I have two in the oven right now. Cheese and peperoni on both.
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| Do you ’bake’ tops and B/S? http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=4098 |
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| Author: | bob J [ Wed Dec 14, 2005 12:18 am ] |
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I would like to know how prevelent this practice is-many I have talked to 'bake'. Would you please tell how you 'bake' and please also include temps., time and other relevent info? |
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| Author: | GregG [ Wed Dec 14, 2005 12:34 am ] |
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I bake mine at 200 degrees for 2 hours in my home oven, I then let it cool in the oven after turning it off for another couple of hours. I let the wood acclimate for a couple of days and repeat the whole process 3 times. I also put some weight on the pieces in the oven so they don't potato chip too bad. So far my experience(5 tops) is that it really improves the tone of the top, of course I'm new at this so I may be giving you really bad info. I will say that my first completed guitar sounds great and I did bake the top, so who knows. Greg |
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| Author: | Bobc [ Wed Dec 14, 2005 12:42 am ] |
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I have two in the oven right now. Cheese and peperoni on both.
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| Author: | Kevin Gallagher [ Wed Dec 14, 2005 12:55 am ] |
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I've built almost 500 guitars and have never "baked" a top or set of back and sides. I'm now pulling wood offof my stock shelf that was purchased and stored there back in 1993 so there is no need to or sense in baking them. Also, I always check the moisture content of rough lumber using a pro ligmatic insertion tester and my sawn material with a mini ligmatic to be sure that it is ready for use. I know very few luthiers who heat any of their woods before using them. In my opinion, you're just asking for trouble by doing it. Regards, Kevin Gallagher/Omega Guitars |
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| Author: | Shawn [ Wed Dec 14, 2005 2:06 am ] |
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While I do "bake" my tops, Kevin makes a good point. The reasoning behind baking your tops is that it "sets the pitch" (and other phrases people use to describe what baking tonewood does) which in essense approximates what is accomplished by aging the wood. There is good data on the benefits and there are a few good builders such as Taylor that use the process but that is a substitute for what is accomplished by time. I have tops that I have had since the 70s that are my reserve as I can not find "german" spruce of the same quality any more so I use it only for special instruments...I hold on to BRW from the same era for the same reason. The tops that I bake are ones in which I have received the wood in the last 5 years so I know it is less aged. I too feel like the process improves the tone of the wood but it is subjective and I am not hard over for or against "baking", just interested in ant difference it may make. Wood does change over time...I think it was Alan Carruth that mentioned that part of what makes old violins sound great is that the wood is just that old. I do not know anyone who bakes backs and sides...sides are baked when bent and with backs there is the debate as to how much the back contributes to the overall sound. |
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| Author: | Mattia Valente [ Wed Dec 14, 2005 3:06 am ] |
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I don't bake, but I'm pondering trying it since a lot of my tops are relatively green (they're all dated, but still). The theories I've read say it's good for two reasons: sets any pitch, and pre-shrinks the top. Brings it down to bone dry, essentially. I've heard of someone (could it have been Harry Fleischman?) baking Brazilian rosewood between two metal plates, on the theory that if that released stresses/cracked the wood, it was going to do that down the line anyway. |
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| Author: | Michael McBroom [ Wed Dec 14, 2005 3:22 am ] |
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I began baking my tops about four guitars ago, mostly to set the pitch. The wood, while stable moisture-wise, was still in tree form probably not much over a year before, so it needed something to cure the resins -- besides years of seasoning, that is. I bake my tops at 200F for 1 hour. It has been my experience so far that a single session is sufficient to set the pitch. I haven't had the need to put weights on the tops; they've stayed flat. I tried an experiment using Western redcedar that I thought I'd pass along here. I had two sets, which I cooked for an hour each at 200F. Within a day of cooking them, I shot and candled both sets, and joined one. The other set, I stored on a shelf. About a month after completing the guitar that I'd built using the set I'd joined, I inspected the set that I'd stored to see if the joint was still tight, or whether the wood had moved. It hadn't moved -- it was still nice and tight. So it appears that WRC at least is quite dimensionally stable after being baked and hat it tstays that way. Best, Michael |
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| Author: | Frank Ford [ Wed Dec 14, 2005 4:35 am ] |
