Good read on target masking by Thomas Dankowski

[Tony N (Michigan)]

In March of the year 2000, Thomas Dankowski wrote this rather revealing article on masking of targets:

Thomas Dankowski's masking of targets

In it, he explains how something as simple as a staple above a coin in the ground can completely mask the coin from being detected. He's not talking about a staple
resting on the coin but several inches directly above the coin.
He goes on to explain what he did in his tests.
I'm curious if any detector to date has been made to unmask coins from metals directly above the coin.

 

[IDXMonster]

It would be a perfect situation in which that would happen. The rest we will never know about unless we are digging and sifting. So while it's interesting...we can't do much about it.

 

[Charles (Upstate NY)]

Point A he wasn't using a Minelab and point B he wasn't running all metal or at least allowing in iron. I have dug silver fused to rusty iron with Explorers (in all metal). So Tony the moral of the story, don't worry too much about rusty iron masking like that on Explorers and certainly not a staple. Another example, I have dug Barber half dollars in the same orientation of the staple story, rusted bottle cap at 4 inches directly centered over the Barber half dollar at 9 inches, multiple times.

This is an area where there are exceptions to the rule. Most often allowing in the iron (all metal or iron not discriminated out) will get hits on nearby/fused silver. But there are less frequent exceptions where discriminating out the iron gets a hit on silver, and when you switch to all metal the silver vanishes and its textbook iron. Maybe 9 out of 10 times all metal rules so I mostly play the odds but there are exceptions.

Sometimes when I'm working a particularly iffy signal I'll try both methods (all metal vs iron discriminated) which is when I first discovered the exception to my always running all metal rule. Rusty bottle caps is the opposite. I get more hits on good targets hiding under them with the bottle caps notched out vs all metal, odd. Explorers love to lock onto rusty bottle caps if they are allowed in, notch them out however and if silver is hiding under them it will pull the cursor above the notched out bottle cap area sometimes, that's your clue there may be a coin hiding under the bottle cap. It won't go all the way up into the silver zone where the coin belongs, but pulls the cursor higher than bottle caps go. But switch to all metal and the coin vanishes, the cursor jumps down towards the bottom right corner textbook rusty bottle caps.

^^^ more examples of why I never use the digital number mode, I would lose the oddball cursor behaviors that often tell me to dig/don't dig.

 

[Tony N (Michigan)]

Charles, when you say "all metal" do you mean absolutely no iron disc on the Explorer?
Is it possible to have a sliver of iron disc, maybe 1/8" wide on the left, and still get a good report on a non-ferrous target masked by bottle cap or iron nail?

How do you notch out an rusty bottle cap? do you put the detector in "Learn" mode? Or do you just go into Iron mask mode and move the disc on the left
of the screen up to where bottle cap appears?

 

[Charles (Upstate NY)]

Charles, when you say "all metal" do you mean absolutely no iron disc on the Explorer?
Is it possible to have a sliver of iron disc, maybe 1/8" wide on the left, and still get a good report on a non-ferrous target masked by bottle cap or iron nail?

How do you notch out an rusty bottle cap? do you put the detector in "Learn" mode? Or do you just go into Iron mask mode and move the disc on the left
of the screen up to where bottle cap appears?

That's right, a screen with nothing discriminated no black at all wide open all targets. Easily setup in the Iron Mask screen but I also have flavors of almost all metal screens saved for the Smartfind screen. For example a wide open all metal screen with just rusty bottle caps notched. That's not to say that I don't use discrimination, for example my heavy discrimination screens with just $1, $2.5, $5, and $10 gold coins opened up, plus silver.

Rusty bottle caps will textbook ID with the cursor bottom/right corner of the screen, with the cursor half off the right edge, and half off the bottom edge. But depending on how rusty and soil can creep up the right edge of the screen from that location about 3/8 of an inch. So I notch out an area about 1/8 inch wide by 3/8 inch tall starting at the bottom/right corner. About the only other targets I have seen hit in this area are buttons with rusty steel backs and the rare VERY corroded nickel.

