Tom D's wisdom.

In an article "BENEATH THE MASK" on this very site, Tom Dankowski states:

"If a 8" coil can 'see' a one gallon volume of dirt and the 11" coil (not 10.5") can 'see' 7 gallons of dirt at any given time, it is a fact that you are 7 times more likely to 'mask' a object with the larger coil, especially in trashy areas. It is so easy to get into trouble with the larger coil AND NEVER KNOW IT!"

Brilliant for sure, but what about other factors? What happens when you crank up or drop the gain/sensitivity? What happens when you increase/decrease your sweep speed? How about proximity of the coil to the ground? What about the ground itself? What if it is highly mineralized or very little mineralization?(those were rhetorical questions) There are a monstrous amount of factors that can increase/reduce masking.

I recently have acquired a super sensitive Impact. It was constantly hitting low conductor targets, they were tiny, but the response was that of a high conductor at certain angles. I knew they were not good targets, I wasn't fooled, but i dug them anyway. That prompted me to think that. too much gain/sensitivity, can mask targets too. How many of us set the gain/sensitivity at high and never change it throughout the entire hunt?

He also states that:

"When you discriminate iron with any detector (Minelab calls it "iron mask") you have achieved nearly nothing. (Simply, there will be no audio response reported in the headphones). The detectors electromagnetic signal is still disrupted by the iron"

If you think about what this really means, it means that you can't ignore something without detecting it first, and if you detected it, then you can't ignore it. There really is no way to rid iron(besides digging it). All you can do is work around it.

Further in the article he states:

"Nine (9) coins were found with the CZ. Thirty-nine (39) ADDITIONAL coins were (unmasked) found with special equipment. Forty-eight (48) coins in total. Looking at the ratio a bit differently; 9 of the 48 coins were detectable by a top-line coin detector. Thirtynine additional coins--- that's over 500 percent MORE coins,,,, were masked! Yes, unsuspectingly, this is THE norm!"

When I first read this, I did a triple take. 500% more coins were masked? I didn't believe that. Who could? Well, I was wrong.

A local park was being redone and the dug down about a foot. After securing permission, I took my CTX 3030 and went to work. I found mostly clad and junk, nothing old. I used the standard and the large 17" coil. After a few days I thought it was cleaned out then the foreman came over and said "we are removing two more inches tomorrow". I thought "two inches? Big deal." I went else where the next day and drove by the park with an hour of so daylight left. I stopped and thought, "what the hell, lets just see". All of the sudden there were targets everywhere. Wheats, indians, V's, Buffs, a large cent, a crotal bell(no silver). All just two inches that the CTX couldn't see.

So 500% more? You bet your ass!

Thanks for reading



Edited 1 time(s). Last edit at 06/27/2017 03:20PM by Beyonder-Pa.

Amazing information. Thanks for the write up!

Thanks BP for revisiting and sharing some excellent info.

Like in Andy Sabitch books... too much gain is like high beam lights in fog...



Edited 1 time(s). Last edit at 06/28/2017 12:43PM by Shelton.

ummm; are you sure it's masking at play here?

Not disputing Tom's remarks or wisdom/knowledge at all, but not sure your park experience is relatable to his remarks regarding masking.

You say they dug down about a foot, and then you say they removed another 2 inches; so does that mean that when they dug down about a foot they removed that foot of dirt? That's what's implied.
If the implication is correct, it appears less a case of masking and more a case of reaching the depth at which the older coins lay. IOW, the older coins were "masked" by 12 to 14 inches of dirt between the previous surface of the ground and the depth at which they could be detected. Am I misunderstanding something here?

