Patina vs. Bare Metal

sliderule

Greetings,

I'm starting to collect Roman Coins-Imperial Period. There are so many beautiful patinas on many of the coins; I really like some of the green hues as well as many with a "sand" patina. I have gone on many dealer sites, eBay, and Vcoins to see what is available. Haven't made any purchases yet.

There seem to be a good number of coins that display "bare metal," i.e., bright copper that glistens, especially on the high points of the design. These seem to occur more in lower-grade coins but I have noticed them even in the coins from one high-end dealer. These coins are usually brown in color, and the brown color appears very thin, not as thick as the patina of other colors.

I'm aware of issues of cleaning on modern coins, and also of American Early Coppers, having frequently used the book by Eckert et al. giving guidelines for assessing early US cents, half-cents, and select colonial coins.

Here are my questions:

1. If there are bare metal spots--does this mean it's a lower end coin? (Have these been Improperly Cleaned? I am aware that there are appropriate ways of cleaning these coins.) I suspect bare metal on early American coppers would (greatly?) decrease the value of the coin.

2. When there is a solid "brown" color throughout the coin, with no bare spots, is this a sought-after patina?

3. Given the same "grade" of coin, will a full patina make the coin more sought-after than one with bare metal spots?

4. Can photographing the coin in various positions from the light source make the bare metal spots less evident?

(Wish I had photos, but I don't have permission to use the ones I see on websites.)

I hope I've explained this well-enough.

Many thanks for reading/responding; if there is an older thread on this I couldn't find it.

JohnnyCache

I don't know enough about the subject at hand to offer any comment but wish to extend you a warm welcome to the forums here.

sliderule

That you for the welcome! That means as much to me (and maybe more) than an answer to the questions...

Sapyx

1. If an ancient bronze coin shows bare metal, then it's certainly been harshly cleaned. It's possible - indeed likely - that the coin has needed such harsh treatment, in order to be preserved or identified. But it is nevertheless a "less desirable" coin than one which did not need such treatment.

2. A "solid brown" coloration, like you would commonly find on 50 to 100 year old circulated bronze coins, is not a "natural" colour for a 2000 year old bronze coin. It is usually evidence of cleaning and re-toning. Which is not a serious crime for ancient coins, as it is with moderns. People still want it and like it, as it looks more "coin-like" than the malachite-green patina that more naturally occurs on such coins.

3. Bare metal is "ugly", but retoning it is relatively easy to do.

4. Yes.

291fifth

Learn about "bronze disease" before you start buying. You don't want coins with "bronze disease" since it will continue to spread over time.

sliderule

Thank you, Sapyx and 291.

If you don't mind--what is a "natural color" for an ancient Roman coin? Are these available in, say, the under-$150 dollar range?

And what would one look for to see if a coin has bronze disease?

This entire area is very exciting for me, and at the same time a bit confusing. There is so, so much to learn and I'll probably never learn more than .000001 percent. But this also makes it really neat--all the stuff to learn, including all of the history, is inexhaustible.

Right now I'm reading "The Inheritance of Rome: Illuminating the Dark Ages 400-1000, written by Chris Wickman and published by Viking. (I like the view that says we can include the Byzantine emperors as being, well, Roman, although the term "Romaion" seems a bit awkward.) Each of the 23 chapters brings out a main theme, so it is easier to see the entire sweep of history. Right now I seem to find it easier to see some trees than the entire forest. Some of the chapters include: Crisis and Continuity, 400-550; Wealth, exchange, and peasant society; The Caroligian century; and, of course many more.

I also have the second edition of Ancient Coin Collecting, by Wayne Sayles. The long chapter on attribution and identification is also helping me see major areas and themes in the coins themselves. I have the 2003 edition, so much of the information about buying coins has been superseded by the manner in which the Internet has developed.

Harlan Berk's book on the 100 Greatest Ancient Coins gives the reader so much good information and it's written with such enthusiasm, knowledge, and experience. I also have one of the volumes by Sear. This last book is one that is hard for me to read straight through, so I'm going back and forth on it and suspect it will make an excellent reference.

I've recently retired and it's great to have some time to devote to this part of the hobby.

Many thanks again for your helpfulness and savvy. b

sliderule

Oops--I see that you answered the "natural color" question. My bad. Sorry.

Sapyx

The worst kind of corrosion on bronze and copper coins, also known as "verdigris" or "bronze disease", is powdery and pale-green in appearance. This stuff is bad because it is "infectious" - not only will it slowly spread across and into a coin if the conditions are correct, but it can jump from coin to coin when particles of the powder break off and land on other coins.

@sliderule said:
I like the view that says we can include the Byzantine emperors as being, well, Roman, although the term "Romaion" seems a bit awkward.

They were "still the Roman Empire" in a similar sense that the present government on Taiwan is "still the Republic of China": a recognizably continuous chain of succession in government, but significantly reduced in territory, and lacking both the cultural heartland and the historic capital city. But despite this, the "Byzantines" never stopped considering themselves the "true Roman Empire", and even called their emperors "King of the Romans" - a title which "real Romans" both ancient and contemporary would have found offensive.

All of which makes it kind of difficult for coin collectors and other historians to draw a line and say "These coins are Roman, but those coins are Byzantine". Anastasius' coinage reforms of AD 498 are an excellent clean break in style, marking a logical Roman/Byzantine division for the bronze coins that also handily coincides with one of the conventional definitions of "ancient" as only going up to AD 500; thus all "Roman" coins are ancient, while all "Byzantine" coins are mediaeval. But there is no such clean break in style or fabric in the gold coinage, which continue to look very "Late Roman" for several centuries after AD 498.

sliderule

Sapyx,

Many thanks again for the lengthy and well-thought out response. I'll put it on my list (or, one might say, my "curriculum) to pay special attention to the coins slightly before and after the year 498, and with the focus of an "art historian."

One of my other "activities" is to correlate the history of philosophy as it occurred when those ancient coins were being minted. I have the nine-volume History of Philosophy by Frederick Copleston, which I used back in the day as a student. The books give a great view of Ancient Greek philosophy, and good coverage of the years 100-1100. There's alot of neat information about how the Arabic philosophers and scientists (Averroes, Avicenna) contributed to the Western and Byzantine worlds, as well as of Christian philosophy during these years. Having an understanding of Christian philosophy and theology may be of particular help with the Roman emperors Constantine and beyond and then those who were in the Byzantine world, IMHO.

I hope I didn't go off-topic with this mention of philosophy--but to me the coins are opening up important and interesting historical vistas. My long career was teaching in the social sciences and I find it refreshing to be dealing with facts and events. I sometimes wish I could have had a "classical education" in high school and college but it just wasn't part of the curriculum in the places where I went to school.

And--you saved me from wasting some money on coins with the bare metal. Their prices are so low it is tempting to get them but they really do seem out of place with the glistening bronze. It can make one look at the sparkle rather than what's on the coin.

All the best. b.