Weird plating on a bicentennial Kennedy half dollar 1 1

[polarprints_ak]

I'm fairly new to coin searching, I found this half dollar with a rough texture and a few patches of smooth surface.  The pictures don't really show it very well but the smooth surfaces have that bluish-gray, tarnished silver look.  Can anybody give me some insight on what's going on with this coin? thanks!

[Greenstang]

The rough texture was caused by some sort of environmental or chemical damage.    
What is the weight to two decimal points.

[polarprints_ak]

On 11/5/2023 at 12:25 PM, Greenstang said:

The rough texture was caused by some sort of environmental or chemical damage.    
What is the weight to two decimal points.

11.31 grams

[Sandon]

   The official weight for a copper-nickel clad 1976-D Bicentennial Kennedy half dollar is 11.34 grams, while the official weight for the silver clad version intended to be minted only in San Francisco is 11.50 grams. Your coin is clearly of the copper-nickel variety at 11.31 grams with some wear and/or environmental damage.  The anomalies don't resemble any known form of "mint error" of which I am aware and don't appear to be something that could have been created during the manufacturing process. The surface of the coin may have been etched by acid, although it is probably impossible to say for sure how the coin was damaged.

[RWB]

Cheap gold plating that did not bond fully to dirty/oily CuNi coin.

(Same thing can happen with baby shoes are sent out for "bronzing," or you have the cat bathed in liquid lead to get a shiny coat.)

[polarprints_ak]

On 11/5/2023 at 2:35 PM, RWB said:

Cheap gold plating that did not bond fully to dirty/oily CuNi coin.

(Same thing can happen with baby shoes are sent out for "bronzing," or you have the cat bathed in liquid lead to get a shiny coat.)

reminds me of this "silver" new hampshire state quarter I found, some poor grandma probably paid 19.95 for it plus shipping and handling from a late night tv shopping network

[VKurtB]

Well at least it's a historical record of a rock formation that no longer exists, and a motto that seems to have died also.

Edited November 6, 2023 by VKurtB

[cobymordet]

I am quite jealous of all of these crazy coins that end up on this forum.  I only get wrecked coins or rotted .  The weirdest coin I found thus far is a '53 wheat that some insufficiently_thoughtful_person painted the OBV & REV silver but failed to paint the rim as well.  Even my parking lot parties are boring. 

[powermad5000]

I think maybe a thin coating of something (paint or plating) was applied to the surface of the coin, but did not adhere to the surface in all spots and/or was not completed. I don't think it was acid dipped as that would have been too hard to control to have the acid miss certain spots as well as would have affected the overall weight by lowering it beyond mint tolerance.

Some members on here might say to try to soak the coin in acetone and see if the paint/plating comes off but be careful with the acetone as it is a pungent chemical and needs an area of fresh air venting as well as it is extremely flammable. If you are not comfortable handling acetone, I would say to just accept the coin in its condition is damaged and leave it at that.

Edited November 6, 2023 by powermad5000

[dprince1138]

This could also be plating done for the purpose of placing a coin into jewelry.  I have seen both silver and gold plating.

 

 

Edited November 6, 2023 by dprince1138

[Mike Meenderink]

The OPs posted coin shows evidence that a dilute nitric acid, dilute hydrochloric acid or dilute sulfuric acid contacted onto this coin. Those 3 acid solutions are the only kinds that have a pH higher than 10. A pH of 10 -10.5 is required to compromise the thin copper nickel plating and promote hydroxide precipitation.  The bubbling rough surface left shows evidence of further accelerated hydroxide precipitation. This is evidenced by the fact that the planchet for a 1976 Bi Centennial Half has a solid pure copper core. Copper in its pure form is compromised into hydroxide precipitation at 8.5-9.5pH. This is a lower pH than required to "dissolve" nickel . The solid copper core shows evidence of severe accelerated hydroxide precipitation due to the high pH of the acid solution easily destroying the pure copper core after struggling through the copper nickel clad layers. It was probably rinsed with water after permanently locking the coin in its present crazy condition.   

Edited November 7, 2023 by Mike Meenderink

[polarprints_ak]

On 11/6/2023 at 2:15 PM, Mike Meenderink said:

The OPs posted coin shows evidence that a dilute nitric acid, dilute hydrochloric acid or dilute sulfuric acid contacted onto this coin. Those 3 acid solutions are the only kinds that have a pH higher than 10. A pH of 10 -10.5 is required to compromise the thin copper nickel plating and promote hydroxide precipitation.  The bubbling rough surface left shows evidence of further accelerated hydroxide precipitation. This is evidenced by the fact that the planchet for a 1976 Bi Centennial Half has a solid pure copper core. Copper in its pure form is compromised into hydroxide precipitation at 8.5-9.5pH. This is a lower pH than required to "dissolve" nickel . The solid copper core shows evidence of severe accelerated hydroxide precipitation due to the high pH of the acid solution easily destroying the pure copper core after struggling through the copper nickel clad layers. It was probably rinsed with water after permanently locking the coin in its present crazy condition.   

A close up of the reeding for further context.  It seems like a botched attempt at plating it, the smooth surfaces definitely look like tarnished silver and they're capped on the edge with this discoloration. The rest definitely looks like acid damage which is also a totally awesome band name.

