The Difference Between Little Copper and Big Copper?

[AVXVA]

A single pre-1981 Memorial (copper/bronze) penny will usually return a 12-43 : 12-44. On the other hand, one thousand (1,000) pre-1981 Memorial (copper/bronze) pennies will usually come back 9-40, 8-40 and even 6-40. The Ferrous return drops as the mass of the target increases.

A 1/4" wide piece of copper water pipe comes back 12-45. On the other hand, a 3" piece of the exact same copper pipe comes back 1-47. (I couldn't believe this one.) Again, the Ferrous return drops as the mass increases.

Has anyone else noticed this?

Does the TID of silver and gold change as the mass of the target increases? If so, how??

Bronc

 

[moonshine]

that is really interesting, thanks for taking the time to post this. kind of makes sense, silver halfs ive seen come in at Fe of 2 to 8 or so and silver dollars are supposed to come in at Fe of 1.

 

[ironsight]

Nothing new here. The more mass of the target, the more eddy current activity, the more conductive it looks to the detector.

Puzzled by the 1000 copper memorial penny thing though.
Did you really sweep 1000 pennies?
A 1000 copper pennies ringing in at a ferrous 6 to 9 makes me think something else is going on unless i'm misunderstanding.

Can't say i ever had a copper memorial ring in with that low of ferrous ID number and i've dug up thousands of em including clad dimes, etc.
The vast majority of copper pennies except around junk or deep i've dug up ring in at anywhere around 11-13 ferrous, 39 to 46 conductive.

 

[AVXVA]

Puzzled by the 1000 copper memorial penny thing though. Did you really sweep 1000 pennies? A 1000 copper pennies ringing in at a ferrous 6 to 9 makes me think something else is going on unless i'm misunderstanding.

Yep, 1,000 pre-1981 (bronze) Memorial Lincoln pennies in a lump about the size of a large orange, and they routinely return 8-40 and even 6-40.

Mass has dramatic effects on copper, and I'm wondering if the same happens with gold and silver.

Bronc

 

[ironsight]

Curious why your're referring to them as 'bronze' memorials?
While its true that bronze is an alloy of copper and tin, technically in order to be called bronze it has to have a much higer ratio of tin to copper than an old memorial penny. They're usually referrred to as copper pennies since there is a tiny amount of tin involved in that penny alloy.

Memorial/wheat pennies, 1909 to 1982, 95% copper, 5% tin/zinc
Indian pennies, 1859 to 1864, 88% copper, 12% nickel
Indian pennies, 1864 to 1909, 95% copper, 5% tin/zinc

Think i got that right if not than someone correct!
Could be wrong, but i also seem to remember reading somewhere that some Indian dates used more tin in the alloy approaching true bronze.

Did you air test those 1000 pennies? If so, you should be getting a strong ferrous 12.
What settings/coil did you use when you tested them and how and where did you do it.
Something's not adding up here.

 

[ChicagoJohn]

Curious why your're referring to them as 'bronze' memorials?
While its true that bronze is an alloy of copper and tin, technically in order to be called bronze it has to have a much higer ratio of tin to copper than an old memorial penny. They're usually referrred to as copper pennies since there is a tiny amount of tin involved in that penny alloy.

Memorial/wheat pennies, 1909 to 1982, 95% copper, 5% tin/zinc
Indian pennies, 1859 to 1864, 88% copper, 12% nickel
Indian pennies, 1864 to 1909, 95% copper, 5% tin/zinc

Think i got that right if not than someone correct!
Could be wrong, but i also seem to remember reading somewhere that some Indian dates used more tin in the alloy approaching true bronze.

Did you air test those 1000 pennies? If so, you should be getting a strong ferrous 12.
What settings/coil did you use when you tested them and how and where did you do it.
Something's not adding up here.

Interesting! I notice that Indian head pennies read is different! Something like 12-34 to 12-36 so how its the same as wheat pennies like 95% copper and 5% tin/zinc?

 

[ironsight]

ChicagoJohn wrote:
Interesting! I notice that Indian head pennies read is different! Something like 12-34 to 12-36 so how its the same as wheat pennies like 95% copper and 5% tin/zinc?

Thats a good question. The 1859 to 1864 Indians with their 88%copper/12% nickel alloy would clearly register a lower conductive ID.
After 1864, Indians were minted with the same alloy (95%copper/5%tin-zinc) as wheats and should ID as wheats.

Only thing i can think of is that ratio of 5% tin/zinc. Could not find the exact ratio of tin to zinc anywhere on the net. Could be Indians were minted with more zinc than tin and wheats were minted with more tin than zinc. I have had some Indians ring in close to wheats but very few.

Also, the quality control of the alloys used in earlier coins might not have been as precise as the later pennies as metalurgy technology improved over the years.
All guesses at this point, if anyone knows for sure comment.

 

[OldNorthwest]

The same effect does happen with gold and silver. Perhaps you've seen a list of gold coin VDI numbers. The small gold coins ($1, $2.50) read up like pulltabs and trash, larger ones like pennies ($10) and silver dimes ($20). Only thing different there is the mass, not shape or metal composition.

 

[AVXVA]

[size=medium]Circling back around on this, I went out this weekend and replicated this experiment.

A single pre-1981 Memorial (copper/bronze) penny, buried to a depth of 3" in soil, returned a 12-43 / 12-44, with a factory coil, machine set to conduct or ferrous, multi or 1-tone, open pattern.

Ten (10) pounds of pre-1981 Memorial (copper/bronze) pennies, buried to a depth of 8" in soil, came back as a 5-34 with a factory coil, machine set to conduct or ferrous, open pattern. In TTF, the target came back as a 6-34.

Thoughts?

