Shellac / titebond

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Sven

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Hi. I saw on one of Stewmac's newsletters or what it was how a guy put a shellac finish on a miniature guitar (no uke). He was working rapidly, finishing the guitar in a couple of days. Lots of pics and advice but I would like to know something that I couldn't gather from his description. It was just that he glued the bridge on after the third coat or something and no mention was made of scraping down the shellac to bare wood before glueing. Is it totally obvious he did that, and my question is of course; anyone ever seen titebond on shellac? Would it set, or would it, as I presume, be a rubbish joint?

I'll see if I can find the description on their site, got the link on another forum but forgot which.

Sven
 
Hehehe, this thread made me laugh. I'm just guessing there's gonna be a major mishap on the cellular level.. *POP!* *TWANG!*... I could be wrong... but I don't think so..
 
My guess is that since I haven't heard of bridges glued with shellac, coupled with the fact that the glue is formulated to bond the cells of wood yet it can't now because of the shellac barrier... my hypothesis is that the shellac and titebond will bond to each other until there is a load put on the bridge and then there will be a pop twang result certainly, it's just a matter of how long.
 
Sven, we have always masked the bridge area. I am quite sure that the bridge bond would not hold otherwise and I would not want to leave the joint unmasked and have to scrape it down to bear wood. Alternatively you can glue and then mask the bridge before finishing (or maybe scrape it afterwards, but we've never tried that).
 
I've tried it two ways, glued before finish and scraping after finish. I definitely don't like the result of gluing the bridge before finishing but scraping after finish is tedious, not unenjoyable but tedious and I really wished at the time that I had a magnifying visor, which I have now. I think I'll try the masking of the bridge area before spraying this time. My only concern is the buildup and how it will look when the bridge is in place, but a plus would be that there's no doubt that any finish has left the bond of the joint compromised in any way.... hmmmm decisions decisions...

Side note, totally unrelated. Solid spanish cedar linings bend like butter, even in the waist of the tiny soprano...
 
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Some bridges on production Guitars are glued directly on to the finish. No idea which type of glue they use but personally I'm an advocate of wood to wood contact. I have masked the area but French Polishing can leach out the adhesive from under the tape resulting in an unsightly ridge. I now prefer to scalpel around the bridge and scrape.
 
Michael N. said:
Some bridges on production Guitars are glued directly on to the finish. No idea which type of glue they use but personally I'm an advocate of wood to wood contact. I have masked the area but French Polishing can leach out the adhesive from under the tape resulting in an unsightly ridge. I now prefer to scalpel around the bridge and scrape.
Click to expand...

Welcome to the the Ukulele Underground/Luthier's Lounge, Michael.
 
Michael N. said:
Some bridges on production Guitars are glued directly on to the finish. No idea which type of glue they use but personally I'm an advocate of wood to wood contact. I have masked the area but French Polishing can leach out the adhesive from under the tape resulting in an unsightly ridge. I now prefer to scalpel around the bridge and scrape.
Click to expand...

Yep, I know of at least one of the companies that do that. It's foolish IMO and the results are seen by busy luthiers. I guess the luthiers can use the work. To me, it's not a question of if but when the joint will fail. I think I do prefer the score and scrape after the finish method.
 
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scraping

A freshly sharpened chisel with the burr still on works really well for this job but you guys knew that already.
 
I have reglued about 100 guitar bridges. Almost without exception they have been glued onto finish. The exceptions have been wood to wood glue joints where the bridge split, that is the bridge failed before the glue joint did, or very old hide glue joints where the guitar has been stored in a huimid environment. Whatever time you dave is not worth the poor joint.
 
ecosteel said:
A freshly sharpened chisel with the burr still on works really well for this job but you guys knew that already.
Click to expand...

I didn't know about the burr part, makes perfect sense though. Thanks ecosteel.
 
You can polish the burr with the spike of your burnishing iron - if it has one. But only use one sweep, otherwise you'll dull it - the burr that is.
 
:cool: Cool beans Erich. I'm just now getting my sharpening rig together.
 
I find a chisel a little 'top heavy' for scraping the bridge footprint. I use a blade from a small bull nose plane that is around 3/4" in width. I sharpen it as one would a normal plane blade ie. without a burr. That helps me to locate it in the scored line left by the scalpel.
I guess there are many methods. I do know that some makers rout a very small 'rebate' all around the edges of the underside of the bridge, effectively the very edges of the bridge 'overhang' the finish. You could probably achieve the same effect by simply filing a very tiny chamfer.
My finish of preference for a soundboard (Spruce) is a simple oil finish. Bridge glued before any finish is applied. End of problem.
 
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