Ground vs. air test True or False

[Jason in Enid]

Soooo, according to YOU (respectfully), it is impossible for a coin to leach metals into the surround soils (respectfully) creating a larger "footprint", but disturbing the soil can make it impossible to see the same coin (respectfully). What a joke (respectfully).

[Mike Scott]

Originally Posted by Jason in Enid

Soooo, according to YOU (respectfully), it is impossible for a coin to leach metals into the surround soils (respectfully) creating a larger "footprint", but disturbing the soil can make it impossible to see the same coin (respectfully). What a joke (respectfully).

Hi Jason,

First off I never said 'impossible' I would say highly unlikely......

Is not just me that says it-Much of this is according to David Johnson Chief Design Engineer at First Texas Products-he has done or led others on most of the new Fisher and Teknetics models along with having redone many of the current BH. He used to be with the original Fisher back in the 80's creating the 'X' and 'CZ' series, then Whites for MXT, GMT and DFX and Tesoro with the Diablo and Lobo which are still best sellers today. He is very well respected in the metal detecting industry for around 30 years.
He is an expert on dirt, targets and how they affect signals on metal detectors. Like I said I used to believe in the halo theory for many years until I learned differently from other industry insiders and did some experimentations of my own reinforcing that it does not exist.

I would like to hear from someone else inside the detector industry about the 'halo' with some facts to back it up---and not from a manufacturers marketing department. I don’t think its going to happen.....

The 'halo' effect is a convenient explanation for how ground can affect signals. The masses have accepted it over the years but it remains just a theory that many very knowledgeable scientific engineers feel does not hold water.
I will try and find some of the information from David Johnson to post under this thread.


Mike

[sllingshot47]

I like the "ole timers" like Karl Von Mueller who "electrified" the ground with ground probes from an old crank phone to increase the halo effect by ionizing the ground. They were able to find deep coins with the old technology. They also found the atmospheric conditions caused better or poorer results on certain days. Again, respectfully.

[YosemiteDig]

Originally Posted by Mike Scott

Hi Jason,

First off I never said 'impossible' I would say highly unlikely......

Is not just me that says it-Much of this is according to David Johnson Chief Design Engineer at First Texas Products-he has done or led others on most of the new Fisher and Teknetics models along with having redone many of the current BH. He used to be with the original Fisher back in the 80's creating the 'X' and 'CZ' series, then Whites for MXT, GMT and DFX and Tesoro with the Diablo and Lobo which are still best sellers today. He is very well respected in the metal detecting industry for around 30 years.
He is an expert on dirt, targets and how they affect signals on metal detectors. Like I said I used to believe in the halo theory for many years until I learned differently from other industry insiders and did some experimentations of my own reinforcing that it does not exist.

I would like to hear from someone else inside the detector industry about the 'halo' with some facts to back it up---and not from a manufacturers marketing department. I don’t think its going to happen.....

The 'halo' effect is a convenient explanation for how ground can affect signals. The masses have accepted it over the years but it remains just a theory that many very knowledgeable scientific engineers feel does not hold water.
I will try and find some of the information from David Johnson to post under this thread.


Mike

Great stuff man. Why is the pinpoint on a coin 90% of the time, 20x larger than the coin itself. For it to be 2-3x the size of the coin, you can detune over the target for an exact pinpoint; but why 20x larger on the first pinpoint attempt?

[woodstock]

Man are you wrong on this subject. I've been detecting for over 28 years and the HALO effect that you say is a myth is real. If you want to come over to my place and run your detector in my large (and dated) test garden you'll see. I have 3 different rolls of various coins and scrap buried from 4 - 8- 12 years (or as long as I've been living where I live) and they are all buried a 8 inches in hard packed (hammered) soil so there is little depth change from age. I have faint signals on all the 4 year coins, better on the better on the 8 and even more solid on the 12. If the Halo effect was an urban legend then explain this and your proof that it is because I have the proof in my back yard. And when the ground is wet, all signals are stronger.
All metals will degrade into the soil, like the green you'll find on a IH penny. That green on the penny from years of being buried has created a larger halo around the penny. I've dug IH penny's at 10" in the old days that hit harder than lincolns at 6". And silver does this too.
Most expect that a halo should still be there after the coin was removed and because it's not they say like you that it doesn't exist. But they don't realize that once the coin is gone and the dirt displaced the halo is displaced as well.
So say what you want but when you do explain to all of us why your right. And then explain why a 125 year old coin buried at 10" will sound off better that a 50 year old coin at a shallower depth ? When you can convince me with your explanation why they don't exist then I'll believe you. And then my test garden and many others gardens mean nothing. IMHO, Woodstock

