Primitive Archer
Main Discussion Area => Bows => Topic started by: Kegan on July 14, 2008, 07:05:51 pm
-
Though I've managed several nice quick dried staves, and have seen alot of skilled bowyers make excellent weapons in wood quick-cured in less than a month, I still have to ask- is it the best bet to just let the wood sit in a safe, dry, warm spot for several months? I'm here refering to drying for moisture content, not safety from bugs/checking/other problems.
What do you guys think?
-
I have heard some guys say that there is a difference between dry and cured staves. I say if you have time let it cure a little. Justin
-
i remember reading on here just a short while back in one of the threads about something or other,you now they get off track once in awhile.
but some of the folks were saying that they found that the longer it cured the better it seemed to turn out. maybe it was on here, sometimes things happen so fast its all a blur for one reason or another my mind tends to wonder ??? :P
no seriously i remember reading that on here.
peace,
tim
-
it kinda makes sence i guess, letting it cure a while. like Justin said, its not only dry, but the wood has a chance to stabalize and adjust to its new mc. maybe not, but it makes sence to me ;D
Phil
-
There are other processes than losing water going on in the wood structure as it ages.
These mainly consist of the volatile aromatic compounds undergoing polymerisation
and binding to the lignin which in many cases increases the strength. Since these changes are
much slower than the loss of water it follows that aging is of value, the unknown is how much value.
Some wood gains much more strength than others over time and in most cases the gains are statistically small.
Graeme
-
Okay Graeme, good stuff...but????
Can you speed up the curing process? I don't mean just helping water out of the wood, i mean actually accelerate the chemical processes you're talking about.
Or is time the only solution?
Scott
-
There are other processes than losing water going on in the wood structure as it ages.
These mainly consist of the volatile aromatic compounds undergoing polymerisation
and binding to the lignin which in many cases increases the strength. Since these changes are
much slower than the loss of water it follows that aging is of value, the unknown is how much value.
Some wood gains much more strength than others over time and in most cases the gains are statistically small.
Graeme
yeah, thats what i said, only smarter! :D this is the part of bowyery where my mind kinda glazes over...
-
Hi Scott
All these type of organic polymer changes are affected by temperature -- think the changes in red wine which you normally want to slow down so you store the wine at around 12 deg C which gives slow changes.
If you want to speed the changes the higher the temp the better but there are practical limits to the max temp you can hold the wood at for extended periods without causing degradation. I would suggest a max temp of about 35 deg C for extended periods should be ok but it is hard to estimate how much this will speed the process and the only way to develop an idea about the time necessary would be to do repeated physical testing which would allow you to develop a regime that works for most timber.
My personal experience suggests a couple of months at 35 degC gives the sort of changes you would get in a year at ambient temps of 15 to 20 deg C ( remembering that the average temp even in warm places is lower than you think when you consider overnight temps and summer winter differences ) .
You do need to be absolutely sure the timber you do this to is evenly dry before you start and that you raise the temp to the high figure over a few days or you may cause splitting. Also in some very resinous timbers the higher temp may cause splitting due to loss of aromatics even if it is very dry to start with.
Obviously after a couple of months at elevated temps you would have to allow the timber to regain a safe working MC before you tried to make a bow from it.
Graem
-
Hi Phil
Sorry about that -- just think about it like Myth Busters where they warn you about science content ----- Graeme
-
??? ??? o.k this is getting way to complicated for me today.
heck i'm still trying to figure out what the heck 35celsius is in real temp like Fahrenheit ??? ??? ??? :P :-\
-
I'm sure that today we can force cure wood...if you have the cash and connections. I know that dry wood isn't necessarily cured cured. I believe that wood cures over a long period of time. Most of the archery old timers preferred their osage and yew be cured at least 10 years.
I am almost finished with an osage static recurve from wood that was harvested May 8, 2008. This wood is dry but I can imagine it increasing in weight or experiencing tiller change over the next year or so. I haven't done any force drying at all. I did reduce the original stave to 3 separate staves and the one this bow came from was the belly split. It was cut to rough shape about a month after harvest and the back was sealed with shellac. The ends already had a heavy coat of wax sealing them. As you can see a good bow can be made in a relatively short time after the wood is harvested. I prefer working with wood that is at least a few years old and I have a few staves that I collected almost 10 years ago.
It seems that heat treating bow bellies is actually "quick curing" the belly wood; forcing the polymerization of the volatile oils and lignins which causes the increase in compression strength of the belly wood. Pat
-
This would be a very good subject for a long term study and report. Maybe as long as 10 years. Not sure how you would want them sealed for a test like this. probably better to seal them up pretty good so that the aromatics remained in the wood longer and would have more time to react with the other chemicals in the wood. Maybe take several samples from various popular species of bow woods and quick air dry a sample from each after it had been cut to a specific measurement and tested in compression, deflection and tension. Then every following year retest the same sample looking for changes, or just slice new samples off and reseal the stave after each sample is taken for testing. We could let the engineers figure that out but it might settle a long standing debate. Steve
-
Hey guys....good topic but this wheel has already been invented. There are extensive studies concerning kiln drying versus air drying (for the lumber industry) and extensive studies concerning the drying/curing/decaying of wood after being sealed, chemically treated, heat treated, and you name it (for the construction industry). You can look up publications written by the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, for starters.
Here's one of my favorite publications:
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf (http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch04.pdf)
Looking at the list of references at the end will give you some idea of how extensively this subject has been researched.
What do I think personally about fast or slow drying? Slow drying is boring. (and so is reading tech manuals...) ;D ;)
-
Hi All
It is true that a great deal of testing has been done and that extensive test results are available which may be useful but the testing has invariably been done with a view to material suitability for the building and furniture making so how this relates timber for bow making is a little uncertain since the requirements are fairly unique.
