Bronze disease

thanks for ur reply..can this coin be graded by NGS or PCGS ......or it comes under environmental damage category

 

Log in or Sign up to hide this ad.

Its a fairly common dated coin only valued at a few bucks even in XF, I don`t see why you would want it grading.

 

1889 1/2 pice copper ..the greenish deposits is it verdigri or normal patina .....plz advice ...

 

By what ever name you wish to use, it is copper corrosion. The coin in its lifespan of 125 years, ( during much of which coin protection of modern use was not available), met environmental conditions which were less than perfect. All of the terms we use for corrosion such as toning, verdigris, bronze disease, carbon spots, PVC damage, are results of copper metal being degraded by other chemicals over time.

 

the coins above have patina or BD?

 

I can't give u an answer to ur question but it appears the overall consensus is not to worry about BD on ur coins. Whether it is because they are worth next to nothing or some other reason I cannot tell u. Hopefully someone else can give u a straight yes or no answer without beating around the bush.

 

I see no beaten bushes here just the same question over and over with the same answer. Bronze disease is a specific problem different from other corrosion in that it sustains itself even after having been removed from the circumstances (soil, flips, ink bottles, whatever) that created it and will continue to grow until it consumes the coin. If you get a tooth filling, the dentist first removes all the bad rot. If some is missed, the rot will return. For the rest of your life, every six months you go back to the dentist and he checks for signs of returned rot around fillings. Other coin corrosion is more like stain from drinking coffee. Whether you clean it off or not, it only gets worse if you drink more coffee.

I would still appreciate answers from a specialist in modern coins: Do you see BD in modern coins? If so, it it only on coins found in the ground (by detectorists)? BD is a matter of concern to ancient collectors. Is it something of concern with coins of 1500? When do you start seeing coins with the BD problem? Personally, I have seen few BD coins less than about 1800 years old but that is not a scientific study. I do know that they come much more frequently from coins of certain regions and times but I do not know how much of that is alloy, soil conditions in those regions or the chemicals used on the coins by finders in some places. Has there been a serious scientific study on BD? I do not know.

 

I know that some dealers/cleaners use chemicals which not only tone, but start a very quick oxidisation of the metal alloy. I have seen this 'rot' coins very quickly and its something I do not approve of or need to dabble in.

 

Many studies show that the majority of verdigris is copper carbonate which is a bluish green compound with similar color to 'bronze disease' as identified by various collectors of ancients. Copper carbonate ( and also other copper compounds such as copper sulfate which many people ae aware of) can be different amounts between greenish blue of pure copper carbonate and deeper blue of hydrated copper carbonate. In the lab we use higher heat than one gets on sand dunes of the middle east to change the color of the hydrated copper compounds in minutes from deep blue to the pure greenish blue color shown here
http://en.wikipedia.org/wiki/Copper(II)_carbonate

I have read personal communications from researchers who do identify copper carbonate as a component of verdigris on modern coins, and it seems most often to be hydrated. Ancient coins ( 2000 yrs or approx) have gone through significant weather changes ( google it) and usually variations in exposure to water as well as temp changes. Lower consistent heat over 100s or thousands of years can cause the same loss of hydration as in the lab at higher heat/faster time. If the indigenous Indians in my area had utilized copper coinage for 2000 years, I would expect to find similar corrosion ( verdigris/bronze disease ) as in the middle east/Mediterranean area.

BD is not a disease. Doug's explanation is good, as any chemical left will serve as an addition point for further reaction. I am not an ancient collector, but I would suspect the mixing of the metal was not as accurate as in modern coins. Thus an area of the metal which was more reactive would be a foci of corrosion and any recurrent effect.

Now cleaning of 'BD' seems to be legitimate for ancients, and if I did it, I would try some of the modern conservation chemicals such as Bad Thad's Verdi-care and protect the coin in a hard plastic or non-PVC flip with a dessicated storage area. I predict BD would not re-occur. IMO. I have not used Verdi-care on ancients, but I have on modern.
Chemicals to cause toning or etching ( acids) would be the opposite of what one should do for BD/corrosion .

 

Really dont seem satisfied with the fact about the coin worth next to nothing .Are they worth next to nothing ? ...if anyone thinks like this then plz give reference to this fact.I have seen coins with Verdigri on 1889 quarter rupee and its refereed as environmental damage.Patina on the other hand are safe and natural and not much damgerous as BD ....i was verifying from the experts by posting some close up pics of the coin ..the answer in the form of yes or no will be welcome from anyone who is really expert in this field or research

thank u

 

Daveydempsey has told u already its only worth a few bucks in XF condition and everyone else has told u its not BD. You keep asking the same question about the same coin. What more of an answer do u want?

 

As there are no exact definition where toning ( patina if you wish for ancients) --> verdigris ---> corrosion ( environmental damage), it is hard to determine except from experience. I would say the reverse of your coin has verdigris with loci intensifying into small deposits of corrosion ( damage), the obverse is more difficult so I would say it is mainly normal with small patches of verdigris. If I was evaluating this coin , in my mind it would be environment damage as one who goes by the worse case. Sellers might just say verdigris, as the definition is hazy.If it is one of only 100 known for instance, then it would still be worthwhile. Just enjoy it as history.

 

Whew!

Now I know that my coin here doesn't have BD, ...so I know it's totally PROBLEM-FREE (right?)

 

No disease, Just death from terminal corrosion.

 

...I am not an ancient collector, but I would suspect the mixing of the metal was not as accurate as in modern coins. Thus an area of the metal which was more reactive would be a foci of corrosion and any recurrent effect.
[/QUOTE]
Dead right on all points.

This coin doesn’t have BD, but it does show improper mixing.

 

It may dead, but hey, at least it doesn't have BD!

Like the old Army exhortation to male soldiers: "Strive for zero BD!"
(...or was it VD?)

 

that's a different coin he was referring to .