Originally Posted by Mike Scott

The only metal that creates a detectible halo and appears to look larger is iron

Gold, silver, brass, bronze, and copper do not a create a significant enough increase in size or halo to detect targets any deeper as some have theorized over the years.

The halo effect is an ‘urban legend’ or myth in the metal detecting world.

Mike

[woodstock]

No Jason that's not what happens, a halo doesn't block your detector from seeing the coin but in fact it helps. The soil around the object gets leached by the oxidation of the object. Sometimes you can see this when you pop a coin out of the ground like a old IH penny. the imprint around the IH will be green itself. This is the leak caused by the copper and this is what makes it appear larger and get hit deeper that a newer penny at the same depth. And as far as those engineers they can't prove or disprove it. And even if they could they shoot themselves in the foot if they were to say it did. That's because then all there "new" detectors would have the same depth as the old ones. They depend on users to get the latest and best when in fact detectors depth have not changed much in almost thirty years but what has changed is that now the discriminate mode can ID without "blocking out the discriminated signal" . Therefore we now have the ability to detect without "nulling out" the whole area and we're finding more targets that we could before. Today we can also ID in all metal modes that was impossible 30 years ago and again because of the advances in tech. I dismiss the engineers opinions because I've been there and seen it and just because it doesn't work out on paper doesn't mean it doesn't exist, it just means they can't explain why it does. Science isn't exact and is disproved every day. Nothing is worse than believing bad science. IMHO, Woodstock

Originally Posted by Jason in Enid

Soooo, according to YOU (respectfully), it is impossible for a coin to leach metals into the surround soils (respectfully) creating a larger "footprint", but disturbing the soil can make it impossible to see the same coin (respectfully). What a joke (respectfully).

[woodstock]

Yes, I remember Compass made rods that you could sick in the ground and it would boost the coins halo. But they were only on the market for a short time...maybe they were removed for a good reason. If they were used continually we'd have nothing left to find and the manufactures would have gone "belly up". IMHO, Woodstock

Originally Posted by sllingshot47

I like the "ole timers" like Karl Von Mueller who "electrified" the ground with ground probes from an old crank phone to increase the halo effect by ionizing the ground. They were able to find deep coins with the old technology. They also found the atmospheric conditions caused better or poorer results on certain days. Again, respectfully.

[woodstock]

You are 100% correct and those who know more ,dig more ! IMHO, Woodstock

Originally Posted by DiggerDug

If a detector air test a coin at say 8", that is the maximum range it will find that particular coin. Air is the least amount of resistance. So there is no way it would find that coin any deeper in soil of any kind. BUT if the coin has been there a while and has chemically bonded with the surounding soil or clay then it's silhouette will appear larger to the detector. And it will be detected deeper even though it's the same coin you air tested. If this was not the case then freshly buried coins could be picked up easily but they are not.