I think the thing to keep in mind is that if the bow stave has good physical properties for bow making when dried but not aged it will most likely only improve with age but if a stave has unsuitable physical properties when dried but not aged there is little chance that it will improve enough to be useful.
Graeme
-
Salt water ;) ;D ;D ;D sorry just had to say that,all jokes aside I believe it is better to let them cure
for at least a couple of years if possible,especially heart wood,white wood doesn't seem to make as much difference ,I rough out a lot of bows when I get in the mood and just put them up till a
later date and it seems that the ones I forget about and find them a year or 2 later make a better
bows,they seem to stabilize faster when tillering and hold reflex better and take less set.I have
several I plan on building that have been seasoning for several years.10 year test Badger,I don't know,maybe some of these young lads could do that. ;) ;D
Pappy
-
The other thread which talks a bit about dry wood/ cured wood is King Ron's Osage Bow....but this one has now eclipsed that one.
As for you guys who can't read "commonwealth" temperature, well, that's funny...35 degrees is just damn hot!
-
see i still dont know what 35c is,too me its not hot till it hits triple digits and i'm from mn,we know what cold is,hot thats the other 2 weeks of the year ;D
-
It seems to me, that long term curing does seem to have an affect. I've managed to make white wood bows in about a week. However, they were only so-so shooters, and followed the string slightly more than I would have wanted on average- even though they were at an acceptable MC. I have also made bows from other bows, or roughed out staves, that have been sitting around from six to twelve months, or more. These seemed to work better (the wood responded to the tools in a better manner) and stabilize (especially during tillering) more quickly- like Pappy said. Up until now, I just thought it was me though :P.
However, the variation between woods seems quite dramatic. Red oak seems to have reached this "stage" much more quickly than hickory or white oak- red oak reached it in about six months or so, where as hickory can take uo to and over a year to reach it. It also seems to be affected by the size of the stave, and the size of tree that it came from (smaller trees seem to reach it more quickly).
I've got several sister staves, two of which are being "quick cured" in slightly over a month or two, the rest will be set aside for much longer. I'll see if there is any big difference. I'd also like to check how "Indian" bows (small trees roughed out quickly into whitewood bows) age.
-
I don't know about Red Oak but Hickory take a long while to season,you can get it dry pretty
quick by roughing it into a bow and putting it up,but it still ant seasoned.It will make a pretty
good bow quick dried but I think It will make a better one if you can wait a year or 2.That
is why I keep so many roughed out.I will date them ,when they were cut and when they were roughed out,steamed and straighted and reflexed and then just put them up in a cool dry place.
Some don't have that luxury but if you can I think it is better. :)
Pappy
-
Honestly: I don’t know.
One school of thought is that dry wood is dry wood, whether it takes one month or 5 years.
Another school of thought is that drying wood is one part of the seasoning process , and something else happens at the cellular level if you give it enough time. What that "something" is has not been scientifically investigated to my knowledge (I'll have to research hat further..) Could be hokum, could be fact. There's an established tradition of curing wood for long periods of time. If it didn’t serve some purpose, then it wouldn’t have been done.
Unanswered questions.
By default, I tend to season my wood for years at a stretch. I just take my time getting to the good stuff. I have some 10 year old yew, osage, and mulberry waiting to be worked on. I also have some fresh mulberry that'll sit around for a few years. On a side note, I've quick dried by reducing staves to bow dimensions and letting them sit to a clamped 4X6 in 50% RH….the resulting bows seemed to perform just fine.
I've done both with good results.
-
A good argument for long term curing would be the Tulip Poplar(Lariodendron tulipifera [sp?]) that was used in some of the older barns around here. Poplar is a relatively soft wood. After 100 years or so you would have a hard time driving a nail into or pulling a nail out of this wood. Years of curing turn this and other woods to near stone consistancy.
In Dean Torges book, "Hunting the Osage Bow" Dean talks about fast curing green wood somewhat in the steam chamber. Even though the humidity is very high in his steam chamber it still isn't enough to prevent some of the woods moisture to be forced out. Dean did have the back and ends sealed with shellac, which is not affected by the steam, to prevent and drying checks. His staves were near bow size and clamped to a caul so the end result was some added reflex along with dryer wood...but they still aren't cured! IMO Pat
-
Growing up in New England I saw a lot of old wood, old furniture, and old structures. It's true that wood changes over time but I have seen wood that gets harder over time and wood that gets softer over time. Most of the changes occur on the surface of the wood, with the innermost wood hardly changing at all.
There was an article recently about why old violins sound better than new ones. It turns out that scientists using CAT scan technology discovered that the older wood has less variation in density between growth rings than the newer wood. They concluded that the older violins were made from better trees. That's it!
"Curing" might make a bow perform better but I think the effect is only skin deep, so to speak. For the most part, older wood is more brittle and unstable that newer wood. The biggest difference is probably in the quality of the stave, not in the age of the stave....we tend to save our best staves for that "special" time when we think we have enough experience to make that perfect bow we all dream about. ;D
-
I built A Osage naturally reflexed bow it dried for 3 month's it came in at 60# every year it would gain 3# to 5# for 3yrs it did this. After 3yrs of retillering down to 60#It was Finlay stable.. Much snappier than it was to start with..But i was happy with it to start with. So my thoughts are yes fast dried wood builds a good bow!! but cured is better. Just a matter of the time you want to spend waiting..I myself well I don't have the Patience.. ;D
P.S
It also gained a full 1" of reflex over the 3yrs.
Dave
-
I have noticed with hardwood shoot arrows(Art Butner brought this to my attention) they increase in spine weight over a couple of years. That is one reason I cut shoots each year and bundle them and store them. I make my shoot arrows from last years or the year before shoots. The wood is more stable and the spine doesn't change. Pat