Pre-War Bacon mandolin
Q: Hello I was hoping you might help me. I broke out a bit of
wood from an ebony bridge between the two E strings. A tiny, perfectly
square piece split and popped away somewhere, maybe a 16th or 32th
of an inch deep. The e strings buzz now since this tiny bit of
material flew the coop? The missing material is just the amount
of ebony between the e strings on the bridge. I was thinking of
trying to fill the void with marine tex or some other type of epoxy?
Thanks
Wendelin
A: The only replacement material you should consider is ebony.
Any lutherie will have lots of little pieces of ebony; cut offs
from guitar bridge blanks, fingerboards, violin pegs etc. I have
a box of such pieces. Get a very sharp knife. An Excel, available
at craft centers or hardware stores is best. An Exacto #11 will
work, but not as well.
Carefully, square up the bottom of the gap. Then, widen the gap
beyond the notches for the E strings. You want the strings to be
resting on new wood and not on the glue line between the new and
old. Cut and fit a piece of ebony to fit snuggly into the gap.
The bottom and ends should fit perfectly. The sticking out part
should overhang in all directions. The excess will be shaved off
after the glue dries. Make sure the grain of the replacement wood
is going the same direction as the old wood. The grain of ebony
is much less obvious than the grain of other woods.
The perfect glue is black epoxy. It dries slowly, so it capillates
deeply into the wood, and dries very hard to carry vibrations well.
The black color blends with the black of the ebony. Clear epoxy
will "lens" any gap in your joint, making it look bigger
than it is. If black epoxy or clear epoxy with nigrosine coloring
powder, can not be obtained, any wood glue will work fine. Clamp
it, wipe off squeeze-out and let it dry overnight. I then use the
sharp knife, and various files to shape the patch. The final finish
is a rubbing with OOOO steel wool. I then mark the wood with the
knife and use a .013" gauged file to cut the new string slots.
Your E strings are either .010" or .011." Cutting to
.013" gives them some breathing room. If you have no fancy,
expensive files, all this work can be done with your sharp knife.
You can even do the final finish by scraping with the sharp edge.
Here's a fun fact: Sand paper was not available until the 1800s.
All the Stradivarius violins were scraped to a lustrous shine.
Steve Mason
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