Coin Dipping

[ECM-migration]

i just became aware that dipping coins especially modern coins is an accepted practice in the hobby...This is somewhat disturbing to me and reminds me of the unaccepted practice of bleaching trading cards...anyone have any information on this practice? thank you...

[physics-fan3.14]

It is accepted to a certain extent, on certain coins, with certain chemicals, and by certain people. Every single person has a different opinion of what is acceptable.

[World Colonial]

What's your definition of acceptable and modern?

 

If by acceptable, you mean that NGC or PCGS will grade such a coin, the answer is that sometimes they will. I have a couple of Spanish silver from the 1720's in mint state NGC holders and a Peru pillar minor 1753 NGC MS-64, all are untoned. The Peru coin looks like it has been dipped to me. Its not unattractive but it lacks the original mint brilliance. The Spanish silver shows no evidence of dipping that I can see, but its unusual for coins that are almost 300 years old to be untoned and its possible or likely that they have been skillfully dipped at one time. They do appear to have the original luster though.

 

As for "old" versus "modern", I think of modern as either being a 20th century coin forward or an issue that still circulates. Those who collect ancient or medieval coinage would consider any coin after 1500 "modern". The safe general rule from the standpoint of whether a coin will be considered acceptable or not is whether the coin generally looks like other coins from the same issue or same period. But ultimately, its subjective.

[RareSov]

My tarnished (sterling silver) florin proof was dipped by NCS

 

Does this make it bad ? absolutely not. The coin looks far far better and has nice mirrors.. why does it need to be toned ? no thanks

[World Colonial]

Yes, I agree with you in that instance. I have submitted many coins to NCS for consevation. But to some people, that might be considered a form of "doctoring" at least with some coins but it is not to me. I assume that some of the coins I have submitted to NCS have been dipped because it is the best explanation between the difference in appearance before and after I submitted the coin.

[RareSov]

Likewise

 

Patina sure has its place, and can look amazing. Coins should be dipped when they look ugly..

[ECM-migration]

When I refer to modern coins I mean Silver and Gold American Eagles as well as the Australian and China panda coins....all issues start in the 80's and 90's....

[Zoins]

A number of modern proofs acquire a haze. Dipping can remove this and is often considered very desirable.

[coinman1794]

Dipping is not the only way of making a coin brilliant. Other chemicals can be used that do not eat into the metal but create amost the same result, and they are much preferable to dipping. It's unfortunate that most people turn to dip as the first choice in coin cleaning, when it should be a last resort. Dipping creates damage on a microscopic level, and after multiple dippings, will completely strip off the mint luster.

 

Most older coins (anything pre-Morgan dollar, for sure) that are brilliant, or toned in rainbow hues, have been dipped and since retoned. Many coins have gone through this cycle multiple times over the course of centuries. However, these coins are readily certified, even with poor remaining luster. The grading services will also certify blast white coins that have obviously been recently dipped. As long as the luster has not been washed out, such a coin is technically acceptable to them.

 

That is not to say that such a coin is truly problem free. A true conservationist believes in the theory that you have a responsibility to "first, do no harm." Dipping certainly does not qualify as "doing no harm;" any method of cleaning that disturbs the metal, in fact, is problematic to a conservationist. Those who approach the hobby from this perspective will gravitate toward the coins that seem to be minimally affected by old dippings, and they will generally try to save coins from suffering the fate of dipping in the future. Yet, very few numismatists are of this sect.

[World Colonial]

On the coins I used as examples, I cannot say for sure whether they have been dipped or not, because I do not know or recall what solvent is associated with it. I have the book Coin Chemistry but not with me. With the coins I mentioned, they are untoned and all I can say is that because coins that old are usually not that color, that someone at some time posisbly might have modified them.

[RareSov]

The kookaburras can be toned, and downgrade. I think I have a toned 69 which would have got 70

 

Not worth it to me to crack and dip now really.. shame, should have been done.

[RareSov]

If you have a microscope, look for metal flow lines. These are not evident on overdipped coins, which is why the luster dies (if I remember right?)

[jackson64]

I wish that dipping removed haze from proofs !!..I've never had any luck with dipping away haze..in fact the few times that I tried, dipping made them worse..I find good old acetone ( finger nail polish remover) has the best result when gently applied via a cue-tip and then rinsed with softsoap..

[coinman1794]

If you have a microscope, look for metal flow lines. These are not evident on overdipped coins, which is why the luster dies (if I remember right?)

 

That is correct; dip removes the oxidized metal from the face of the coin, stripping luster away after multiple dips. A coin is litterally lighter after dipping, though only by a small amount.

[coinman1794]

I wish that dipping removed haze from proofs !!..I've never had any luck with dipping away haze..in fact the few times that I tried, dipping made them worse..I find good old acetone ( finger nail polish remover) has the best result when gently applied via a cue-tip and then rinsed with softsoap..

 

A proof with haze that will not come out is a coin with permanent etching into the surface. Usually this is due to normal oxidation and toning. Many such coins have already been dipped to remove heavy toning, the result of which is often that cloudy haze. It is also possible for this haze to be the result of grease being struck into the coin at the time of minting. The grease becomes part of the surface and attempting to remove it results in the same haze/etching affect previously described.

[coinman1794]

The kookaburras can be toned, and downgrade. I think I have a toned 69 which would have got 70

 

Not worth it to me to crack and dip now really.. shame, should have been done.

 

Very often, a little toning or grease staining is all that keeps a 69 out of 70 plastic. However, very few modern coins need to be dipped in order to restore their as-made appearance. Most (though not all) discoloration on moderns is because of the grease, dirt, metal dust, and the many other forms of grime that coins pick up during manufacture and distibution. These things can be dissolved away with solvents. Dip removes a layer of the coin, in contrast.

[satootoko]

acetone ( finger nail polish remover)

Fingernail polish remover frequently has additives that are potentially harmful. Pure acetone from a paint, hardware or home improvement store is a far better choice.

when gently applied via a cue-tip and then rinsed with softsoap..

Another bad idea IMHO. Q-tips, no matter how gently used, can create hairlines that will significantly lower a coin's value, and soap can leave a residue. The safest procedure is to

• 
  immerse the coiin in pure acetone in a glass dish
• turn the coin over in the acetone
• move it gently to a second glass dish containing fresh acetone
• move it gently to a dish containing distilled or deionized water
• repeat water bath
• allow to air dry on a soft cloth.

At each step the acetone can be gently swirled around.