Do Long Time Buried Objects Detect Deeper?

[Michigan Badger]

I tested my DeLeon in the coin garden when it was new and I was totally disappointed.

However, after using it for some 50 hours I'm constantly saying to myself "How did it reach this?"

Now that I'm doing foundations and ghost towns I'm working over deep grass and digging deeper than ever. I'm finding bullets (30-06, 30-30, etc.) at depths of 7 to 10 inches. Have you ever seen how small a 30-06 bullet is when flattened?

My experience in field has shown me that long time buried objects detect much deeper than air or even coin garden tests. And I believe this is so no matter what brand VLF machine you use.

From what I've seen so far this summer, when it comes to coin garden testing, you can figure at least 50% more depth for long time buried silver and at least double for copper. With very old iron you can figure triple or more the depth of fresh buried pieces.

Last year I used the Minelab Excalibur 1000. I could only detect a freshly buried copper penny at about 5 3/4 inches. Later I dug an old wheat cent (ca. 1920's) at 9 inches with a loud signal (landfill area). The coin was badly corroded.

Well, what do you say?

 

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[EDDE]

im going to agree with you ....the barber i dug this weekend was at least 8 inchs (maybe more?) and under a softball sized rock!!!!a freind found a 1917 merc he reburied it(put in the hole with plug over it) so i could have a hear it.i couldnt hear it at all, it was only 4 inchs ! go figure........

 

[Michigan Badger]

im going to agree with you ....the barber i dug this weekend was at least 8 inchs (maybe more?) and under a softball sized rock!!!!a freind found a 1917 merc he reburied it(put in the hole with plug over it) so i could have a hear it.i couldnt hear it at all, it was only 4 inchs ! go figure........

That's a good story deacon, thanks. I've found this same thing many times. I've often wondered if anyone has ever done a study on this phenomenon?

 

[midas777gold]

Here's the scoop. From what I understand about VLF (any brand) detectors - when they are ground balanced they see the ground as a whole item. When detecting an object buried in the ground for a while, the object becomes part of the whole and the detector will signal because of the differences between the ground and object. Yes, a corrosion halo will allow deeper detection. If you dig a hole and freshly bury a quarter and cover it, for example, you will be lucky to get a few inches of detection depth. This is caused by the now discontinuity of the fresh hole vs the whole ground. The fresh hole and object become virtually invisible to the detector. That's why when selling a detector I do not freshly bury a coin for demonstration, cause the customer says "What!!! a DFX can't detect a quarter at 4 inches!!!!" We know the DFX will get over a foot or more on long buried quarters.

 

[cryptodave]

Agree with the previous post.
The corrosion creates the halo effect, and makes the object look larger to the detector, as metal particles are spread out over an area around the object. So, the detector can find it deeper than a freshly placed one.

Thats what I've read several times, and it seems to hold true in the field for me also.

 

[Michigan Badger]

Here's the scoop. From what I understand about VLF (any brand) detectors - when they are ground balanced they see the ground as a whole item. When detecting an object buried in the ground for a while, the object becomes part of the whole and the detector will signal because of the differences between the ground and object. Yes, a corrosion halo will allow deeper detection. If you dig a hole and freshly bury a quarter and cover it, for example, you will be lucky to get a few inches of detection depth. This is caused by the now discontinuity of the fresh hole vs the whole ground. The fresh hole and object become virtually invisible to the detector. That's why when selling a detector I do not freshly bury a coin for demonstration, cause the customer says "What!!! a DFX can't detect a quarter at 4 inches!!!!" We know the DFX will get over a foot or more on long buried quarters.

MAN! This is AWESOME! You've got me doing the happy dance!

Thanks very much for what is probably the clearest explanation on this subject I've ever read.

This really answers a whole lot of questions. While I realize there's more to THing than depth, one must has depth if one hopes to see the other capabilities of his machine in action. What good is target analysis if the detector only goes 2 inches deep?

