Silver Loss from Wear on 90% Silver Coins (calculation)

Discussion in 'US Coins Forum' started by WingedLiberty, Dec 11, 2010.

  1. WingedLiberty

    WingedLiberty Well-Known Member

    Over the past year, I have acquired a large number of circulated 90% silver half dollars (Kennedys, Franklins, Walkers, and Barbers); and I wanted to answer the question of how much silver is lost on well worn 90% silver coins. An issue that I have never seen hard calculations or measurements.

    The images below are a typical coin I pulled out of each lot of coins. The condition (grades) for each lot, I believe to be as follows:

    Condition:

    - EF to AU on the Kennedys ( bought for 1.0% over spot ... $8.65 per coin in 10/2010 )
    - EF to AU on the Franklins ( bought for 2.5% over spot ... $6.58 per coin in 12/2009 )
    - F to VF on the Walkers ( bought for 3.6% over spot ... $8.95 per coin in 10/2010 )
    - G to VG on the Barbers ( bought for 22% over spot ... $11.95 per coin in 11/2010 )

    Just for comparitive purposes, the current silver melt value of a 90% silver half dollar (with no silver loss from wear) is $10.37 based on Friday's close of spot silver at $28.68 per ounce.

    180_Barber.png 180_Walker.png 180_Franklin.png 180_Kennedy.png

    I know that there have been some discussions on this board about how much silver is lost in worn 90% silver coins, so I thought I would do some weight tests.

    I took a random sample of 20 of each type of coin in the lots above and came out with these total coin weights

    Measured Coin Weights:

    - 20 Kennedys (EF/AU) weighed 251 grams
    - 20 Franklins (EF/AU) weighed 251 grams
    - 20 Walkers (F/VF) weighed 244 grams
    - 20 Barbers (G/VG) weighed 236 grams

    To convert from grams to troy ounces I used the conversion factor of 0.0322, then multiplied the troy ounce weight by 0.90 since they are 90% silver coins. So I got these silver content values per coin.

    Calculated Silver Content per Coin:

    - 1 Kennedy (EF/AU) contains 0.3631 troy ounces of silver (on average)
    - 1 Franklin (EF/AU) contains 0.3631 troy ounces of silver (on average)
    - 1 Walker (F/VF) contains 0.3530 troy ounces of silver (on average)
    - 1 Barber (G/VG) contains 0.3414 troy ounces of silver (on average)

    (It should be noted that my Redbook says these 90% silver halves contained .3617 ounces of silver when minted, so my calculation of .3631 ounces of silver on the Kennedys and Franklins based on my measured weights is showing my scale has an error of being 0.3% (one-third of one percent) too high.)

    Therefore ...

    Calculated Loss of Silver Content (%) per Coin:

    - 1 Kennedy (EF/AU) = 0% loss of silver

    - 1 Franklin (EF/AU) = 0% loss of silver
    - 1 Walker (F/VF) = 2.87% loss of silver (on average)
    - 1 Barber (G/VG) = 6.36% loss of silver (on average)


    My total weight numbers are slightly off due to calibation tolerances in my scale, however when comparing percentage losses, the numbers should be fairly accurate (since all the weights would have the same error). I'm sure it's clear to everyone that the loss of silver is related to the grade of the coin and not the type, but I separated by type only because my lots are already separated by grade.

    So the upshot is if you buy bulk 90% silver coins in the following grades take into account the silver loss when computing your price over spot:

    ***********************************

    A Generic Buying Guide for Silver Loss:

    - EF/AU there is negligable loss of silver
    - F/VF there is roughly 3% loss of silver
    - G/VG there is roughly 6% loss of silver


    ***********************************


    If anyone sees anything wrong with my math above ... or has done similar calculations, feel free to post.

    I thought that if anyone was going to be buying 90% silver coins in bulk as a cheap(er) way to buy silver in the near term, you might be helped by this analysis.

    It's nice that the 0%, 3%, 6% silver loss percentages that apply (in inverse) to the pairing of the major grades (G/VG, F/VF, EF/AU) is pretty easy to remember off the top of your head! Think of it as the "036 Rule".
     
    Skyman, DEA, wxcoin and 4 others like this.
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  3. -jeffB

    -jeffB Greshams LEO Supporter

    I love to see hard numbers. :)

    I just ordered a pair of scales from cBay (as I call the cheap Hong Kong importers on eBay), one 300g x 0.01g and one 30g x 0.001g. I'm going to try to sort some of my "junk silver" Mercurys and Washingtons by grade, and get enough of a population to get some stronger statistics.
     