Wayne

Pleasant Garden, NC
AT Max, Nokta Impact, MX Sport, Nokta FORS Relic, GPX 4800, Infinium, Racer, Deus, F75SE, Nautilus DMC II (order of acquisition, last to first)

Does an archeologist argue with a plow? A bureaucrat with a bulldozer?

ncwayne Wrote:
-------------------------------------------------------
> ummm; are you sure it's masking at play here?
>
> Not disputing Tom's remarks or wisdom/knowledge at
> all, but not sure your park experience is relatabl
> e to his remarks regarding masking.
>
> You say they dug down about a foot, and then you s
> ay they removed another 2 inches; so does that mea
> n that when they dug down about a foot they remove
> d that foot of dirt? That's what's implied.
> If the implication is correct, it appears less a c
> ase of masking and more a case of reaching the dep
> th at which the older coins lay. IOW, the older co
> ins were "masked" by 12 to 14 inches of dirt betwe
> en the previous surface of the ground and the dept
> h at which they could be detected. Am I misunderst
> anding something here?
>
> Wayne

They removed 12 inches of dirt. So the CTX was about a foot blow ground level. So I was detecting in a pit a foot deep. Then they removed another two inches so I was about 14 inches below ground level. The CTX should of easily saw through those two inches. I know it was iron infested because I ran a few different programs including a two tone ferrous like where I could heqr the iron.

Hey Bey,
I don't think you're saying that all of the older coins were found at 2 inches deep, but that is the impression your wording gives.
I would expect it to be more likely that the removal of the additional two inches of dirt brought the older coins two inches closer to your coil, and that aided in their discovery.
So it's not a matter of the CTX seeing through 2 inches of dirt. It had to see through 2 inches of dirt PLUS the depth at which the coin lay beneath that 2 inches.
I'm not saying masking was not involved, but that the reduction in depth of the coins by removal of two additional inches of soil was a highly significant factor. Even more so, if there is any level of mineralization in the soil.
Were there masking targets (iron) removed in the first 12 inches? Of course. (Along with how many coins?)

I'd say there was much more unmasking done in the removal of the first 12 inches of dirt than in the subsequent removal of 2 additional inches. Yet, it was the removal of the latter 2 inches of dirt that revealed the old coins.
What would you say, Bey?

Wayne

Pleasant Garden, NC
AT Max, Nokta Impact, MX Sport, Nokta FORS Relic, GPX 4800, Infinium, Racer, Deus, F75SE, Nautilus DMC II (order of acquisition, last to first)

Does an archeologist argue with a plow? A bureaucrat with a bulldozer?

Not a technical hunter but I do know masking causes many good finds left in ground and feel many targets are just too deep for any detector to find.
Sure faster detectors have been made over the years but deeper ones I don't think so when 25 year old technology will go a foot.

"Hey Bey,
I don't think you're saying that all of the older coins were found at 2 inches deep, but that is the impression your wording gives."

The depth of the coins AFTER the removal of two more inches of dirt was less than an inch to a thin coating of dirt(practically on the surface).

"I would expect it to be more likely that the removal of the additional two inches of dirt brought the older coins two inches closer to your coil, and that aided in their discovery."

That would of been true if they were deep.

"So it's not a matter of the CTX seeing through 2 inches of dirt. It had to see through 2 inches of dirt PLUS the depth at which the coin lay beneath that 2 inches."

Yea I should of been clear about the actual depth of the coins AFTER the removal of the last two inches of dirt. The were practically surface finds.

"Even more so, if there is any level of mineralization in the soil."

Mineralzation is minimal in most areas of PA.

"Were there masking targets (iron) removed in the first 12 inches? Of course. (Along with how many coins?)"

The coins I was finding after the removal of 12 inches were all clad. Don't forget they were a lot of hunters their before me(I got there late). What they found I don't know. I was finding clad from the late 60's to early 80's I may have found a wheat or two during at that depth, but i'm not sure. They were large chunks of iron and iron nails as well as aluminum bits.

"I'd say there was much more unmasking done in the removal of the first 12 inches of dirt than in the subsequent removal of 2 additional inches. Yet, it was the removal of the latter 2 inches of dirt that revealed the old coins.
What would you say, Bey?"

Well yes and no. These old coins were at an estimated 14 inches deep. Maybe the Crotal bell and possibly the largie would have been DETECTABLE fringe targets. But there is no mistaken that there were layers of targets in that first 12 inches that were masking. It was the iron that was masking the last two inches after the first twelve which was why the older items were undetectable.

I surmised that this park was detected heavy back in the early 70's then filled with 6-8 inches of dirt around early 80's.

F75... CL mode... SENS=10

Amazing...