Bronc[/size]

 

[AVXVA]

[size=medium]Part II of the experiment was to bury 6 silver dollars, 8 silver half dollars, 8 silver quarter dollars, and 16 silver dimes in a random pile to a depth of six (6) inches in soil.

With a factory coil, machine set to conduct or ferrous, multi or 1-tone, open pattern: the target returned 5, 6 and 7 ferrous numbers (and sometimes 35) and 31, 32, 33 conductive numbers...

L-o-n-g after the coil was removed from the target, the E-Trac would settle on a 1-40 to 1-44 number.

Placing the same coins in a glass container with a ceramic lid, creating an air gap inside of two (2) inches, resulted in an extremely weak non-repeatable, almost bizarre bouncing return.

??

Bronc[/size]

 

[dbado1]

I think, part of the issue, may be that the "mass" of pennies is not one solid mass. Detectors have a difficult time IDing and even detecting multiple targets massed together even if they are of the same thing (pennies). A chain, for instance, is tough for most detectors. Monte developed a "coin purse" test with multiple coins of various types...silver, copper, etc. all together to mimic a lost coin purse. Only a few popular high end detectors can even hit it.
The large solid mass of copper with low ferrous numbers makes sense.
Another strange observation along these lines...if you have a plastic nugget bottle with multiple nuggets in it...the detector will only detect the smallest nugget.

Dean

 

[metalpopper]

A single pre-1981 Memorial (copper/bronze) penny will usually return a 12-43 : 12-44. On the other hand, one thousand (1,000) pre-1981 Memorial (copper/bronze) pennies will usually come back 9-40, 8-40 and even 6-40. The Ferrous return drops as the mass of the target increases.

A 1/4" wide piece of copper water pipe comes back 12-45. On the other hand, a 3" piece of the exact same copper pipe comes back 1-47. (I couldn't believe this one.) Again, the Ferrous return drops as the mass increases.

Has anyone else noticed this?

Does the TID of silver and gold change as the mass of the target increases? If so, how??

Bronc

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[size=large]

Indeed the 'numbers' relate to MASS.​

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The numbers relating to the MASS, depend on the DIMENSIONS of the mass's shape. AS 'seen' by the magnetic field', when it traverses the static 'silhouette' of the target below the search-coil. So its SHAPE, PROPORTIONS, the material's ELECTRICAL PROPERTIES, AND the FREQUENCIES at which the magnetic field alternates......ALL those factors contribute to the complex formula which a 'non-techie' reader can only contemplate, in any explanatory comments. ..

A coin laying 'normal' to the coil's sweep, is a simple situation
.
A coin at 'an-angle' is a more complex matter.

Imagine the complexities of a hollow pipe!

The detector's search-head sees a 'silhouette' of the target...WHICH VARIES AS THE SWEEP TRANSITS OVER/ACROSS IT.

The analysis is more complex if the target is 'bulky', compared to a uniformly shaped and relatively thin coin.

[size=large]Re TID of ANY coin changes.... as its mass changes...

The CON# increases as the 'PERCIEVED' AREA INCREASES...

FE number reduce.....AS its THICKNESS increases.

The FE# INCREASES with DEPTH...due to the soils 'thickness and 'properties'...

************************************************************** matt[/size]​

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[Philber]

Thanks for the discussion, its interesting to note. Also kinda disappointing on the jar of coins scenario with a 2" air gap. Wonder of all the caches people have found(with any detector), how many filled to the brim of the container, and how many were not completely full?

 

[metalpopper]

Nothing new here. (Don’t you believe it!)
The more mass of the target, the more eddy current activity, the more conductive it looks to the detector.
(Correct in its generality, but lacking ‘in-depth’ if applied to a specific situation. That, relates to your highlighted comments (In blue.)
[size=x-large]Puzzled by the 1000 copper memorial penny thing though.
Did you really sweep 1000 pennies?[/size]
A 1000 copper pennies ringing in at a ferrous 6 to 9 makes me think something else is going on unless i'm misunderstanding.

Can't say i ever had a copper memorial ring in with that low of ferrous ID number and i've dug up thousands of em including clad dimes, etc.
The vast majority of copper pennies except around junk or deep i've dug up ring in at anywhere around 11-13 ferrous, 39 to 46 conductive.

??????????????????????????????????????????????​

Puzzled....I'll bet you're not alone on that one.

When, (as in this instance) we talk of MASS, it is meant to relate to a SOLID, HOMOGENEOUS target......NOT a collection of individual targets...such as pennies stacked or randomly placed in a container.

So a JAR of PENNIES should not be equated to an HOMOGENEOUS, SOLID-MASS.

If you scan your NOX over such a jar of coins,,,say at the lowest single frequency...5 KHz...
Then the coins on the 'surrounding-surface' of that amalgamation, will be the ones which mostly 'receive and react'........
Those inner ‘enclosed’ coins, will be ‘shielded’.

Why?.....The outer coins ‘screen’ the ‘inner’ ones.

A jar of orderly-stacked pennies, will respond ‘a little better’ than a randomly packed jar.


Randomly orientated coins, can variously affect, and be affected, by their ‘neighbour's ’reactions.

The cumulative response is degenerative, rather than contributively productlve.

The same ‘cancelling’ effect is common in buried gold etc chains...

Where if the chain is ‘tangled’, then the response may be reduced by each individual links’s response-fields, if they’re acting at an angle to its neighbors.

A chain, is more ‘findable’ if it’s carrying solid-charms’ etc OR laying flat as if 'on display'.

A buried hoard at depth, will not sound like with a loud bang;

The top space in the jar is of no consequence.

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Hopefully, that brief account of interactive factors, may help explain some queries.....matt