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Once upon a time, Bob Taylor was talking to his pal, Bill Collings on the phone, and telling him a long story about how he discovered he could virtually prevent dryness cracks in guitar tops by baking the wood, and, in effect "pre shrinking" it. The tops would still be reactive to low humidity stress, but they would return to their original size and shape once they returned to normal environment, rather than sink and crack. Since it is such a long story, I won't repeat it here. As Bob spun his yarn, Bill listened attentively, and at the end, he said abruptly, "Sorry Bob, I have to hang up - I'm off to buy an oven." Well, that's pretty much the way Bob described the scene to me. I called down to Austin to check out the business about Collings and the oven, and ended up talking to Steve McCreary, the real head (sometimes, at least) of operations there. He confirmed the story, and said, "Yes, we've cooked all our guitar tops for years now. Our motto is 'Baked, not Fried.'" Collings and Taylor are both VERY practical guys and, believe me, they wouldn't be doing this process if it didn't make really good sense. It has NOTHING to do about changes in sound that cooking might produce, but which would difficult if not impossible to discern. Some folks bake backs, too, for similar reasons, or to straighten warped wood, or whatever. Elsworth Bush (retired at the time) told me Martin used a process they called "roasting" on Brazilian rosewood, where they pressed the backs to a heated copper plate untill pitch bubbled up out of the opposite side. Then, the backs wold take a trip through the sander before use. If memory serves, he said the reason for this process had something to do with finish adhesion. Everybody cooks the sides, when they bend them. . . |
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| Author: | Kevin Gallagher [ Wed Dec 14, 2005 5:16 am ] |
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Frank, I found it interesting back when I first heard that Bob Taylor and the guys at Collings saw fit to set up for baking. I knew Elsworth and Mike Longworth was a close friend of mine as well and we talked about the prospect of top heating and slow cooling at times when it would come up on the plant floor there at Martin. They never made the move to oven baking it though. The only wood that was heated to soften and cook out resins was Brazilian at Martin and it was only done for a short time. They would heat it up and scrape off the liquid resins as they boiled out and wipe them and then a pass through a sander to open it back up ater cooling and drying. That heated copper plate can probably still be found somewhere down there...I would bet, but I'd venture to guess that it hasn't been used in a very long time. I've always wondered if its benefits were really as deep or obvious as expressed by the few builders who use the process since i've seen guitars from several of them in the stores of dealers where humidity has been allowed to get dangerously low and the same effects are seen readily on their guitars as on guitars from builders who don't cook their woods at all. I've purchased tops that had been baked by the vendors, but never saw a difference in their workability, tone, stability or longevity, but I'm glad some folks are having success with the apllication of the process. Regards, Kevin Gallagher/Omega Guitars |
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| Author: | Tim McKnight [ Wed Dec 14, 2005 5:41 am ] |
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I have baked mine for a few years now. What I have noticed is the spruces will expel resins / pitch / golden yellow spooge stuff??? which will come out of the wood face and end grain pores when baked. Cedar and redwood don't expel this spooge. I use 180* for 1/2 hour, flip the stack and bake for 1/2 more. Shut oven off and leave wood over night. The wood is then stored and not used until it has acclimated for at least 30 days. Use a cookie sheet on the bottom rack to deflect the direct heat and place the wood on the rack above the cokie sheet. I have scorched some wood proior to using the cookie sheet. I have a stash of Sitka from 1959 and when I bake it the wood will still expel a fair amount of yellow spooge. This wood has been in an attic for 45+ years and is a wonderful carmel color all the way through 8/4 planks. Even though the wood is dry (<6% MC) the wood still has yellow spooge in it. My deflection testing has also proven the wood gets stiffer by a minimum of 8% to as much as 30%. The Q goes up as well according to testing done by Randy Reynolds and others. |
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| Author: | Frank Ford [ Wed Dec 14, 2005 7:40 am ] |
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When a spruce topped guitar is dried to near zero moisture content (think hot parked car, attic storage, etc.) the wood shrinks and the top sinks. BUT, at that low moisture, there's a general collapse of some cell structure, I suppose, and the wood will not grow back to its original size after it equilibrates to its "normal" ambient humidity. All of us who work in repair and restoration have encountered old and not so old instruments with these sunken tops. Short of releasing all the braces, and maybe even removing and reinstalling the top, there's no way to get them back to their original shape. According to Mr. Taylor's experiments, an unbraced guitar top shrinks as much as 3/16" across its width when it gets this kind of catastrophic drying. No matter how it is remoisturized (izzat a real word?) it can never grow back to its original width in its normal environment. At equalibrium in its original humidty, it gains back only half of the width loss. So, by cooking the moisture completely out, we're able to shrink the top by about a tenth of an inch - the tenth that could mean the difference between a collapsed, permanently sunken or cracked top and one that loses and gains "moisture normally." Remember, I'm only talking about abusive moisture loss. A relatively rare occurance, maybe, but, that abuse occurs often enough that Taylor, Collings and others have chosen to avoid the calamatous damage by preshrinking the tops. Surely, it's easy enough to say you shouldn't drop your guitar, cook it in a hot car, or endanger it in a number of other ways, but if a simple procedure can prevent such serious damage, I'm in favor of adding it to the list of things I'd do when I build a guitar. Like a nice stiff side brace in the flat area of a dreadnought's waist, why not do it? Time and money? Oh yeah, I almost fogot about that (not really). I assume that in Taylor's big production situation cooking would cut down on warranty top crack issues to pay for itself. |
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| Author: | Evan Gluck [ Wed Dec 14, 2005 8:13 am ] |
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I wish Martin would do this as well, in the winter my shop should be called the "crack house" as I usually have several Martins at a time in various stages of crack repair and rehumidification. Its funny I checked my records and last year did about 20 Martin crack repairs and 1 Taylor. From a repair and culinary standpoint I say bake it! 
