<< <i>Adherents to the notion that the orange peel effect is attributable direclty to the poor annealing of the planchet stock, and applies only to copper and gold coins, to the exclusion of silver and nickel, should rethink their position as the grain size in a planchet will be coarser than normal for any metal that is insufficiently annealed, resulting in the abnormalities cited in several examples above.
Welcome to the forum.
I understand there are different types and causes, which is why I want to limit the discussion the 19th century gold and bronze (as well as silver and nickel)
Since you are in the metals business, what are the proper annealing temperatures for bronze, copper-nickel, silver and gold in the typical coinage alloys? >>
Good question which probably leans towards the science and phenomena of eutectics in some manner. The answer is most likely somewhere between their annealing temps used, time proximity to actually striking the coins, and die pressure used.
It's curious that silver wouldn't exhibit more "orange peel" given it has a lower MP than Au or Cu, which are very close (assuming they annealed using nickel as a worst case). I wonder if RWB has ever come across any early mint records on annealing temps, processes, etc.? >>
As a good rule of thumb, "process annealing" of non-ferrous alloys should be done at 50% of their melting temperatures. I have not yet run up against any unsatisfactory results following this guideline, but I'm sure there are exceptions.
I'm not familiar with annealing of coinage alloys, but the specifications should be available from the US Mint itself. Doubtless, those specifications were custom-developed within the Mint over many years experience to maximize coin detail, durability and die life, while minimizing press tonnage required.
Doubtless, those specifications were custom-developed within the Mint over many years experience to maximize coin detail, durability and die life, while minimizing press tonnage required.
Don't be so sure that the proper procedures were always followed. It is a factory. If they only used one furnace for annealing planchets, then it may have been cumbersome for them to lower the temp for bronze and gold.
<< <i>Doubtless, those specifications were custom-developed within the Mint over many years experience to maximize coin detail, durability and die life, while minimizing press tonnage required.
Don't be so sure that the proper procedures were always followed. It is a factory. If they only used one furnace for annealing planchets, then it may have been cumbersome for them to lower the temp for bronze and gold. >>
Or some employee might have been ignoring instructions to anneal different metals at different temperatures by doing them all at the same time to speed things up.
Numismatist. 50 year member ANA. Winner of four ANA Heath Literary Awards; three Wayte and Olga Raymond Literary Awards; Numismatist of the Year Award 2009, and Lifetime Achievement Award 2020. Winner numerous NLG Literary Awards.
<< <i>Wouldn't some Type 1 Standing Liberty Quarters have the orange-peel texture? >>
The question on the floor involves the orange-peel effect found on Proof gold and copper. The early Buffalo nickels, Mercury dimes, Standing Liberty quarters and Walking Liberty halves do have deliberately textured fields, but those were deliberately achieved in the preparation of the dies.
Numismatist. 50 year member ANA. Winner of four ANA Heath Literary Awards; three Wayte and Olga Raymond Literary Awards; Numismatist of the Year Award 2009, and Lifetime Achievement Award 2020. Winner numerous NLG Literary Awards.
<< <i>Wouldn't some Type 1 Standing Liberty Quarters have the orange-peel texture? >>
The question on the floor involves the orange-peel effect found on Proof gold and copper. The early Buffalo nickels, Mercury dimes, Standing Liberty quarters and Walking Liberty halves do have deliberately textured fields, but those were deliberately achieved in the preparation of the dies. >>
Do we know for sure someone at the mint did not do this on purpose too. I mean to the early gold proofs?
ORANGE PEEL - (effect) - A surface roughening (defect) encountered in forming products from metal stock that has a coarse grain size. It is due to uneven flow or to the appearance of the overly large grains usually the result of annealing at too high a temperature. Also referred to as ”pebbles" and "alligator skin".
Comments
<< <i>
<< <i>Adherents to the notion that the orange peel effect is attributable direclty to the poor annealing of the planchet stock, and applies only to copper and gold coins, to the exclusion of silver and nickel, should rethink their position as the grain size in a planchet will be coarser than normal for any metal that is insufficiently annealed, resulting in the abnormalities cited in several examples above.
Welcome to the forum.
I understand there are different types and causes, which is why I want to limit the discussion the 19th century gold and bronze (as well as silver and nickel)
Since you are in the metals business, what are the proper annealing temperatures for bronze, copper-nickel, silver and gold in the typical coinage alloys? >>
Good question which probably leans towards the science and phenomena of eutectics in some manner. The answer is most likely somewhere between their annealing temps used, time proximity to actually striking the coins, and die pressure used.
It's curious that silver wouldn't exhibit more "orange peel" given it has a lower MP than Au or Cu, which are very close (assuming they annealed using nickel as a worst case). I wonder if RWB has ever come across any early mint records on annealing temps, processes, etc.? >>
As a good rule of thumb, "process annealing" of non-ferrous alloys should be done at 50% of their melting temperatures. I have not yet run up against any unsatisfactory results following this guideline, but I'm sure there are exceptions.
I'm not familiar with annealing of coinage alloys, but the specifications should be available from the US Mint itself. Doubtless, those specifications were custom-developed within the Mint over many years experience to maximize coin detail, durability and die life, while minimizing press tonnage required.
Don't be so sure that the proper procedures were always followed. It is a factory. If they only used one furnace for annealing planchets, then it may have been cumbersome for them to lower the temp for bronze and gold.
<< <i>Doubtless, those specifications were custom-developed within the Mint over many years experience to maximize coin detail, durability and die life, while minimizing press tonnage required.
Don't be so sure that the proper procedures were always followed. It is a factory. If they only used one furnace for annealing planchets, then it may have been cumbersome for them to lower the temp for bronze and gold. >>
Or some employee might have been ignoring instructions to anneal different metals at different temperatures by doing them all at the same time to speed things up.
<< <i>Wouldn't some Type 1 Standing Liberty Quarters have the orange-peel texture? >>
The question on the floor involves the orange-peel effect found on Proof gold and copper. The early Buffalo nickels, Mercury dimes, Standing Liberty quarters and Walking Liberty halves do have deliberately textured fields, but those were deliberately achieved in the preparation of the dies.
<< <i>
<< <i>Wouldn't some Type 1 Standing Liberty Quarters have the orange-peel texture? >>
The question on the floor involves the orange-peel effect found on Proof gold and copper. The early Buffalo nickels, Mercury dimes, Standing Liberty quarters and Walking Liberty halves do have deliberately textured fields, but those were deliberately achieved in the preparation of the dies. >>
Do we know for sure someone at the mint did not do this on purpose too. I mean to the early gold proofs?
Glossary at Worthington Steel's web site
Some other infomation on Orange Peel
Orange Peel.