Reface, don't replace. . .
Ivory Bridge Repair
© Frank Ford 2008; Photos by FF
The "before" shot:
This is a close-up of the bridge on that famous 1840s Martin "Renaissance" shape guitar.
Those nasty countersunk screw holes were just about the only nonoriginal aspect of this fine museum quality instrument.
The saddle was dovetailed into the bridge and tacked lightly with hide glue. It came off easily:
First, I made a large lightweight cardboard mask to cover the guitar top:
If you look closely, you'll see that this photo isn't exactly in sequence. I'll admit to going back to illustrate this operation after I noticed I'd forgotten to get a shot of it.
Because I really wanted to avoid any contact with the finish, I taped the cardboard mask only to the ivory bridge itself. I used my light cure dental filler to plug the holes with some ivory colored compound:
The curing light made the compound set up nice and hard in only a few seconds:
After the compound set, I used a hardwood block and some sandpaper to grind the top of the bridge relatively flat, and remove about .010" of the ivory surface.
I would be making a thin ivory cap for the bridge to hide the filled holes, so I took a thin ivory section and glued it to a backing board over a thin section of light cardboard:
Then, it was a few trips under my thickness sander to reduce the ivory to about .015" thick:
I doubt I'd have been able to remove the ivory without breaking it if I'd used double stick tape, but the cardboard parted easily allowing the ivory to come off intact:
After washing off the hide glue, I cut the ivory to rough shape and, again using hide glue, I clamped it to the sanded top of the bridge:
The bridge wasn't actually flat on top, so I used a number of light clamps to spread the pressure and make the thin ivory follow the contour.
Here it is, with the clamps removed:
I took my time, carefully trimming the delicate overhanging edges:
After some gentle sanding, contouring and polishing, the bridge has a new cap that's barely detectable because the joint between the cap and the original bridge is right at the upper corner all around:
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