As for your silver question there are nearly an infinite number of co-located target orientations in the ground. Depth difference between targets, depth of each target, size, coins, trash, and nails don't just lay flat they can be flat to completely on edge and every angle in-between. Then there is the particular coil you are using, smaller coils have much denser magnetic fields than larger coils. Its all about how many magnetic field lines intersect the target and induce a signal into the target. So a smaller coil with a denser field (more magnetic field lines) may induce a stronger signal into a target that is only peeking out from behind iron or trash, its possible. But then there is the shape of the magnetic field which varies with coil size and shape. I once hunted for 2 straight years using nothing but the 15 inch WOT coil. That coil's magnetic field was particularly good at hitting dimes partially on edge. The stock coil not so much. So at a given depth you have to think about how the magnetic field lines are angled, in this case with that big coil I think they were bending upwards at just the right angle at just the right depth to get a hit on dimes somewhat on edge that were not presenting enough target to smaller coils. You can go mad thinking about this stuff, is scary what's stuffed into my brain after years of using an Explorer LOL.

 

[IDXMonster]

Am I correct in saying the audio and numbers/smart screen are separate circuits? I SO wish the CTX had the EX2 audio. It can be somewhat similar but without Variability it just doesn't cut it. Not picking on my CTX...but they went backward in that deal.

 

[Charles (Upstate NY)]

Explorer audio is instantaneous, you can swing quickly back and forth over a target getting instantaneous audio target information without the cursor even moving or numbers updating. I typically give the target a few swings then stop my coil and then allow the numbers/smartfind screen to make a decision. I may repeat this several times from various angles on a difficult iffy target trying to establish an average of dig/don't dig decisions from the screen.

 

[Tony N (Michigan)]

Explorer audio is instantaneous, you can swing quickly back and forth over a target getting instantaneous audio target information without the cursor even moving or numbers updating. I typically give the target a few swings then stop my coil and then allow the numbers/smartfind screen to make a decision. I may repeat this several times from various angles on a difficult iffy target trying to establish an average of dig/don't dig decisions from the screen.

That happens to me quite often. I hear the tone but the screen lags or the numbers lag behind.

 

[Tony N (Michigan)]

Often I like to hunt in all metal with my explorer. But here where I live, on this property the detector is constantly drumming with all the nails in the ground.
It's enough to make a grown man cry. So I often just disc out some iron with a few slivers on the left of the screen. I don't know if this is hurting my chances.

With another detector of a competing brand, I opened it up to accept everything. What an eye opener. I was in a park and could hear the silver under the trash or near the trash target.
It would take quite a while to discipher the tones and not go at all by the meter because if I went by the meter, I wound never have dug them.

 

[Charles (Upstate NY)]

When I first started hunting in all metal allowing in the iron the iron low tones frequently gave me a headache. Now low iron tones are my threshold my brain doesn't really pay them any attention, but it took some getting used to.

 

[tiftaaft]

Tony, I have my Explorer set up similarly, I think my iron mask is at 30. I would be interested to know if this is hurting my chances for depth and masked targets as well... Charles is the guy with the answer... so I look forward to his response. It sure makes it a much more pleasant hunt without all those iron tones though..

 

[Charles (Upstate NY)]

It really depends on the site, how much iron there is, how wet the soil is, what size coil you are using, the orientation of targets near the iron, how bad its been pounded by detectors. There's nothing wrong with notching out iron and cherry picking a site the first go round. If its a good site but has stopped producing, well then allow the iron in and have another go at it. If that's not producing switch to a smaller coil and try again, or a larger one and only dig targets deeper than you were digging with the previous coils.

If you find a target with iron discriminated out DON'T waste the learning opportunity. This is one of those things where you have to prove it to yourself. STOP, before you dig switch to all metal and sweep the target again. Did it improve? Was it easier to pinpoint? Does the iron seem smaller now polluting a smaller area of ground without the iron null stretching the iron target out like a rubber band not wanting to let go of it?

One example where I would notch out iron is a cellar hole with a collapsed rotted to nothing building e.g. a layer of rusty nails is all that's left covering any good targets. I'll notch out iron and go slow with a small coil sure. There you can't really move your coil and not be on iron.

Those of you in northern climates where the ground freezes hard, after 1-2 bad winters with deep freezes hit your good sites again, the frost heave can flip coins that were on edge and undetectable over enough to get a hit on them. I have seen spots that we strip mined cough up many more coins after a couple bad winters. It moves the iron around also.

If you are a hard core hunter...here comes a DaveZ tactic...Dave would dig all the shallow trash out of a sight that was producing good stuff when it stopped producing.