[Jason in Enid]

Originally Posted by woodstock

No Jason that's not what happens, a halo doesn't block your detector from seeing the coin but in fact it helps. The soil around the object gets leached by the oxidation of the object. Sometimes you can see this when you pop a coin out of the ground like a old IH penny. the imprint around the IH will be green itself. This is the leak caused by the copper and this is what makes it appear larger and get hit deeper that a newer penny at the same depth. And as far as those engineers they can't prove or disprove it. And even if they could they shoot themselves in the foot if they were to say it did. That's because then all there "new" detectors would have the same depth as the old ones. They depend on users to get the latest and best when in fact detectors depth have not changed much in almost thirty years but what has changed is that now the discriminate mode can ID without "blocking out the discriminated signal" . Therefore we now have the ability to detect without "nulling out" the whole area and we're finding more targets that we could before. Today we can also ID in all metal modes that was impossible 30 years ago and again because of the advances in tech. I dismiss the engineers opinions because I've been there and seen it and just because it doesn't work out on paper doesn't mean it doesn't exist, it just means they can't explain why it does. Science isn't exact and is disproved every day. Nothing is worse than believing bad science. IMHO, Woodstock

I think you need to re-read what I posted. I never said a halo blocked the signal. I said the same thing you posted.

[Lightningjack]

Does lead leave a halo, the only reason I'm asking is because I've dug CW bullets way deeper then any coin & there almost always a solid tone with good VDI's... Just curious if the halo is why lead reads so much better in the ground then other metals... Thanks...

[Mike Scott]

Happy New Year all!


Here is some of that David Johnson information;

-----------------------------------------------------------------------------------

The digging of any target out of its matrix can disturb the 'lay of the land' and therefore the response of the metal detector. This can give someone an impression there was a "halo" that was disturbed when in most cases it was the uniformity of the matrix that was disturbed by the digging.
In rocky or already disturbed soil, the matrix is already non-uniformed and digging it will change its non-uniformity to something different altering metal detectors response. So even under these conditions the act of digging the target can give the impression of having disturbed a "halo" when in fact there was none.

There is no question that metallic iron, as it rusts in the ground, can cause a "halo" of spinel (gamma) iron oxides which can alter the way the machine detects it either favorably or unfavorably depending on the response characteristics of the machine. This can be replicated in bench testing.

Copper does corrode in many soils often leaving a physical halo which is visible to the eye. However this halo is not (as some have supposed) of sufficient electrical conductivity that it might have an impact on detection; and the lower electrochemical activity of copper with respect to iron makes it unlikely that copper corrosion has much impact on nearby iron mineralogy.
Metallic particles are not transferred to the surrounding soil in metallic form other than the obvious, that remnants of a disintegrating metal object may be moved by bioturbation, vertisol churning, freeze-thaw, gravity driven slope creep, and the soil movement mechanisms. The result is of coarse far less detectable than the original metal object.
One can take samples of these metallic element containing compounds, and in isolation verify that their electromagnetic characteristics are different from other compounds. However other than in the case of iron being altered to maghemite or rarely lepicocrocite (which have high magnetic susceptibility), the properties of the altered metal compounds are too weak to be detected in situ by a metal detector because of their small mass and their distance, relative to the soil bulk and its electrical and magnetic properties.
I have never seen a credible physical science based explanation for detectable “halo” around a corroded copper coin. And when it comes to dirt, I know quite a bit. But….there are things that dirt knows that I don’t.
--Dave J.

------------------------------------------------------------------------------------




Carl Moreland Chief Engineer from Whites ha ts also said thehalo theory is fiction.

Mike

[woodstock]

So what can you say about a coin left in the ground undisturbed? Your claim to fame is the the matrix and that there isn't "enough" conductivity for it to be detected or create a "halo" just because it can't be detected. But you really have nothing to back it up if the coin is there "in the matrix" and undisturbed.
Yes, the halo is there but only until the coin is dug like an antenna or sorts. If you can't find what isn't there after the dig doesn't mean it doesn't exist. Only that you and everyone has no explanation for it's effect, just a fancy explanation why it shouldn't exist. Call it undetermined variables, just like disturbing the matrix, but the undetermined variable is what we call a halo. If you look at it this way then why can't you accept it? We are supposed to accept your reasons, right ?
We can discuss this for the rest of our lives and until you can give me a real and factual reason or reasons with proof that it's not there I and many of us will continue to believe that it's there.
Heck, the mineralization caused by years of a dog peeing near a tree can cause a false signal according to experts but those same experts want us to believe that a halo can't form around a coin ? Then I suggest you think again.
Yes, many things you've stated are indeed a fact but you failed to offer an explanation why a coin buried for 125 years can be found at 10" when another coin in the same ground buried at the same depth for 50 years can't. You can be a scholar on dirt with all the thick words that make you a total dirt expert but in the end until you can prove that a buried and undisturbed coin doesn't have a "halo" then those words will remain empty. That's because you can't prove this because you'll have to disturb the soils "matrix" when you dig the coin. You believe what you feel is right and I will do the same. But on this topic we are on different sides of the fence and will remain that way. I need proof and words are not, what I've been believing in and digging for 29 years is. IMHO, Woodstock