[Just Bob]

 

On 11/6/2023 at 5:15 PM, Mike Meenderink said:

The OPs posted coin shows evidence that a dilute nitric acid, dilute hydrochloric acid or dilute sulfuric acid contacted onto this coin. Those 3 acid solutions are the only kinds that have a pH higher than 10. 

An acid, by definition, has a PH <7. Anything with a PH higher than 7 is considered an alkaline. Even in its most dilute form, an acid cannot have a PH above neutral (7).

[EagleRJO]

On 11/5/2023 at 6:35 PM, RWB said:

Cheap gold plating that did not bond fully to dirty/oily CuNi coin.

It does look like the cheesy gold plated coins from say the Danbury or Merrick private mints with a very thin gold plating that would not affect the weight much, like the attached.  Possibly also exposed to some type of corrosive due to the damage as well as rough or dimpled appearance of the remaining plating.

[Mike Meenderink]

On 11/6/2023 at 8:27 PM, Just Bob said:

 

An acid, by definition, has a PH <7. Anything with a PH higher than 7 is considered an alkaline. Even in its most dilute form, an acid cannot have a PH above neutral (7).

What is the highest pH level of acid?

 

 

The scale has values ranging from zero (the most acidic) to 14 (the most basic). As you can see from the pH scale above, pure water has a pH value of 7. This value is considered neutral—neither acidic or basic. Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic.

[Just Bob]

On 11/7/2023 at 7:27 AM, Mike Meenderink said:

What is the highest pH level of acid?

 

 

The scale has values ranging from zero (the most acidic) to 14 (the most basic). As you can see from the pH scale above, pure water has a pH value of 7. This value is considered neutral—neither acidic or basic. Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic.

I'm not sure what your point is, but if you're thinking that acid has a pH from 0 to 14, you are reading that wrong. The term "basic" is another word for "alkaline".

[EagleRJO]

On 11/6/2023 at 6:15 PM, Mike Meenderink said:

The OPs posted coin shows evidence that a dilute nitric acid, dilute hydrochloric acid or dilute sulfuric acid contacted onto this coin. Those 3 acid solutions are the only kinds that have a pH higher than 10.

You could have just said a "strong acid" such as the example acids listed, which Bob is correct would have a very low pH in solution.  There are acids which are stronger, like perchloric acid, but not as common as those three.  And digging thru the chemistry cobwebs I think some weak acids are highly corrosive to certain metals.  But I'm not even sure why the type of acid is really an issue.

[VKurtB]

On 11/7/2023 at 7:27 AM, Mike Meenderink said:

What is the highest pH level of acid?

 

 

The scale has values ranging from zero (the most acidic) to 14 (the most basic). As you can see from the pH scale above, pure water has a pH value of 7. This value is considered neutral—neither acidic or basic. Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic.

By definition, if a thing has a pH over 7, IT CANNOT BE AN ACID. But the stuff in my stomach that occurs from reading dumb stuff on here certainly qualifies.

[cobymordet]

Where's Bill Nye The Science Guy when we need to ask why?

[powermad5000]

I feel like I have left the coin club room, went down the hall to Mr. Smith's chemistry class, and he is yelling at us again "DON'T BANG THE CRUCIBLE!"

[dcarr]

On 11/5/2023 at 4:35 PM, RWB said:

Cheap gold plating that did not bond fully to dirty/oily CuNi coin.

(Same thing can happen with baby shoes are sent out for "bronzing," or you have the cat bathed in liquid lead to get a shiny coat.)

 

On 11/6/2023 at 4:15 PM, Mike Meenderink said:

The OPs posted coin shows evidence that a dilute nitric acid, dilute hydrochloric acid or dilute sulfuric acid contacted onto this coin. Those 3 acid solutions are the only kinds that have a pH higher than 10. A pH of 10 -10.5 is required to compromise the thin copper nickel plating and promote hydroxide precipitation.  The bubbling rough surface left shows evidence of further accelerated hydroxide precipitation. This is evidenced by the fact that the planchet for a 1976 Bi Centennial Half has a solid pure copper core. Copper in its pure form is compromised into hydroxide precipitation at 8.5-9.5pH. This is a lower pH than required to "dissolve" nickel . The solid copper core shows evidence of severe accelerated hydroxide precipitation due to the high pH of the acid solution easily destroying the pure copper core after struggling through the copper nickel clad layers. It was probably rinsed with water after permanently locking the coin in its present crazy condition.   

 

It does not look "plated" or "acid-treated" to me.

The simple explanation is that it has metallic paint on it.

Soak the coin in lacquer thinner or other solvent and if it comes off, then we will know.

 

 

[The Neophyte Numismatist]

Oh man... this is a painful read.  I have a severe case of second-hand embarrassment. 

 

[EagleRJO]

On 11/7/2023 at 12:16 PM, cobymordet said:

Where's Bill Nye The Science Guy when we need to ask why?

pH is some pretty "basic" stuff ...  ... so I have no idea how he mixed that up.

[VKurtB]

On 11/7/2023 at 3:26 PM, EagleRJO said:

pH is some pretty "basic" stuff ...  ... so I have no idea how he mixed that up.

It’s kind of stuff that slips by when people “learn” (as if…) by reading independently from the internet, instead of studying a subject with a qualified educator or professor. With apologies to Elon Musk.