Question about Masking a bridge before finishing or after

[Victory Pete]

I have used the scraping of the finish method before gluing the bridge and it has worked well. Experimenting with my own guitar I am tempted to glue the bridge first on my current 2 builds. I find masking the already glued bridge and then spraying to be convenient.

[theEdwinson]

Originally Posted by Tim McKnight

Here is my method:

- Lay down two layers of 2" wide blue masking tape, covering most of the lower bout top to protect its surface.
- Locate the bridge
- Drill the outer E/e holes
- Insert pins through E/e holes to secure bridge position
- Scribe around perimeter of bridge using a surgeons scalpel, cutting through the tape and finish. Do this very lightly in a couple of passes then you can feel when you are into the wood.
- Remove the bridge
- Remove the tape below the bridge
- Rout finish off using a 1/8" down cut carbide spiral bit in a Dremel
- I start at one hole and sneak up on the wood so as not to cut into the wood BUT just remove the finish
- Work from the center outward towards the perimeter
- As you approach the perimeter tape/scribed line you can see the finish "curl" as you sneak up on the scribe line. This is the line that you do not want to cross!
- Sand the entire area with 180 grit
- Its all done free hand with a pair of magnifier goggles. This has worked well for me and I can prep for a bridge in about 10 minutes.
- Remove all the masking tape
- Attach the bridge with HHG and let it set over night before removing the clamps. BTW, you only want to use LIGHT clamping pressure or else you can deform the top and starve the joint of glue.

That's a great method, Tim. I've been using the method that Goodall Guitars has been using for years, with a slightly undercut tape mask, and removing the lacquer to the peripheral cut line with a sharp chisel. But your method sounds better.
One note though, for anyone who uses painter's masking tape for masking on nitro lacquer: Regular masking tape can quickly erode your arduously buffed and polished lacquer finish. Something in the adhesive is reactive to the lacquer. So make sure you use a lacquer-safe tape! Luthiers Mercantile sells a green 3M tape that is safe, specifically for this purpose.

[Tim McKnight]

Hi Steve,
This thread is pretty old and I no longer rout the finish off. I’ve been using .001” thick Frisket Film to mask off the bridge and fingerboard extension gluing surfaces. It adheres really well to bare wood and doesn’t allow finish to creep under the edges as some tapes can. As an added benefit, after sanding and buffing, I peel the film off and accurately measure the thickness of the finish on the top.

Victory Pete,
I would add caution to your method beacause it allows finish to form a fillet, through capillary attraction, around the edges of the bridge and fingerboard extension that is all but impossible to sand and buff level with the rest of the adjacent surfaces. Don’t ask me how I know

[Victory Pete]

Originally Posted by Tim McKnight

Victory Pete,
I would add caution to your method beacause it allows finish to form a fillet, through capillary attraction, around the edges of the bridge and fingerboard extension that is all but impossible to sand and buff level with the rest of the adjacent surfaces. Don’t ask me how I know

Hi Tim,
I have been touching up my own guitars for decades, learned many things in that time. So far my 98 HD-28 is coming out pretty good as far as leveling around the contours of the bridge. I am curious to see how it will come out in the end. Thanks for your advice.

[Victory Pete]

This is coming along nicely. I had to do some considerable level sanding around bridge where the tape left a ridge of lacquer, but all in all it was a success. I will try this method on my 2 new builds. I will be easier as I wont need to build up layers of lacquer to fill voids left from the bridge replacement.