Originally Posted by Mike Scott

Happy New Year all!


Here is some of that David Johnson information;

-----------------------------------------------------------------------------------

The digging of any target out of its matrix can disturb the 'lay of the land' and therefore the response of the metal detector. This can give someone an impression there was a "halo" that was disturbed when in most cases it was the uniformity of the matrix that was disturbed by the digging.
In rocky or already disturbed soil, the matrix is already non-uniformed and digging it will change its non-uniformity to something different altering metal detectors response. So even under these conditions the act of digging the target can give the impression of having disturbed a "halo" when in fact there was none.

There is no question that metallic iron, as it rusts in the ground, can cause a "halo" of spinel (gamma) iron oxides which can alter the way the machine detects it either favorably or unfavorably depending on the response characteristics of the machine. This can be replicated in bench testing.

Copper does corrode in many soils often leaving a physical halo which is visible to the eye. However this halo is not (as some have supposed) of sufficient electrical conductivity that it might have an impact on detection; and the lower electrochemical activity of copper with respect to iron makes it unlikely that copper corrosion has much impact on nearby iron mineralogy.
Metallic particles are not transferred to the surrounding soil in metallic form other than the obvious, that remnants of a disintegrating metal object may be moved by bioturbation, vertisol churning, freeze-thaw, gravity driven slope creep, and the soil movement mechanisms. The result is of coarse far less detectable than the original metal object.
One can take samples of these metallic element containing compounds, and in isolation verify that their electromagnetic characteristics are different from other compounds. However other than in the case of iron being altered to maghemite or rarely lepicocrocite (which have high magnetic susceptibility), the properties of the altered metal compounds are too weak to be detected in situ by a metal detector because of their small mass and their distance, relative to the soil bulk and its electrical and magnetic properties.
I have never seen a credible physical science based explanation for detectable “halo” around a corroded copper coin. And when it comes to dirt, I know quite a bit. But….there are things that dirt knows that I don’t.
--Dave J.

------------------------------------------------------------------------------------




Carl Moreland Chief Engineer from Whites ha ts also said thehalo theory is fiction.

Mike

[woodstock]

Ok, I apologize for the mix up. It sounded to me that you we saying the coin would disappear when only the "halo" does. HH, Woodstock

Originally Posted by Jason in Enid

I think you need to re-read what I posted. I never said a halo blocked the signal. I said the same thing you posted.

[woodstock]

This is what I misread but it does sound like you did say the coin disappears...right? The coin would still be detected, but wouldn't sound off as big (or well) without the halo. IMHO, Woodstock

Originally Posted by Jason in Enid

Soooo, according to YOU (respectfully), it is impossible for a coin to leach metals into the surround soils (respectfully) creating a larger "footprint", but disturbing the soil can make it impossible to see the same coin (respectfully). What a joke (respectfully).

[Mike Scott]

