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| Author: | RobLak [ Fri Apr 13, 2007 1:37 pm ] |
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OK, i just watched the Volbrecht video that was posted in another thread and i have a question. This guy boiled his sides for 8 minutes on the stove. Now, i had seen a video of the Taylor process on their automated machines and Bob Taylor made a point that i thought was very thoughtful. He said, (something like) "we spend a lot of time drying out our wood so it reaches a maximum stability, for that reason we do not use any water in the bending process." Now i realize almost everyone that has posted here has admitted to wetting, soaking or spritzing water on their sides before bending, so i have two questions. First, does the water really help at all? It must or you wouldn't do it. Secondly, if you can boil the sides, does that mean the whole mystique about drying the wood 37 years is bogus? Thanks, and have fun arguing! (I mean discussing!) Rob |
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| Author: | JohnAbercrombie [ Fri Apr 13, 2007 2:06 pm ] |
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[QUOTE=RobLak] First, does the water really help at all? It must or you wouldn't do it. Secondly, if you can boil the sides, does that mean the whole mystique about drying the wood 37 years is bogus? Rob [/QUOTE] Rob- Water definitely helps in bending wood- boatbuilders routinely bend wood much thicker than guitar sides (not to the same curves, though) after steaming. Don't forget that unless your wood has been stored in a dessicator, it will contain some moisture anyway. There is a lot of mumbo-jumbo about wood drying. However there may be other things going on (like oxidation of wood resins, evaporation of volatile organic compounds etc going on as wood is 'dried'. This may account for supposed magical acoustic properties. A guitar side at .080 can be soaking wet and return to 'dry'- ie in equilibrium with the moisture in the room within a matter of days. A wet, freshly-cut 4-inch plank may take several years or more to come to the same equilibrium- it all has to do with the surface area compared to the mass, etc. What generally doesn't work well is to cut very thin sections off the quarter from a green (wet) log- when the thin slabs dry they will tend to take on some peculiar and unwanted shapes. This was the reason for a question in another thread about some cocobolo that a supplier is going to cut shortly. BTW, Wayne Henderson (Clapton's Guitar book/builder) boils his BRW sides for more than 'just' 8 minutes. Of course, it helps that these guys are generally using well-quartered wood which tends to be better-behaved than a lot of the slab-cut stuff we see. It's an interesting experiment to get some wet,green, hardwood 'firewood' from your local chainsaw-wielding guy and try cutting it up into thin stuff, and watching it dry. It's better than reading all this! Cheers John |
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| Author: | WaddyThomson [ Fri Apr 13, 2007 2:40 pm ] |
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I mentioned this before in the othe thread, but in Irving Sloan's book "Classic Guitar Construction", he steeps his sides in hot water for one and a half hours, then puts them on the form under a layer of canvas. He allows them to dry for a week in a dry/hot environment using the sun or sunlamps if it isn't hot enough. He does, however, say that the success of this method depends on straight grained, well quartered wood, and that highly figured woods may fracture using his method. |
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| Author: | Sam Price [ Fri Apr 13, 2007 5:45 pm ] |
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There I was, carefully applying a damp (not dripping) cloth over my bending pipe, and Volbrecht bent his guitar sides with water issuing everwhere!!! You certainly learn new things every day! |
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| Author: | tippie53 [ Sat Apr 14, 2007 12:41 am ] |
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There is a lot of mystery about water and bending wood. Water in most cases is the medium that carries the heat. In a word it helps the wood to conduct the heat. Too much water can cause alot of issuse. I bend alot of wood , last year I bent over 250 sets . I can tell you that some woods like water and some don't. I use water more for an anti scortching. As long as the wood is wet it won't scortch and some woods like maple and other figured woods need more heat to get the thermoplastic properties of the wood to work. Boiling may be fine if you are making hay rakes and sled runners but it is hard on the thinner wood we use. I use a wide heat range from 270 to 400 to bend wood depending on the species. In most cases I am dine bending is less than 5 minutes so scortching isn't an issue. Some woods scortch easier than others , Snakewood and Lacewood scortch at low temps. Bloodwood and Paduk need allmost 400 degrees to bend consistiently. Good luck and NEVER LET A BENDER UNATTENDED john hall |
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| Author: | David Collins [ Sat Apr 14, 2007 4:53 am ] |
