Bronze Medals

Bruce Hickmott wrote:
On 15 Sep 2003 09:07:30 -0700, (Sean Moffatt) is alleged to
have written:


"George V. Huse, Jr." wrote in message .com...

When they are created, is the bronze shiny?

George,


*massive snippage of good stuff*



Best regards,
Sean Moffatt
Operations Manager
Hoffman Mint
www.hoffmanmint.com


Am I the only one who's really glad Sean hangs around here? Sean, excellent
post. Stujoe, you ought to archive his post!

bruce


Nope...you're not the only one. I thought it was excellent information
(and took a print out of it). I even had a quick squint at their web
site too to look at their goodies. :-)

Ian

Thank you, Sean! This is really good to know.

Sean Moffatt wrote:
"George V. Huse, Jr." wrote in message .com...

When they are created, is the bronze shiny?


George,
The bronze is "shiny" during the striking phase of the creation of a
medallion. When a bronze medallion is produced, all through out the
striking process the bronze is in a "bright" stage. When it is known
that a medal is going to be antiqued (have a patina finish applied)
the dies are normally brought to a satin type finish as compared to a
polished finish like seen on typical coin dies. The reason being is
why waste the time to polish up the die when the mirror is going to be
removed to apply the antique finish anyway. If the medal is going to
have a bright as in a coin or proof finish the dies are polished
accordingly before striking. Anyway, the satin finish on the medals
does not make them bright as your average coin would look, but it
makes the medal look rather dull without any real luster. The satin
finish is the same in the relief as well as the on the fields so there
is no real contrast between the two. With this type of process the
metal of the piece is still considered to be in a bright (unfinished)
state. The medals that require multiple strikes have to be annealed
between strikes. Just heating the medals up to soften them would
create a layer of heavy oxidation which would look like an ugly burnt
bronze patina. This oxidation would eat up the surface of the dies.
To alleviate this problem we use controlled atmosphere annealing
furnaces that typically run ammonia heated to ~1750 F. The heated
ammonia at this temp breaks down into hydrogen and nitrogen. The
hydrogen flashes off and consumes any oxygen in the furnace,
preventing oxidation on the medals, and the nitrogen keeps an inert
atmosphere around the medals until they cool to below their oxidation
tempature. This may seem like alot to go through but the end result is
ready to strike softened medallions that are still in the bright
stage. This same process in used (with some variations) for making
regular coin blanks. After the medal is fully struck up it is sent to
the finishing department where the surface of the entire medal is
preped so it will hold the oxidation. The medal in dipped in any
number of solutions depending on the color of patina desired. The
medal is then relieved (highlited) by buffing with any number of
brushes or buffs required for the different looks found on medallions.
This is done either by hand or by automatic finishing equipment
depending on difficulty of the relief and other parameters. Typically
the medal is coated in some sort of laquer to keep the antique finish
from changing (or antiqueing any further). The process is basically
the same for copper, nickel, and silver, or whatever alloy is being
utilized.

Best regards,
Sean Moffatt
Operations Manager
Hoffman Mint
www.hoffmanmint.com

--
Buzz Huse, MCSE+I, MCSE Iter Sine Fine (Journey Without End)

"These opinions/comments are entirely my own and no one else's."