[pianotech] blackening rusty tunning pins

[Douglas Gregg]

For Joes sake.
I attached another photo of the rust restoration on the tuning pins.
The color balance is better on this one, though the magnification is
less. There is indeed rust on the pins on the right side. If there
were no rust, the converter would not change them to black (on the
left side). It does nothing to polished metal, or painted metal for
that matter. IF there are rusty bare spots on the painted plate, it
will also turn those spots black.

 Rust Converter is a water-based primer, containing two active
ingredients: tannic acid and an organic polymer. The first ingredient,
tannic acid, reacts with iron oxide (rust) and chemically converts it
to iron tannate, a dark-colored stable material. Tannins are a group
of water- and alcohol-soluble natural products extracted from fruits,
(oak) trees and grasses. The second active ingredient,
2-Butoxyethanol, is an organic polymer that provides a protective
primer layer. The overall chemical reaction converts rust into a
stable, black protective polymeric coating that serves as an excellent
primer for both oil and epoxy based paints. You can spray treated
tuning pins with a thin coat of  clear lacquer to make them glossy if
you like. It stays on pretty well even after several tunings.

The formula name for tannic acid is
2,3-dihydroxy-5-({[(2R,3R,4S,5R,6R)-3,4,5,6-tetrakis({3,4-dihydroxy-5-[(3,4,5-trihydroxyphenyl)carbonyloxy]phenyl}carbonyloxy)oxan-2-yl]methoxy}carbonyl)phenyl
3,4,5-trihydroxybenzoate.
 I just  thought you would want to know Joe, since you asked.

 There is also an ethanol alcohol carrier and ether propellant. So
don't smoke while spraying.

It is correct that bluing is an oxide. True gun bluing is an
electrochemical conversion coating resulting from an oxidizing
chemical reaction with iron, forming magnetite (Fe3O4), the black
oxide of iron. Black oxide provides minimal protection against
corrosion, unless also treated with oil. You might notice a thin film
of oil on a new set of blued pins. They do rust in the box anyway with
time.

None of the products in rust restorer will remain in liquid form for
more than a few minutes on the pins and it does not creep into the
pinblock. There is no oil or silicones. The ethanol and ether are gone
in seconds. The tannin reaction takes about 15 minutes so don't expect
instant blackening.  I do recommend spraying it lightly from 4
different directions in order to get an even coating without soaking
the pins unnecessarily.

Wim, fyi:
If I am cleaning up an old piano in the shop, I would use the rust
converter on the pins and afterwards for rusted strings, I use
Ballistol gun oil with a ScotchBright pad to clean the strings. The
rust comes off very easily, almost like it is dissolving. Obviously,
you can only clean about half to three quarters of the string
circumference this way, but there will remain some Ballistol residue
on the strings that will prevent further rust.

AND NO Joe, Ballistol does not creep up the strings and down the pins
to soften, rot or otherwise damage the pin block. To follow up a
previous concern about Ballistol (that I routinely use for center pins
that are sticking or sluggish), Ballistol is entirely safe for wood.
It has been used for 100 years on guns with wooden stocks that are
precision machined to fit perfectly with the steel components.
Anything that would soften or weaken gun stock wood would never have
survived the test of time. Ballistol is antimicrobial due to its basic
pH and thus prevents growth of bacteria and fungi that are the primary
cause of wood rot.  The basic pH also helps control future rust by
neutralizing amino acid from your fingers or the H2SO4 in the
environment coming out of all our catalytic converters on our cars.

I buy Ballistol on line from Midway USA.com.They have a good price and
fast delivery. I carry a spray can or two with a straw in my kit at
all times and have bulk cans in my shop too for cleaning strings or
application with a syringe.  I have no affiliation with Ballistol or
Midway USA. I just love the stuff and won't leave home without it. I
learned about it from another old piano technician who had used it for
20 years. I have used it for about 7 years. (but I'm old too)

Doug Gregg
Classic Piano Doc
Southold, NY
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