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The drying and seasoning of wood is also more complicated than simply measuring the moisture content. I'm certainly not an expert on forest products and wood technology, but I do know that there is difference between fresh dried wood and wood that has been seasoned. Moisture within the cells themselves can be driven out rather quickly with a kiln or dry environment. The cell walls themselves however also contain moisture which is much slower to escape, and the walls continue to dry and harden over an extended period of time. I'm not certain but it may be true that this works in reverse as well, meaning that when a seasoned piece of wood is wetted or soaked that the hardened cell walls hold thier properties and the wood does not revert to a "green" status. Like I said, I'm not an expert in this field. This theory might make some sense. It's also quite possible that I have just fabricated a convenient yet totally wrong explanation to comfort those who have spent good money on seasoned wood, only to soak it in water. I really don't know. Perhaps some of the wood vendors know a little more about this if it is an area that has received much study at all. |
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| Author: | JBreault [ Sat Apr 14, 2007 5:11 am ] |
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We do "cook" most of the water out of the sides when we bend them, right? I think the seasoning and drying have more to do with the back and top woods. And we want our sides to match the back...so, we wait and then add water to the sides when we need to bend them. That's my theory at least. |
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| Author: | JohnAbercrombie [ Sat Apr 14, 2007 7:59 am ] |
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[QUOTE=David Collins] I'm certainly not an expert on forest products and wood technology, but I do know that there is difference between fresh dried wood and wood that has been seasoned. Moisture within the cells themselves can be driven out rather quickly with a kiln or dry environment. The cell walls themselves however also contain moisture which is much slower to escape, and the walls continue to dry and harden over an extended period of time. I'm not certain but it may be true that this works in reverse as well, meaning that when a seasoned piece of wood is wetted or soaked that the hardened cell walls hold thier properties and the wood does not revert to a "green" status. [/QUOTE] David- You and I share the same 'model' about wood drying ('Great minds think alike' or 'Fools love company'-take your pick!) Most of the folks I've talked to about green woodworking and bending (chairmakers, boatbuilders) have said that no matter how long you steam a dry stick, it never bends as easily as one that is green when you put it to steam. Similarily there is a widespread (and justified IMO) feeling that air-dried or small-scale low-temp kiln-dried lumber has superior properties to commercial quick steam-kiln dried lumber. I assume that any effects from wetting sides for bending will be temporary, especially if the wood is dried fairly promptly after bending. I never get very upset if lumber (boards) on the roof rack gets rained on while I'm getting it home, for the same reason. My preference is always for quartered planks that have been air dried and stored for years in a nice attic or dry barn, but I don't often get my hands on such stuff! Cheers John |
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| Author: | JohnAbercrombie [ Sat Apr 14, 2007 8:07 am ] |
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[QUOTE=tippie53] I use water more for an anti scortching. As long as the wood is wet it won't scortch and some woods like maple and other figured woods need more heat to get the thermoplastic properties of the wood to work. Some woods scortch easier than others , Snakewood and Lacewood scortch at low temps. Bloodwood and Paduk need allmost 400 degrees to bend consistiently. john hall[/QUOTE] John- Thanks for the tips! Your experience is matched by very few folks here. I also agree that some woods (basswood,some walnut in my limited experience) don't 'like' water and seem to just fall apart into a fibrous mess if they are soaked too long. And, of course figured woods (curly and rowed grain) are a whole area of fun in themselves! Thanks again for the info about the species you mentioned. It would be great (hint, hint) if there was a list of the wetting and bending characteristics of most of the woods we commonly use for backs and sides, so we could avoid those expensive mistakes. Cheers John |
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| Author: | tippie53 [ Sat Apr 14, 2007 9:42 am ] |
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That is a good idea . Wood is a beautiful resource ,it is replentishable and can be managed. When wood cures that is different than drying. Wood can be kilned or air dried. Both do a good job. kilns are great in that they are more controlled but wood that is dried too fast can become case hardened. As wood dries and looses moisture most assume this is all there is . The facts are that the cell looses moisture and that is true , but the resins in the wood cure and harden. If anyone here ever worked oak and yellow pine you can see that in effect. old yellow pine is hard as he#$. Spruces take a while for that to happen and while heating to bend will get the free moisture out it won't get the moisture out of the resins. Well that should give you all something to think about and if we are luck we will hear from some experts and learn even more john hall blues creek guitar |
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