Do you consider "dipping" to be a form of "coin doctoring" ?

[James_OldeTowne]

Dipping is unnecessary to protect coins and therefore it is merely a way to improve and thus doctoring.

To me, that is a brilliant quote.

 

It neatly summarizes the whole reason to place "dipping" into the coin doctoring category (as the phrase is used, though I prefer "cosmetic alteration" or something similar).

[TonerGuy]

Thank you James....

 

Toner Guy, I pretty much agree with everything you are saying in this thread, that dipping is in almost all cases is not an acceptable practice. But, there may be exceptions out there, well actually there is no doubt there are because much of what we have to purchase has been dipped as pointed out in prior posts. So I am suggesting that it might be not as black and white as some here have argued. Now having said that, I would also argue that the practice of dipping that appears to have been so common the past, must stop now and in the future. If it does not, we will have too many rare coins that are dipped too many times. We must acknowledge the 'sins of our forebears' and recognize that in the past this was likely viewed differently, but move on with a more 'enlightened' perspective in these times. If this happens we have a better chance that future generations will have something left to collect.

 

This also must apply to human enhanced toning even in the case where TPG's consider it market acceptable.

 

Thoughts?

 

Best, HT

 

I agree completely. I think dealers and collectors should adopt a "do no harm" policy towards numismatics.

 

There is a fundamental difference between conservation (removing PVC) and restoration (dipping). In most areas of antiquities pieces that have been restored command a far less premium than those that are original. Why we in numismatics place a greater value on restored pieces is still somewhat puzzling and we should come into line with most of the other industries and their practices.

[Kurtdog]

Doctoring and conserving is like gambling and gaming. If I do it in my home with my friends, it's gambling, and it's illegal. If I do it in the poker room with a bunch of casino patrons, it's gaming, and it's legal.

[Houston Investor]

Some interesting comments. I still do not consider dipping doctoring. While it is a form of conservation it is not tooling or puttying alteration of the coin which would be doctoring.

 

Occasionally coins go bad in a slab. Then they need to be cracked out, dipped, and then submitted to a TPG for slabbing. I have about 5 that I have pulled from my inventory to put thru this process for one reason or another. Some bc of unattractive toning, others bc they are ICG, ANACS to be crossed. Each coin will be examined to determine if it needs a dip.

[Frank Provasek]

Frank and John - you've got the science all wrong!!!!

 

The sulfur, in the form of hydrogen sulfide, certainly deposits on the surface of the coin. But once on the coin, it interacts with the silver to form silver sulfide. The top layer of silver actually changes to a new compound. When you use a dip, it is this silver sulfide that is being removed - some of the silver is being stripped away. It is for this reason that luster is affected.

 

You can take a silver coin, weigh it, and then subject it to an environment where it will tone very darkly. Then dip it, and weigh it again. The coin will be measurably lighter (if you use a precise enough scale). You are actually removing silver from the surface of the coin!

 

 

You are simply posting nonsense. Thiourea is a sulfur scavenger and neither thiourea nor the sulfuric acid takes away silver. The luster is affected by thiourea and silver precipitate reactions from insufficent rinsing and perhaps iron content in the rinse water. This study details the chemistry

 

http://www.springerlink.com/content/x6352g76r3r52817/fulltext.pdf

[coinman_23885]

Frank and John - you've got the science all wrong!!!!

 

The sulfur, in the form of hydrogen sulfide, certainly deposits on the surface of the coin. But once on the coin, it interacts with the silver to form silver sulfide. The top layer of silver actually changes to a new compound. When you use a dip, it is this silver sulfide that is being removed - some of the silver is being stripped away. It is for this reason that luster is affected.

 

You can take a silver coin, weigh it, and then subject it to an environment where it will tone very darkly. Then dip it, and weigh it again. The coin will be measurably lighter (if you use a precise enough scale). You are actually removing silver from the surface of the coin!