I've been into a detector buying frenzy the last few years and it amazes me how all the detectors seem to find the same kinds of stuff at about the same depths.

I did also note one other thing I think may interest some people. The more expensive the unit, the more attention I gave to it and thus usually the more finds (with one exception). I wonder what that tells me?

Thanks again!

By the way, it kind of shoots down SOME (if not all) of these "depth wars"...doesn't it?

 

[gregl01]

The only thing i wonder is why some say you can't detect freshly buried items. Then how can I find so many coins at woodchip playgrounds I do agree that some long buried items do corrode leaving a larger image in the soil. But silver and gold do not deteriorate. So I don't believe the "halo effect" can apply to these metals. A metal detector is made to find metal right
HH
Greg

 

[cryptodave]

Greg, I'm going to use a really silly example of how this works, so don't laugh.

Take a glass of water, drop a jolly rancher in it. In a couple of hours, the water has a slight taste of the jolly rancher. It bleeds the flavor and absorbs into the surroundings....

OK, a better example is how a dead piece of protein works in soil. Lets say you buried your dead dog. The dogs muscles start to break down as protein, and the earth absorbs it. Thats why putting dead fish in a flower garden works. All the minerals and nutrients from the fish get absorbed by the soil, and used by the flowers. So the theory is that the metal object eventually starts a chemical process of breaking down, or corroding, into minerals. I don't think the halo is read by metal detectors as some people think, I personally believe it is more of a ghosting effect. The detector picks up the slight trace of the mineral and gives off a somewhat false signal. False because the item isn't as big as the detector thinks, but the item is there, in the midst of a chemical reaction to the acids in the soil.

OK, chemistry was not my strong subject, but I think I somewhat explained what happens. I think I am going to stop calling it a halo, and just call it the jolly rancher effect.

 

[Michigan Badger]

So the theory is that the metal object eventually starts a chemical process of breaking down, or corroding, into minerals. I don't think the halo is read by metal detectors as some people think, I personally believe it is more of a ghosting effect. The detector picks up the slight trace of the mineral and gives off a somewhat false signal. False because the item isn't as big as the detector thinks, but the item is there, in the midst of a chemical reaction to the acids in the soil.

WOW! Where did you guys come from?! This is great stuff!

This also explains all those holes I dug and found nothing.

 

[EDDE]

Greg most chips Ive ever dug the first few inch's are dry then the further down the wetter and more moist it gets and holds that moister longer Ive dug alum.slugs at 8 inch's and more from them.....

 

[midas777gold]

Greg, wood chips are not ground. there are no minerals to cancel, so, coin depth in wood chips is the same as coins thru air.
when you freshly bury in dirt, then the VLF problems come in.

 

[bakergeol]

It is an issue which will always be debated. I certainly believe deep iron will produce a halo effect but not coins. Think about it. Silver just doesn't dissolve away. It is just as beautiful coming out of the ground today as when it was dropped 100 years ago. If silver was corroded and then micro particles are moved to the outside of the coin, the coin would be heavily pitted and corroded. I always thought another explanation is needed as I do believe longer buried coins have an edge. Higher moisture content at depth? Deep coins are more defined in contrast to the soil around them?

Several of the manufacturers such as Minelab with the EX11 state that you can not test their detectors in air or in freshly buried soil. They say it doesn't do well without a old developed soil matrix. However I saw a published air test of an Ex11 along with other high end models and the EX11's air test depths were damn impressive.To tell you the truth I have always regarded these as sales gimmicks. If you walk into the store and pick out a high end unit and it's depth appears to be close to a much cheaper lower end unit. The salesman will then say it is MUCH DEEPER and you "Can't test it in air" or "Not good on newly buried coins". So I guess there is NO WAY to test a high end detector for depth in the shop or outside before you buy one? Yeah son, this beautiful relco model can only air test a dime at 4" but it detects those 100 year old dimes at 9".

