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I removed a bridge on moderate value Korean built classical guitar. Discovered it was not glued onto bare wood but onto the guitar's finish (lacquer ?).

Should I glue the new bridge back onto this finish or try to take its footprint on the guitar surface down to bare wood so I have a nice wood-to-wood glue joint ?

If you advise gluing onto the existing exposed finish after I clean it up and smooth it, what glue should I use ?

And if you advise taking it down to bare wood, how do I do that ? Just sanding ? Or is there a liquid like naptha or something that will liquify the lacquer to make scraping/sanding it off to bare wood easier ?

I am (obviously) a neophyte and any advice would be much appreciated.

Best,
Bob

Bob,
If you want it to stick, you need a wood on wood glueing surface.

I scrape with razor blades until close then sand.

Good luck

One of the most common failures on acoustic guitars is the bridge comes loose. One of the most common reasons for this is the finish wasn't (adequately) removed before the bridge was attached. With lacquer I use chemical stripper, then a chisel and sanding to get to bare wood, then good quality wood glue and clamps. Make a good caul that fits over and around braces so you don't crush them - you want to apply clamping pressure to the bridge plate if there is one.

The top may have a slight dome - if so the bottom of the bridge should be sanded to match.

I'm slightly surprised that the bridge on a classical was attached to the finish - most of the time classicals are finished after the bridge is installed and it is finished too.

I am not surprised that is was glued to the finish on a Korean built guitar.

Conventional wisdom is that bridges need a wood-to-wood bonding surface. But there are builders who do quite well attaching steel string bridges to polyester finishes using CA. It would still need to be a good fit to minimize the glue line.

Many cheaper guitars have a partial footprint scraped through a thick finish to the wood inside the perimeter of the bridge, leaving a rim of finish around the outside. When they glue the bridge, they end up with a hopelessly thick glue line as the bridge rests on the rim of finish. They come off will little persuasion. They would be better just to leave the finish and glue with CA.


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