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I think I had read a post here once where some reputable builders actually use CA glue and glue the bridge on right to the finish. Can anybody who uses or knows of the this technique please elaborate a bit. I've been using CA glue more and more lately now that I trust it and I love how fast it makes things. But I cannot help feeling a little guilty gluing a bridge to the finish having repaired hundreds of cheap factory guitars that glue bridges to the finish and flake off.

I know it works on polyester finishes, possibly polyurethane .. not sure on that one .. not anything else that I know of ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

What Tony said and it's important - Rick is finishing his guitars with polyester, toughest finish that I know of that is commonly used on guitars and he does indeed glue his bridges with CA directly to the finish. I am sure that there is more of a method to this than I am aware of with the type of CA, prep, polyester finish, etc all probably contributing to his results.

Also note what Kevin G. says about what Rick does and builds in the thread that Todd provided a link to.

Thanks all, I'll take a look at that thread. I'm guessing since I use the Stew Mac water based finish it won't work which is fine no biggie been doing it this way for years anyway

There are two components here, and if you get them right then you're all set and if you don't then you're screwed:

1- Finish to wood adhesion
2- Glue to finish adhesion

So far as 1 goes, I remember a long talk I had with Kevin Ryan about polyester finishes when I was getting started (hadn't even spent my time with Al Carruth yet!). One thing that stuck in my head was he said that the polyester has such good adhesion that the only way to remove it is to literally cut it off. It doesn't chip, and you can saw a board with finish on it in half and there won't be a chipped edge. If you can peel your finish somehow (and most WB polyurethanes can definitely be peeled) then that's where your failure's going to happen.

So far as 2 goes...that's the tough part. If it were me, I'd try to do everything I could to ensure a good bond here. If you go by what the composites guys do (and they know more about gluing to thermoplastics than anyone) then you'll figure out a way to get a perfect match between the components as well as getting the surface energy of the polyester back up. The second would indicate some mild abrasion of the surface, making sure not to abrade any of the parts not under the bridge!

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services