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Nitric acid to remove broken drillbit?

Hello all. I’ve got a drillbit about 1mm diameter bit broken off in
about .5in thick sheet of art bronze. I seem to recall some
cabalistic solution muttered about in my first studio… I think it
was nitric acid to hypercorrode the bit out? Am I constructing a
fake memory or will this work. Is there a better idea [“don’t break
bits…”]? I could drill it out with a larger bit but I want this
tinier hole.

My thanks,

As strange as it may sound, get some food-grade alum and make a
super saturated solution with water, drop the piece in and check if
in a few hours.

I use this method to remove bits o’ bits from gold & silver. The
steel vanishes mysteriously.

Simmer your piece in a solution of Alum (get it in the spice section
at the grocery store, used for making pickles) mixed into water, no
proportions, like the boric alcohol solution. Then simmer away, keep
checking it to add water so it doesn’t boil dry.



I am not sure if there would be a reaction with the bronze but if a
drill bit is broken off in gold the cure would be to boil ( or slow
simmer ) the piece in Alum. Alum should be available at your local
drug store, most likely in powdered form. Mix it with water. Try
about one to two table spoon of Alum to a pint of water. The length
of time needed depends on the size of the bit but generally 15
minutes to 1/2 hour on a slow simmer should do.

Good Luck
Greg DeMark

Not Nitric, hydrochloric. You can get it in a hardware store as
"Muriatic acid" - some is concrete etch, some is for swimming pools.
Watch the fumes!!! Nitric will eat away the bronze and leave you a
nice broken drill bit piece…

No need for nitric acid though it will work it will also attack the
bronze, just plain old sparex pickle, or alum or citric acid
solutions will all dissolve the drill bit. It will dissolve faster
if warm and even faster if the piece and solution are placed in a
plastic or glass container and placed in ultrasonic cleaner.

James Binnion
James Binnion Metal Arts