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

And now seven more years...any progress?

 

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You are an optimist...Spark

 

Of course not. You're talking to the guy who spent eleven years in grad school.

 

All, without commenting on the use of coinage weight for any purpose, e.g. counterfeiting, et al, I believe the data gleaned from the Report of the Secretary of the Treasury on the State of the Finances - 1902 regarding the loss of weight over time of silver coinage, is fairly conclusive: Abrasion does cause loss of mass over time and smaller coins suffer a greater loss (by percent of original mass) than do larger coins. The findings displayed below are derived from that Report. BTW, for what it's worth (and assuming my interpretation of the output is correct; an assumption that is always suspect) the ANOVA and t-tests on these data indicated that the loss of mass (over time) effect was not random (due to "chance"), both within and between groups.

Semper Fidelis

 

The Treasury Secretary reports are on the top of my to-do list on this topic, even ahead of weighing my own coins, because those reports provide a MUCH bigger sample space (alas).

And @Fallguy, thanks for reminding me of that old, familiar feeling when you see a new publication that's threatening to scoop part of your dissertation research...

 

Great stuff

 

Regarding coin weights, I believe that better balances would be useful. The cheaper $13 or so scales are not too accurate despite their ability to display many digits. Some years ago I compared the readings from such scales with 1st specifications on mint state coins and then an ASTM (American Soc for Testing & Materials) calibrated weight set.

I found that the deviation was non-linear. E.g. small coins were under weighed and large coins were weighed too much. Consequently I bought an Ohaus analytical scale (digital) open box. The problem is that I think it only goes up to 200 grams.

 

I almost spit out my milk when I read your, "thanks for reminding me of that old, familiar feeling when you see a new publication that's threatening to scoop part of your dissertation research . . ."! Ah Yes, the good old days: You've done a ton of literature meta analysis; worked up a great research project with your Thesis Advisor; maybe even lined up the lab time and some of the equipment you'll need, when . . . BAM! You overhear a couple of clowns talking about, "did you read where so-and-so just reported his/her preliminaries on . . . ". Oh well, back to the drawing board; there's another 6 months shot! edited, why did I ever choose this field. I thought I was too old to remember that distress, but thanks to you . . . misery really does love company. BTW, in case you don't have the link, you might try https://play.google.com/books/reader?id=8mDPAAAAMAAJ&hl=en&pg=GBS.PA299 .

Semper Fidelis

 

Lucretius (99 B.C. - 55 B.C.), the Roman poet and philosopher, writing about the atom said, "the ring on the finger becomes thin beneath by wearing, ... yet what particles leave them at each moment" without us seeing them. The same is true of coins as they age.

 

Well, just give me a couple of those bags to take home and I'll let you know!

 

Whenever I purchase a bag of 90% silver coins, I give them a bath in hot soapy water to eliminate 'grey fingers', then rinse well and dry on cotton towels - next, I stack them in groups of ten for counting & weighing purposes, then weigh $10FV (250 grams when new) at a time and record the weights for my siver stack data.
From my personal observations, average weights for common 90% coins are:
Walking Liberty halves - 12.30 g. Franklin halves - 12.40 g. JFK halves - 12.49+ g.
Washington quarters - 6.19 g.
Mercury dimes - 2.46 g. Roosevelt dimes - 2.48 g.
(JFK halves show the least wear)

 

When purchasing Walkers in bulk (Apmex, BGASC, SD Bullion, etc.) the average grades are G-F, with the occasional bent, slick, gouged, tooled, hammered, polished and otherwise heavily damaged coin included (usually 2-5%) - heavily worn, nearly dateless halves are AG, while the other damaged coins can be as high as XF+, but have only metal value - each bag/roll has its own distinctive 'mix' - i've been very pleased with some, disappointed in others - it's only 90% silver plus a bit of built in premium (for Walkers and Mercs)
The 2.46 avg. wt. of Merc dimes (x 5) equates to 12.30 for Walker halves - makes sense, since they circulated at the same time

 

New spec on this one is 2.83 g and this one weighs 2.59 g for an 8.5% loss

 

So I wonder what the double eagles these guys were jiggling around in bags looked like when they were done?

 

.715 instead of .7234 for each $1 face. Almost anything beyond that is just a waste of time.

If you have uncirculated coins, treat them as .7234/$1 face. Insist on this. Accept nothing less.
If they appear heavily worn, put those into a separate pile and let the potential buyer decide what to pay. Weigh them and assume 90% of that weight is silver.



Treat everything circulated as .715. For uncirculated, treat it as .7234.
For very worn pieces, reject them. That's what I do when selling and buying.

 

Nah. When selling heavily worn coins, insist on the going rate times face value. When buying them, insist on doing it by weight.

For unworn coins, vice versa.