Silver vs. Clad
Entry posted by Rayshield ·
Ever wonder why silver UC proofs look better than nickel-clad UC proofs...
I was entering a clad PFUC70 clad dime today and thought it didn't look as good as its silver companion. I noticed that clad was a 1 to 4 shot at 70 vs. 1 to 2 shot for silver. While, this is not the case for all certified coins, there is a difference that can be accounted for (with some help from the internet and engineering experience).
Let's look at coins from a material property standpoint. For general discussion I am leaving out other factors that may affect coin appearance, i.e. toning, die strikes/pressure, coin detail, etc.)
Nickel may be lighter per ounce, but it is a more brittle and stronger metal (Tensile strength = ~300 MPa, Elasticity Modulus = ~200 MPa, Shear at ~75 GPa).
Silver is more dense with more malleable properties (tensile strength = ~140 MPa, Elasticity Modulus = ~75 MPa, Shear at ~28 Gpa).
Looking past the numbers.....If equal force was applied to a silver or nickel planchet, silver would have the deeper, sharper image. In circulation though, silver will wear faster than nickel.
In addition, silver maintains a higher reflectivity coefficient than nickel when exposed to visible light (i.e., 0.9 silver vs. 0.4 nickel , 1 = perfect mirror).
With that bit of information, silver is closer to being a perfect mirror for light. So as you look at the coin under the same light source, silver will appear brighter and more cameo like compared to its nickel-clad companion.
Pretty easy to tell which one is silver...
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