Originally Posted by woodstock

Man are you wrong on this subject. I've been detecting for over 28 years and the HALO effect that you say is a myth is real. If you want to come over to my place and run your detector in my large (and dated) test garden you'll see. I have 3 different rolls of various coins and scrap buried from 4 - 8- 12 years (or as long as I've been living where I live) and they are all buried a 8 inches in hard packed (hammered) soil so there is little depth change from age. I have faint signals on all the 4 year coins, better on the better on the 8 and even more solid on the 12. If the Halo effect was an urban legend then explain this and your proof that it is because I have the proof in my back yard. And when the ground is wet, all signals are stronger.
All metals will degrade into the soil, like the green you'll find on a IH penny. That green on the penny from years of being buried has created a larger halo around the penny. I've dug IH penny's at 10" in the old days that hit harder than lincolns at 6". And silver does this too.
Most expect that a halo should still be there after the coin was removed and because it's not they say like you that it doesn't exist. But they don't realize that once the coin is gone and the dirt displaced the halo is displaced as well.
So say what you want but when you do explain to all of us why your right. And then explain why a 125 year old coin buried at 10" will sound off better that a 50 year old coin at a shallower depth ? When you can convince me with your explanation why they don't exist then I'll believe you. And then my test garden and many others gardens mean nothing. IMHO, Woodstock

Your results on 4, 8 and 12 year old buried targets may be true but it is from the dirt and the matrix of the soil being disturbed and most likely due to the ground phases and anomaly of disturbed soils slowly creeping closer over a few years- not a halo being created….If a halo was created to that extent targets thousands of years old could be found 10 feet deep!
It doesn’t matter so much if the ground is hammered, watered or blessed by a priest- it is still disturbed soil and different from the soil around it unless it was put back in the hole EXACTLY the same way (which is impossible) or the garden was made in a completely tilled area making it uniform. Known prehistoric burials thousands of years old still retain different ground phase from the surrounding natural or undisturbed soils. Burials hundreds of years old also have different ground phase values which are more noticeable than the prehistoric ones.

If the halo existed Copper Culture artifacts from the Great Lakes region that have lain in undisturbed ground (some as long as 8000 years) would have HUGE halos and be able to be detected much easier and at much greater depths…….that is not the case. I have recovered hundreds of these artifacts and none have exhibited any kind of expounded depth that could be attributed to a ‘halo’---same with coins and relics I have recovered……. I have dug and documented Copper Culture targets in-situ many at depths that barley beep- even on the deepest units and then compared to air tests and set them up in test gardens.

JMHO(and the opinion of many of the mfg detector designers)

Mike

[woodstock]

I'd say that's because lead is softer and corrodes to white. That white would be lead mineralization and the bullets halo around it. I've always dug lead and lead has always hit harder than other metals . IMHO, Woodstock

Originally Posted by Lightningjack

Does lead leave a halo, the only reason I'm asking is because I've dug CW bullets way deeper then any coin & there almost always a solid tone with good VDI's... Just curious if the halo is why lead reads so much better in the ground then other metals... Thanks...

[Toomacho]

[Rudy]

Originally Posted by Jason in Enid

Soooo, according to YOU (respectfully), it is impossible for a coin to leach metals into the surround soils (respectfully) creating a larger "footprint", but disturbing the soil can make it impossible to see the same coin (respectfully). What a joke (respectfully).

I don't think that metal leaching off a coin and forming a "halo" (a volume around the coin, which contains some of the metal salts and oxides of the leached metal) is in question, we've all seen the stains. The real question is wether the halo is detectable by the detector, or if there is some other mechanism that is responsible for the increased detectability of the coin.

I am also of the opinion that the undisturbed ground matrix is the primary condition for increased detectability. I'll offer a couple of reasons why I believe that.

1.- When you pin point this long buried target in all-metal non-motion mode, why does the target largely pin point as a coin sized target, rather than the large blob one would expect if it was the halo that caused the detection?

2.- If these small, diffused particles that make up the halo are what is being detected then why are small gold chains so darn difficult to detect? After all, the small gold links have better conductance than the diffused halo particles and therefore generate larger fields in response to the Eddy currents induced by the transmit field from the coil.