    Bob Evancho likes this.
  4. Vroomer2

    Vroomer2 Active Member

    Great post, by the numbers.
     
  5. WingedLiberty

    WingedLiberty Well-Known Member

    Let me know about your scales, Jeff! Always curious about new equipment. And please post your findings. I wonder if the silver loss would follow similar percentages for smaller denominations (esp curious about dimes). I picked half dollars for my bulk purchases since halfs didnt circulate nearly as much as the dimes and quaters, so i thought they might come in slightly better condition (and have less silver loss) on average.

    Another thing I always wondered about is ... where does all the worn off silver go?

    If you think about the many many hundreds of millions of silver coins produced in this country since 1794 ... and if the well worn coins lost 6% of their silver ... there must be tens of millions of ounces of "lost" silver floating around somewhere in our environment. Makes you want to grab your shovels (or maybe wisk brooms?) and silver dust bags!!! (Perhaps some of it wears off on our hands, then we wash it into our sewer systems? Sort of a strange thought.)
     
  6. slamster17

    slamster17 Junior Member

    Good job figuring this out...good to know!
     
  7. -jeffB

    -jeffB Greshams LEO Supporter

  8. dingodonkey

    dingodonkey Junior Member

    Interesting -- this is something I think a lot of us silver hoarders have thought about but never really investigated ourselves. I wonder how the loss varies for different series/denominations with different wear patterns?
     
  9. -jeffB

    -jeffB Greshams LEO Supporter

    After a month and a half, the scales finally arrived, and it looks like they'll work out quite nicely for this.

    I don't have statistics yet, but I've found several FR-AG Mercuries that appear to have lost more than 10% of their weight, and a very worn Barber dime that's down more than 15%.

    For quarters, I found that well-worn Washingtons tend to have lost 5% or more, and a couple of dateless SLQ's were down around 8%. I also have one dateless Walker half that's down about 8%. (This assumes that they were spot-on when minted, which of course isn't necessarily true.)

    The milligram scale should indicate weight of even the lightest issues to within 0.1% or better; for halves and large-format dollars, it's better than 0.01%. I hope to collect distribution information for some collections of near-uncirculated coins, to approximate the distribution of weights as minted. (Are those tolerances quoted above hard cutoffs, or just particular thresholds in a normal distribution?)

    I did try weighing a penny before and after rubbing it on my jeans for a few seconds. The first time, it lost a milligram or two, but repeated attempts didn't show any change. I'm not particularly surprised -- weight loss from a single swipe is probably in the microgram range, if that. I'd love to have a microgram scale, but that would require more stable furniture, and you've got to start worrying about the weight of fingerprints and such. :)
     
  10. GDJMSP

    GDJMSP Numismatist Moderator

    For this to have any meaning you need to post pictures of the coins so we can see what you mean by terms like "well worn".
     
  11. -jeffB

    -jeffB Greshams LEO Supporter

    Oh, yeah, pictures will certainly be included -- so "I can't grade coins from pictures, but you can." :)
     
  12. kanga

    kanga 65 Year Collector

    Interesting exercise and informative.

    But for any coins sold by weight (bullion value) it doesn't matter what condition they're in.
    You are buying a specific weight and ignoring numismatic value.

    For coins that have reasonable numismatic value, bullion value lost to wear is not significant.

    That leaves a group of 20th century coins that in high grades are traded as numismatic items.
    And in lower grades can be considered bullion.
    A look at any reasonable catalog should easily allow a person to determine where that transition point is.
     
  13. Fifty

    Fifty Master Roll Searcher

    This is great info. It's nice to see some hard data and research. I can normally fit 20 Kennedy's and Franklins in a tube but it takes 21 walkers to fill one. Perhaps the design of earlier halves led to more surface to wear.
     
  14. -jeffB

    -jeffB Greshams LEO Supporter

    I rather suspect that the age of earlier halves led to more wear, period. :)

    I'd like to see how many AG Barbers you could fit into that tube. I'd guess that you could fit 22.
     
  15. medoraman

    medoraman Supporter! Supporter

    Agree, great post. I debated on this forum a few months ago that I experienced definite wear loss on old barbers and SL halves, and was kind of shouted down and told that I didn't. Great to see someone do the math this way and have a definitive answer.

    Thanks again.

