Best bet?

[Kegan]

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?

[Justin Snyder]

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

[sailordad]

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 

no seriously i remember reading that on here.

                                                             peace,
                                                                   tim

[The Burnt Hill Archer]

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

Phil

[GraemeK]

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

[radius]

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

[The Burnt Hill Archer]

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! this is the part of bowyery where my mind kinda glazes over...

[GraemeK]

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

[GraemeK]

Hi Phil

Sorry about that -- just think about it like Myth Busters where they warn you about science content ----- Graeme

[sailordad]

  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

[Pat B]

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

[Badger]

     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

[JackCrafty]

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

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...)

[GraemeK]

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

[Pappy]

Salt water  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. 
   Pappy