me that well seasoned woods don´t respond to changes in humidity as much as shortly seasoned woods.
Longbow makers from the 19th and early 20th century seasoned their woods for about five years. They did so, because well seasoned wood doesn´t crystal as easily, as not well seasoned woods.
Here is my conclusion: Bows from well seasoned woods can be made lighter because they need almost 10 percent less wood for the same draw weight. In addition to that, higher cross sections can be made, because the wood doesn´t crystal as easily. And I do also think that bows from well seasoned woods don´t take as much set during high humidity, because the seasoned wood doesn´t respond so much to changes in weather.
I thought about making bows from short seasoned woods some time ago. From my present standpoint, I will definitely give it some time to season.
Greetings,
lonbow
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I have a couple Osage staves really double staves probably make 4 bows I got from Clint I have them stored in my rafters Where it gets on average 103 F in the summer I coated them with 4 coats of spray shellac & 2 coats of spray poly I take them down every couple of months and see no checks there taking nice reflex , I really dont no if there is a way to speed seasoning other then time I have another sapling stave with bark on thats suposed to be 20'years every time I pick it up the bark is so dry it comes off in chunks I have another thats 25 yrs old that is dark like walnut maybe the color change indicates seasoning ?
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In my opinion there is difference between seasoned and dry staves. A stave can be decades old and still hold too much moisture if they were stored in a humid or moist environment. I've roughed out bows from staves over 20 years old that were stored in my garage. I put them in my hot box for a while and got drying checks that weren't there before.
You can take a fresh cut stave, rough out a bow, and carefully speed dry it. You can get it to a point where it's dry enough to make a bow but I don't think it will perform as good as a stave that is seasoned and dry. I believe that's the combination that makes the best bow wood. I rough out a lot of bows and store them in my house until I'm ready to make a bow from them.
Badger, do you think one long heat session or cycles of heat would be better at speeding up the seasoning of a stave? What if you were able to add pressure to the heat? I'm not so sure it can be done.
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Funny you said that, I was also thinking pressure and heat. No idea how much pressure. Maybe if we understood better exactly what takes place while the wood seasons we would have a better idea how to duplicate it. I think things like lignin and latexes in the wood tend to harden up and bond with attaching fibers. maybe the volatiles are leaving very slowly, if that's the case maybe heat and vacuum.
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They sell vacuum bags and hand pump for laminating or veneere at some wood working stores or net you could just throw the stave & bag in the hot box it's designed for the heat ! Or they have the storage bags you can hook to your vacuum at the big box depends how much of a vacuum you want & I don't know how high of heat those would take !
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Vacuum lowers the boiling point of water. I think at -29 the boiling point is 72° but I may be mistaken. I know that vacuum kilns exist but don’t know much about them. At work, we have vacuum loading pumps that deadhead @ -40. I’ve thought about making a simple foot long vessel out of 4” threaded iron pipe with a cap on one end and bell reducer and ball valve on the other. Idea is to place in the pipe a fresh off cut piece of a bowstave split and some desiccate and pull all the vacuum on it I can. I would like to see how quickly it dries this way ( I’m thinking very ) and if there’s any adverse effects as seen in other drying methods. With a small test sample such as this, would there be a way to test if the wood is changing as seasoned wood does?
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Every time this topic comes around I mention the process bamboo flyrod makers often use to make their rod blanks more stable compression resistant and stiffer.
Pretty sure the answer is there. Originally they even used the same essential compound that is found in heartwood.
All of the points are covered. Types of resinous compounds, heat, pressure, cure time etc.
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Osage outlaw gave me a small stave at Marshall that was split from wood supposedly drying for at least 25 years. I accidentally left it in my vehicle for the next few days where it was 90+ outside and it checked like crazy. I’d be cautious with nice staves and that high heat.
Exactly my thoughts doc. A fresh stave left in 200 degree heat would be a complete mess in a day or so. I got a log from Clint several years ago. I split out 8-10 staves and put them in my garage, 80-90 degrees in the summer. In a few days they were all firewood. Side checks and back checks throughout. The best way to cure/dry osage IMO is to leave it somewhere dark and around 50-60% humidity for a few years. Then rough it out and sit it on an AC/Heat register for a few weeks do get it just a bit more dried out. I love my results.
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Slow drying and aging is great. The fast-dry concept was born of the desire to hurry up and start making that first bow.
OTOH, I have several bows that lost draw weight over a few months without gaining string follow. No idea why.
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As a side note,I'm starting to think that elm staves stored in my shed over winter and subjected to up to-44f seem to be better bow wood than others that I stored inside in the past!kinda like a freezer burnt steak effect!
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I agree with most of the above, I haven't seen any substitute yet for simply aging the wood. I would be nice if we could find a way but I imagine we would have to know what was happening during the aging process before we could figure out how to replicate it.
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Those Okies would figure out how to make a six ft long microwave. Now that's thinking out side the box.
Arvin
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Those Okies would figure out how to make a six ft long microwave. Now that's out side the box.
