Stay in Tune Vol#117
By Luthier Patrick Podpadec
I'm so glad to get up in the morning now with the windows open and the birds chirping and not hearing the furnace kicking on every 1/2 hr. The brutally cold and long winter is just a distant memory. Thank God!. Everything is in full bloom, the grass is growing at it's usual fast pace and everything is in place for a beautiful summer. I hope you are all having one.
The shop is also buzzing with repairs and remodeling ideas. I have plans on building another small building about 10'x16' to store parts an wood in. I had originally thought that I would add on to my original shop (and still may in the future), but I've decided that this new project may prove to be a little less expensive than the remodel to my existing shop.
I know that I had mentioned that I had a very large maple tree taken down and have finally got all of the wood cut up and stacked for next years heating season. The fun part is when I cut the main trunk log into lumber with my friends sawmill. My intent is to build an 8' guitar that will sit on top of the stump that is left from the tree. I will be posting pictures soon about the procedure and hope everyone likes it.
This past two weeks or so I have been doing a lot of top cracks on guitars that have suffered damage most likely do the the extra dry heat that they were exposed to from the long, hard winter we experienced. There are a few things that you must do to repair this type of problem. First you must work some glue into the crack by using either fresh warm hide glue or some yellow wood glue like Titebond.* It's important that when you do this that the edges of the crack are perfectly aligned with each other. If they're not you must remove the glue and start again. There's nothing that looks worse than a crack that has been glued up badly. The next step is to stabilize the newly glued area with a few small diamond shaped cleats under the crack. The amount of cleats depends on the length of the crack (about one for every inch). It's important that the wood grain of the cleat runs perpendicular to the wood grain of the top. This gives the cracked area strength so that it will not be able to "open" up again. At this point you probably think the repair is finished. Not yet, even though the crack looks o.k. and the repair is now stable you must add a finish material to the crack. In the past I have always used lacquer to fill in the crack. It usually takes a few or more applications of drop filling lacquer into the crack and wait a few days or up to a week for the lacquer to shrink and cure so that you can sand the area dead flat so that you can buff it out. The reason you do this is so that moisture cannot be absorbed back into the glue joint and it protects the crack from any other dirt , sweat, finger or body oils or other siliconed based cleaning supplies that may be used in the future. All of these thing can do damage to the unprotected crack and can result in opening it up again. A new trick that I have learned in the recent past is instead of using lacquer ,which takes at least a few days to cure properly before you can sand and buff it out , I can use a cyanocrylate adhesive instead, better known as "super glue".
This procedure is not as easy as it sounds. You must makes sure that you tape off, and protect the surrounding finish. It's very possible that it may cause unrepairable damage to the existing finish. I like to use the "thin" watery type because it can run down deep into the crack to fully protect it. You must build up layers of it until you are above the walls of the existing finish. What is nice about it is that there is very little waiting time for the super glue to cure and to add more to it. Even though they say it sets up in 10 seconds (which it does) I still wait at least an hour before I scrape and sand it level for buffing. So the procedure that used to take me days of cure time, I can now do in just a few hours. Another nice thing is that the super glue melts nicely into other finishes and can be sanded and buffed out to a high gloss finish that cannot be distinguished from lacquer. At least I can't see it under my magnified glasses. I still use my spray booth for lacquer (quite a bit lately) but this procedure is nice when you don't want or need to finish the whole top or a large section of the instrument.
Of course I use a strong commercial grade that is designed and formulated specifically for this type of application. I wouldn't try the "cheap" stuff that comes in those small throw away tubes that you find at the check out counter of every Dollar or hardware store. It's possible they may work, but I can't take the chance when I'm working on a good instrument and being paid for professional results. I may try the other kind some day on a inexpensive project guitar. The problem is that most "inexpensive" (read cheap) guitars are usually made with laminated tops and very rarely crack along the grain line due to humidity. When they have a crack in the top it's usually do to a "blunt trauma" situation, and because of that the cracks are much worse.
Once again I bid you all a farewell and don't forget to call me (440 474-2141) if you have any broken guitars that need to be repaired or have something to donate to the new "String Instrument Junk Yard" . And of course where ever you go please try to "Stay in Tune"
Patrick from Liam Guitars/Wood-n-Strings