Thickness of final plating on U.S. Lincoln 2010 To Date Shield Cents

Thanks for checking in here !

Where can I find out, or does anyone know for sure, what the thickness is of the final pure copper plating on U.S. Lincoln (2010 To Date) Shield Cents.

I appreciate your help.

ToddB67

 

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Copper makes up only 2.5% of the weight of modern Cents and the coating is 20 microns thick. I'm sure there is an acceptable variance to this, but it is probably a pretty tight tolerance.

 

I just want to know.. why?
Is it of some importance? And I ask this question in all seriousness.

 

The figures I have seen and use are between one and two ten thousandths of an inch.

 

I'm not sure, but 20 microns is 0.000787402".

 

Thanks Kirkuleez !

After searching far and wide on the Internet, I couldn't find a credible source giving that specification.

As I collect information, I always include my sources, for future reference......this is good basic record keeping practice.

Do you mind telling me your source for that "20 microns thick" answer ?

ToddB67

 

Check out these. http://studylib.net/doc/8934984/spectrophotometric-determination-thickness-of-copper-on-a...

http://pubs.acs.org/doi/pdf/10.1021/ed070p1023

 

Kirkuleez,

That's correct ! Rounded four places to the right of the decimal would be .0008" or eight-ten-thousandths. One micron = .000039 inch. (The link and additional book source below give proofs.)

Goes without saying, .0008" is really thin ! ....a little less than .001", or less-than-one-thousandths of an inch of pure copper on modern Shield pennies. No wonder ground minerals eat through the plating and into the zinc/copper alloy planchet so relatively soon !

Link: http://practicalmachinist.com/vb/cnc-machining/how-big-micron-printable-sheet-169

Book: Machinery's Handbook, 22nd Edition, page 2424, titled "Micrometers (microns) to Microinches"

Thanks !........ToddB67

 

Kirkuleez......Not much help ! Neither site gives a straight forward answer. The one presents extensive laboratory-type tests and experiments for the student, requiring test equipment and the other requires certain credentials : Your current credentials do not allow retrieval of the full text.

Thanks anyway for trying to help !

ToddB67

 

I'm used to that small scale, I work for a high pressure pump manufacturer. Which pressures as high as 70,000 PSIG, things need to be very precise.

It gives exact formulas and procedures. I'm not sure what sort of quantitative data you need, or why you want to know, but the truth is that you may never find what you are looking for. You have to remember how electroplating works. Molecules are move from the anode to the cathode leaving a fine layer on the surface of the substrate. This process does not impart an equal layer at the molecular level, so the width of the layer will differ considerably over the area of the substrate surface.

 

Thanks Conder101 !

"Ten-thousandths" have four digits to the right, after the decimal point.

In decimals your answer would be expressed 0.0001 - 0.0002 and that's awfully thin. Kirkuleez says 20 microns, which is .0008" rounded, or 4 times what you are saying.... IMHO more believable. So where did you see your figures ? I always like to backup any technical information in my records with the source, for future reference and credibility.

ToddB67

 

paddyman98......To me, the thickness of the final plating is just as important, and should be as much a part of the specifications for a coin, as the alloys and percentages used for the planchet that are regularly given in the Red Books.

Why do the Red Books include the percentages of each metal in the alloy of a coin, it's weight, diameter and sometimes other details and then omit the thickness of the final plating, other than to say in some cases that it is pure copper ?

Surely, the Mints know and keep track of the amount of pure copper plating they put on the multiple thousands of coins they sell, so why is that information not shared with us ? It just "bugs" me that this piece of information isn't included in the Red Books and it seems impossible to find a straight answer from normal sources on the internet.

I hope this explains the "why" of my question.

ToddB67

 

The mint doesn't plate the blanks, that's done by the outside contractor to the Mint's specifications.

The mint runs them through the upsetting mill to create the proto rim and then the coinage presses.

 

Because the government statutes that define the value of the coin uses the % of the metals, both in the core as well as any cladding, the coins weight and tolerances, and the diameter. It does not give the thickness specifications of either the entire coin or the separate layers.

 

Thanks for that interesting information Burton !

However, as you know, I am looking for the thickness of the final plating in any convertible numerical measurement like microns, decimal inches or millimeters.

ToddB67

 

desertgem,

Thanks for your reply.

I guess the gov. could have expressed the amount of final plating as a percentage of the total 2.5g weight, but I guess they look at the final plating as one of the "separate layers" you mentioned.

ToddB67

 

Kirkuleez,
You get my vote ! My question finally has closure !

I found a source with high credentials that agrees with your answer of 20 microns ! Here's the Link and see the paragraph under Electroplating.
https://www.comsol.com/blogs/electroplating-u-s-mint-makes-penny/

Final result: 0.00003937007 (one micron) x 20 = 0.0007874014, or rounded up to 0.0008" (Eight-ten-thousandths of an inch).

Thanks everyone for being so patient with me during my struggle for an answer I could accept .

Apologies Kirkuleez . You were right all along !

Toddb67

 

I knew that I had seen that number somewhere before. Still, I wouldn't expect that the plating will be even across the surface. It probably averages 20 micron, but given how electroplating works, I would expect a +/-5 micron variance.

 

Kirkuleez, for my own knowledge, does the plating industry have a device that can monitor the thickness ( that thin for example) so the plating time/concentration/etc. can be adjusted on the 'fly' ? Jim

 

I'm not really sure Jim, if I had to guess, they probably just go by a weight ratio. As in for every hundred pounds of blanks being played, they would expect that 2.5 pounds of the anode would be lost.