    Chris

    P.S. Maybe now WingedLiberty you can tackle gold toning???? :)
     
  16. GDJMSP

    GDJMSP Numismatist Moderator

    Not what I said at all. But when you describe a coin as well worn, what grade is that exactly ?
     
  17. -jeffB

    -jeffB Greshams LEO Supporter

    No, no, I was just making (rather, attempting to make) a topical joke based on a contest thread (the first one I've actually entered).

    I'm getting the idea that FR02-AG03 coins can be down 10-15%. Again, I'll post images as soon as I can get them together, and I'll try to gather enough data points to constitute "statistics" rather than "anecdotes" in time.
     
    Kentucky likes this.
  18. GDJMSP

    GDJMSP Numismatist Moderator

    Fair enough. While you're at it though, weigh some F, VF and XF coins as well. Those coins have wear on them too. Just don't don't be surprised when they weigh within tolerance levels.
     
  19. -jeffB

    -jeffB Greshams LEO Supporter

    Okay, here are a few lowballers with images and weights.

    First, a pair of near-uncirculated "calibrators" -- both of these weighed high, so either they've got stuff stuck to them, or they started out heavy, or my scale AND the calibration weight are off:

    1964.jpg 2.513 g

    1963.jpg 2.534 g

    Next, some well-traveled Mercury specimens:

    1916.jpg 2.267 g

    1917.jpg 2.134 g

    I think that 1916 is a pretty solid AG03, but the 1917 is probably PO01 -- maybe "FR02 details" if you disregard the pitting, but even that's a stretch.

    Finally, a pair of Barbers in the next post.
     
    Gallienus likes this.
  20. -jeffB

    -jeffB Greshams LEO Supporter

    Okay, those Barbers:

    1892o.jpg 2.136 g

    1906.jpg 2.085 g

    So, that last one -- not too far off in grade from a lot of the Barber Dime bulk batches I see on eBay -- is down over 16% from its nominal 2.5 g weight. I'm thinking the 1906-? is probably a bit closer to FR02 than AG03 based on Photograde, but it looks like the 1892-o could almost make G04 if not for the pitting around the rim.
     
    Gallienus and Spark1951 like this.
  21. GDJMSP

    GDJMSP Numismatist Moderator

    OK. First of all there are some things that must be understood when weighing coins. One would be that any coin with pitting or corrosion is by definition going to be underweight. For if it is corroded then metal is going to be missing and if metal is missing then the coin has to be underweight, depending of course on how much is missing.

    Secondly, nobody, least of all me, denies that if a coin is worn enough that it is going to be underweight. The key there is "worn enough" and how one defines worn enough. For general purposes I define worn enough as G or less. But there will still be some few examples of G grade coins that meet weight specifications.

    My point in these discussions is this. AU coins have wear on them, but yet they all weigh within tolerance. XF coins have wear on them, but yet they all weigh with tolerance. VF coins have significant wear on them, but yet they all weigh within tolerance.

    So, is it an accurate statement to say that wear equals weight loss ? Rather obviously it is not. For if it was then all of these coins would show weight loss, but they do not. The reason they do not is because in all but the most extreme cases of wear coins do not lose weight. Instead the metal of the coins is merely squashed down and spread out by what we call wear. But the metal does not leave the coin, so there is no weight loss. Not until you get down to the extreme low grades.

    The reason this is important to understand is this. Say some collector reads these threads about coins losing weight with wear. He remembers that because it is important. Later, he has a chance to buy a coin of some rarity or value. The coin is in the VF or XF grade ranges. Wanting to be sure he is getting the genuine article he weighs the coin. But the coin is light. Then he remembers a thread like this one- coins with wear lose weight. Knowing that he goes ahead and buys the coin, paying significant money, even though it is light.

    Some years later he finds out that he was taken, that the coin was not genuine.

    Now, if the same scenario takes place but the coin is an AG grade. Then yes, the coin is probably going to be light. But even if the coin is not light there is still a chance that the coin is not genuine. Many a counterfeit, or altered coin, in any grade, will be of the correct weight. Weight alone is not a good indicator that a coin is genuine. It is merely ONE of the many indicators used to determine if a coin is genuine or not.

    That's why threads like this are so important. That's why I always stress to point out to people that wear does not mean weight loss !

    Yes wear can mean weight loss. But in far more cases than not wear does not mean that a coin will be underweight. Wear equaling weight loss is only true in some few cases. But nowhere near all of them.

    Never forget that.
     
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