Arvin
(lol) (lol)
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Those Okies would figure out how to make a six ft long microwave. Now that's out side the box.
Arvin
(lol) (lol)
Do it all the time works great!
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Vinemaple are you growing any extra ears or such? I have heard of cutting a hole in each side. Is that what y'all do. And will it dry or season a stave? Arvin
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I haven't seen any substitute yet for simply aging the wood. I would be nice if we could find a way but I imagine we would have to know what was happening during the aging process before we could figure out how to replicate it.
Despite how much I value the opinions of so many experienced bowyers on this site and over the years, I am still more prone to dismiss the effects of "seasoning" vs drying, for MOST species, in MOST situations. My own experience mirrors the line from Torges' books..."Cast comes from dry wood properly tillered" and I still think the dogma that bow wood MUST be seasoned slowly for years to even MAKE a bow is nonsense.
However, I'll add some interesting links about a recently developed industrial process that hardens and strengthens commonly weak woods like poplar a RIDICULOUS amount. So chemically changing wood must be possible, and thus, I must admit that there COULD be SOME natural process that does the same.
My first thought is that this "seasoning" effect may only exist in some species. EVERYONE here has more osage experience than I do, but I have not noted improvement in elm, ash, maple, etc. that I let sit around for years before working, even in good conditions. Quite the opposite, in fact. So maybe osage, yew, and some other very resinous tropicals are affected? BL heartwood?
The problem is we would really have to take a large sample of sister billets, dry them to exactly the same MC, make exactly the same bows, and then leave one to season for however many years, then shoot it again. Then we have to measure set, cast, cast per mass, etc...
Now, I must admit that it never occurred to me there might be substances within wood besides water that remain liquid, pitchy, or latex-like that may harden over time. Makes the most sense to me that if this is happening, those may be the culprit.
Almost ALL chemical reactions are accelerated or catalyzed by heat, but perhaps the "magic bullet" of belly tempering does this as well or better than long-term kilning would. I know for a fact that over-drying wood will quickly take back any ground you may have gained.
NOW, here is the funny part to me. These articles discuss a process that results in extrordinary strength and hardness of wood by compressing it, BUT!!!!!! here they chemically REMOVE some of the polymers, including some, but not all of the lignin.
https://www.smithsonianmag.com/smart-news/chemical-bath-and-strong-squeeze-makes-super-dense-and-strong-wood-180968117/
https://www.nature.com/articles/d41586-018-01600-6
https://www.sciencealert.com/new-super-wood-stronger-than-steel
https://www.popularmechanics.com/science/environment/a16758876/chemical-treated-super-wood-steel/
I can't find an article right now, but I read something else about a similar chemical process, but with less compaction that still tripled the strength of common woods.
And, finally, this product is so volatile (dries so fast) that it doesn't penetrate wood deeply, and I haven't figured a way out yet to let wood just bathe in it. But, I will, and I'll use it on just the bellies of bamboo and some white woods.
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Springbuck intereasting. I had a guy give me some compressed oak that was used for loading heavy pipes on trailers. Was compressed to like 20000 psi. Not sure of the process but it made crappy bow wood. No elasticity. Arvin
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Springbuck, I would say 95% of the bows I have made were made from wood that was dried fairly fast. I have only made a handful of bows in my life from well seasoned wood. I have to say there is not a big difference but enough of a difference for an experienced bowyer to feel it.
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Springbuck, I think you and I have the same thought process on this. I believe that the woods that benefit from seasoning are the resinous pitchy woods. Whitewoods, don’t think it makes a hill of beans.
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Ok guys I got my hands on a good stave that was cut some 25-30 years ago just yesterday and if I do my job we will see. Steve I also have only worked On a couple of seasoned staves .this will be the most seasoned so far. What I have noticed on them is they are hard as a rock on the out side when you start to peel them. Wish me luck. Arvin
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It is my understanding that uneven drying (shrinkage) is what causes detrimental stresses, so if you were to make sure that the stave was completely dry through and through before you raised the temp?
or keep some humidity in the high temp box so that the MC stays at equilibrium? ie some sort of steam process?
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I have definitely seen benefit's in seasoned wood (even white woods like oak and yellow woods) but am curious as to why and how a large piece of wood such as a stave would get much harder and denser while a selfbow made out of unseasoned wood might see little to no change over the years. The wood that has been turned into a bow would technically still be seasoning.
I made a bow out of Sumac about 1 year ago that was seasoned (or dried) within 3 month's of harvesting it and I checked the weight on it a week ago and it's the same draw weight as it was when I built it 3 month's after harvesting.
And while darker wood's such as Osage will have more compounds and oil's in them naturally, even white wood's and yellow wood's have compound's in them that should harden over time as well since that is a part of what gives them durability, weather resistance, and so on.
Perhaps the wood has to season by letting it dry out extremely slowly without ever reducing it down until year's have gone by?
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Every six months I turn my staves to even the sap and moisture in the wood while the hot and the cold temper the wood over a course of at least six years for me to consider my yew fully Seasoned.