Just my 2 cents
George

 

[catlord17]

The more reactive a metal is, the more halo effect it will give. Silver, by the way, does give a halo effect. If it didn't reactwith oxygen, then it wouldn't do much for halo. But it does. Not as much as iron, of course, or even copper, but silver does give a halo effect. Gold, on the other hand, has virtually none.

 

[Monty]

Great discussion! My experience is that silver does deteriorate after a spell, depending on the soil conditions, etc. I recently dug a silver toe ring at about six inches on a beach where the surrounding water has a high salinity. The thing was black with surface corrosion. I wiped it off with a little silver cleaner and it once again looked new, and I could read the 925 stamped into it. A very small target at best, but a very loud signal. Also I have tried to hunt along an old WPA road out in the boonies but there are so many tiny brass .22 hulls I spend all my time digging them because they are corroded and put off one heck of a signal although miniscule in size. Monty

 

[Dave N Japan]

Brass, bronze and copper base stuff should have more of a halo, siver and gold may have a little ,but very little if any,,, So I have heard

 

[Michigan Badger]

Brass, bronze and copper base stuff should have more of a halo, siver and gold may have a little ,but very little if any,,, So I have heard

I think it's not so much of a "halo" thing as it is the undisturbed soil.

But, whatever is causing it; it's true. Long time buried objects do detect much deeper than freshly buried or air tests.

Odd as that may sound it's a fact.

 

[midas777gold]

On my hunt yesterday, found a corroded merc dime down about 18 inches. Silver does corrode!!!! It had a white scaly crust over it. The copper and nickels from this site have a raised green crust. And Gold jewelry also corrodes and emits a halo. Not the gold itself, but the alloy materials within the jewelry, which could be copper, silver, nickel, etc.

 

[Michigan Badger]

On my hunt yesterday, found a corroded merc dime down about 18 inches. Silver does corrode!!!! It had a white scaly crust over it. The copper and nickels from this site have a raised green crust. And Gold jewelry also corrodes and emits a halo. Not the gold itself, but the alloy materials within the jewelry, which could be copper, silver, nickel, etc.

Very good point.

But, however it works, it's true.

Last year I bought a Minelab Excalibur and almost sent it back to Minelab to demand a refund. In my test garden (mild soil) I was getting like 5 inches max. on some coins. Then I hunted a landfill area and dug a wheat cent at extreme depth. I learned right then that Minelab (and all brands) aren't kidding us about depth. Air and freshly buried tests are almost worse than worthless.

The really bad thing isn't depth but sound. Freshly buried copper coins have a much different sound than those buried 150 years. People learning sounds from freshly buried items could learn to bypass good finds.

 

[Rusted_Iron]

And Gold jewelry also corrodes and emits a halo. Not the gold itself, but the alloy materials within the jewelry, which could be copper, silver, nickel, etc.

Odd, the hundreds of gold rings/ jewelry I’ve pulled out of the water (salt and fresh) never had the first bit of evidence to support this theory. Oh my.

Unless the gold is 24K, the alloy metals do leach out and give a halo effect. Somewhere around here there's a 14K ring that's missing a stone (cz's), and the thing looks like a piece of tarnished brass. If that were in the ground I know for sure there'd be an ion halo.

Salt water also amplifies signals. I've found this to be true at least with my VLF detector. I honestly don't know why this is, but it happens every time. A tiny piece of foil that gives a faint blip in the sand sounds like it's a whole beer can when it suddenly gets covered by salt water.

 

[Rusted_Iron]

Alloy metals do not “leach” out of gold rings or gold jewelry

Yes, they do. I'm sorry, but you're talking to the wrong person on this one. You might never have seen it personally, but that doesn't mean it won't happen.

Gold itself is soluble only in aqua regia (nitric + hydrochloric). However, the alloy components of lesser-karat gold will certainly migrate from the surface as ions, even in much milder conditions.

As for that 14k ring I have being fake, you might have a point, but I can settle that with a few chemical tests.