[woodstock]

Yea Mike I agree that there are many thousands of metal items of buried for thousands of years, but these would be mineral veins and not left by man. And many of us have dug half way to China only to give up on the target. This can explained by " Target Falseing " or the object to deep to dig. The target can only be found if the signal can reach it. So saying that objects buried 10 feet deep should be found because of the halo you claim doesn't exist holds no bearing on if the halo is there or not. And digging up copper artifacts and re burying them in a test garden and trying to detect them then hasn't disproved anything, leave them there for ten years and then write your findings. And I'm aware on signatures left by many things that were buried, even graves. Again, even with todays best units there only capable of a somewhat shallow depth, not feet like you'd like to suggest a halo would create after being buried for eons, and therefore would not be found. IMHO, Woodstock

Originally Posted by Mike Scott

Your results on 4, 8 and 12 year old buried targets may be true but it is from the dirt and the matrix of the soil being disturbed and most likely due to the ground phases and anomaly of disturbed soils slowly creeping closer over a few years- not a halo being created….If a halo was created to that extent targets thousands of years old could be found 10 feet deep!
It doesn’t matter so much if the ground is hammered, watered or blessed by a priest- it is still disturbed soil and different from the soil around it unless it was put back in the hole EXACTLY the same way (which is impossible) or the garden was made in a completely tilled area making it uniform. Known prehistoric burials thousands of years old still retain different ground phase from the surrounding natural or undisturbed soils. Burials hundreds of years old also have different ground phase values which are more noticeable than the prehistoric ones.

If the halo existed Copper Culture artifacts from the Great Lakes region that have lain in undisturbed ground (some as long as 8000 years) would have HUGE halos and be able to be detected much easier and at much greater depths…….that is not the case. I have recovered hundreds of these artifacts and none have exhibited any kind of expounded depth that could be attributed to a ‘halo’---same with coins and relics I have recovered……. I have dug and documented Copper Culture targets in-situ many at depths that barley beep- even on the deepest units and then compared to air tests and set them up in test gardens.

JMHO(and the opinion of many of the mfg detector designers)

Mike

[Mike Scott]

Originally Posted by woodstock

So what can you say about a coin left in the ground undisturbed? Your claim to fame is the the matrix and that there isn't "enough" conductivity for it to be detected or create a "halo" just because it can't be detected. But you really have nothing to back it up if the coin is there "in the matrix" and undisturbed.
Yes, the halo is there but only until the coin is dug like an antenna or sorts. If you can't find what isn't there after the dig doesn't mean it doesn't exist. Only that you and everyone has no explanation for it's effect, just a fancy explanation why it shouldn't exist. Call it undetermined variables, just like disturbing the matrix, but the undetermined variable is what we call a halo. If you look at it this way then why can't you accept it? We are supposed to accept your reasons, right ?
We can discuss this for the rest of our lives and until you can give me a real and factual reason or reasons with proof that it's not there I and many of us will continue to believe that it's there.
Heck, the mineralization caused by years of a dog peeing near a tree can cause a false signal according to experts but those same experts want us to believe that a halo can't form around a coin ? Then I suggest you think again.
Yes, many things you've stated are indeed a fact but you failed to offer an explanation why a coin buried for 125 years can be found at 10" when another coin in the same ground buried at the same depth for 50 years can't. You can be a scholar on dirt with all the thick words that make you a total dirt expert but in the end until you can prove that a buried and undisturbed coin doesn't have a "halo" then those words will remain empty. That's because you can't prove this because you'll have to disturb the soils "matrix" when you dig the coin. You believe what you feel is right and I will do the same. But on this topic we are on different sides of the fence and will remain that way. I need proof and words are not, what I've been believing in and digging for 29 years is. IMHO, Woodstock

Its not my claim to fame-just posting what I have read and observed over many years detecting, experimenting and working inside the detecting industry for most of the major manufacturers and their engineers

It doesn’t matter to me if you believe in the halo theory or not-it’s a theory that many dispel as a myth.
I will continue to believe what the experts in the industry regarding metal detectors, targets, signal analisys and dirt say.
ESPECIALLY when my results and testing in real life, in the air, on freshly buried targets, IH pennies and thousand year old copper artifacts in my and other professional test gardens, enforces.

I am not trying to make anyone look bad, just pass along information and facts I have learned, I always try and be open to new concepts and theories even if they go agianst what I have been taught or though was fact for years-most of the civilized world thought the world was flat a few centuries ago.......

HH

Respectfully,

Mike