 

 

You are simply posting nonsense. Thiourea is a sulfur scavenger and neither thiourea nor the sulfuric acid takes away silver. The luster is affected by thiourea and silver precipitate reactions from insufficent rinsing and perhaps iron content in the rinse water. This study details the chemistry

 

http://www.springerlink.com/content/x6352g76r3r52817/fulltext.pdf

 

 

In excess thiourea, the free thiourea reacts with formed solid silver-thiourea complex, and silver goes into the solution, predomi- nantly as the dimers of AgTU3 + complexes.

 

Perhaps you could explain your position a little more. The underlined portion doesn't seem to support the position that silver is never moved into the solution (i.e. removed from the coin).

[Frank Provasek]

 

Furthermore, what definition states that "sulfur contaminates coins"? That's akin to saying "carbon dioxide is a poison (contaminant)" merely because we breathe it in and out all the time. It certainly can kill us in large quantity, but it is everywhere, as one expects.

 

As far as I know, sulfur in limited quantity is an integral part of virtually every practical environment, and therefore need not be considered a "contaminant".

 

It's a contaminant if you wanted your silver coin to remain brilliant and it's now dark.

 

Silver usually tarnishes from sulfur in the AIR in the form of hydrogen sulfide gas. Except from volcanos and farts, it is not normal to be in the air. But in the industrial age it's from burning coal and oil containing sulfur.

[physics-fan3.14]

Frank, some comments:

 

1.) Not all dips are thiourea based, and even the ones that are often contain other acids to help the process.

2.) Weimar White performed experiments wherein the coin was dipped, and was measurably lighter afterwards. Like him or hate him, but I can't deny his results.

3.) Sulfur in the air is from volcanoes, farts, oil, coal, groundwater, anaerobic decomposition (swamps and marshes), and is generally always present in very low levels.

[James_OldeTowne]

Silver usually tarnishes from sulfur in the AIR in the form of hydrogen sulfide gas. Except from volcanos and farts, it is not normal to be in the air. But in the industrial age it's from burning coal and oil containing sulfur.

Frank, this is not a sensible statement. You seem to argue that sulfur in the air is somehow not admissible as "normal". But even LESS normal is refined silver in the form of coins! When was the last time someone found a coin created by nature? Why would coins somehow be more normal than sulfur molecules placed into the atmosphere by nature?? Indeed, the concentration of sulfur in the atmosphere is MUCH more "normal" than the presence of silver in refined, man-made format.

 

Also, I would appreciate it if you could address the earlier question. You assert that coin dip does not (re)move silver from the surface of a coin. If true, then why does the flowline luster dissolve when a silver coin is left in the dip for too long?

[truthteller]

Silver coins turn pretty rainbow colors due to the presence of sulfur based products such as old paper, coin boards, envelopes, etc. The presence of ambient sulfur is so small to be negligible. However, silver coins turn hard white due to ambient oxygen in the air creating a silver oxide layer, which is white, and creates a barrier against further oxidation. This is why proof silver coins from the mint will develop a white "haze" and not "rainbow" colors.

 

 

 

TRUTH

[Hard Times]

Sorry Truth but this ain't the truth. Ambient air has volatile S compounds in it, some places more than others. Eventually, silver coins will tone if left out in air. But perhaps more importantly, silver coins have copper in them, copper is even more reactive, I am guessing that most of the tone we see on typical US silver coins that is colorful is likely to be the Cu sulfide compounds because of the Cu in the coins reacting with S.

 

James I am not sure you remove pure silver from the surface when dipping in all cases, probably depends on the dip. But you remove the 'tarnish', which is made up of compounds composed of silver and copper derived from the coin surfaces, and O and S from the air. Because said silver and copper came from the coin, then when removing the tarnish, you essentially remove the metal that was bound up in the tarnish which was originally in the coin. Repeated cycles of dip/tone over years, decades, or centuries will ultimately remove enough metal in the form of multiple tarnish production events to do as you say, reduce the surface qualities such as strong metal flow lines. That is usually why dipping once can be okay..... dipping more times, well........