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| Author: | Don A [ Wed Dec 14, 2005 1:39 pm ] |
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So then, its not a half baked idea <groan>! I do see one problem though, you folks try and convince my wife that I need to use the oven to bake wood. 
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| Author: | Tim McKnight [ Wed Dec 14, 2005 2:18 pm ] |
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Mary actually likes the aroma of freshly baked wood wafting through the house ;) Fate is on my side... sometimes. |
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| Author: | bob J [ Thu Dec 15, 2005 1:54 am ] |
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bump |
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| Author: | Larry Davis [ Thu Dec 15, 2005 1:20 pm ] |
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I became intriqued by this a year ago and frankly thought it was more mo-jo than a quantifiable improvement. My problem was conventional thinking in terms of kiln drying wood which has been one of my experiences. I couldn't seem to get past the notion that "baking" spruce in a 200F oven was simply kilning the wood since most if not all guitar soundboards are air dried. I was perplexed because baking in an oven lacked humidity moisture control added by means of steam or mists which keeps wood from over drying which is a dryer defect. The reported shrinkage rates of the spruce seemed in-line with what one could expect with radial cut spruce of that width depending of course on the beginning moisture content. I first saw the term "pre-shrunk" on a post by Mario, but it didn't quite make logical sense to me since wood shrinks "now" and not before "now" (if that makes sense). Mario also made the statement that the oven baked spruce did not return to it's full width after acclimating to ambient envviroments. I've read about the theory that wood cells collapse and cannot return to full size, but that didn't make logical sense since moisture would pop the cell structures back out. Again I had to be skeptical because of my conventional training with kilns. This week while researching knife vs. abrasion prepared glue surfaces I stumbled upon something in the USFS Wood Handbook that really helps me understand what might be happening with the oven baked "over dried" spruce. Wood expands and contracts due to moisture changes in the cell walls.. When wood is over dried the larger micropores of cell walls are irreversably closed off which prevents moisture from re-entering the cell walls normally. Seems the result can very well be shrunk wood that stays shrunk. This is certainly not a conclusion, but thought I'd share some eye opening (for me) thoughts on this subject. Oddly, the closed off cell walls also reduce the wettability of wood and inhibits glue from wicking into the wood resulting in a weaker glue bond. |
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| Author: | Howard Klepper [ Thu Dec 15, 2005 3:00 pm ] |
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Larry, how does "Sanforized" strike you? |
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| Author: | Addam Stark [ Thu Dec 15, 2005 3:56 pm ] |
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I baked 40 Red Spruce tops a 200F for a hour and put them on the shelf. When I get in 20 more next week, I plan to do the same. I think Franks posts say it all. |
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| Author: | Mark Tripp [ Thu Dec 15, 2005 4:09 pm ] |
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Hmmmm... VERY interesting thread! Methinks cookies won't be the only thing baking in my house this holiday season! -Mark |
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| Author: | Addam Stark [ Thu Dec 15, 2005 4:22 pm ] |
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I see on the food network that people are cooking food on cedar planks in the oven. They say it makes food taste great. So don't forget a guitar top in the kitchen. Someone try to cook a pizza or some bread on it.
Take a look, Hey Tonewood guys here is a way to get rid of your low grade cedar! Look at the prices of these things! http://www.allisawcookware.com/IBS/SimpleCat/Product/asp/pro duct-id/636962.html[/URL] |
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| Author: | Shane Neifer [ Thu Dec 15, 2005 5:35 pm ] |
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Ya but Addam, you are the crowd we love!! on behalf of "The Tonewood guys"! |
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| Author: | Addam Stark [ Thu Dec 15, 2005 6:02 pm ] |
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And I'm glad you guys bring all this wonderful wood to the guitar building world! We could not do it without you. Thanks! |
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| Author: | Steve Saville [ Fri Dec 16, 2005 11:29 am ] |
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Are there top woods that you would not bake? Redwood, walnut, koa, etc. |
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| Author: | Howard Klepper [ Fri Dec 16, 2005 6:51 pm ] |
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[QUOTE=SteveS] Are there top woods that you would not bake? Redwood, walnut, koa, etc.[/QUOTE] I hear that chestnut is best if roasted on an open fire. Sorry--couldn't resist. |
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| Author: | Steve Saville [ Sat Dec 17, 2005 11:35 am ] |
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Thanks for that Howard. I just did a set of Carpathian spruce with real good luck, so I tried a set of figured redwood. Wow that redwood warped in so many directions. I think I'll heat it up again and use more than a couple of books to hold it down. Maybe I just made some fire wood. Any good ideas? Howard, now is the time to redeem yourself! 
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