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Here are my lengthy replies to good-target Iron Masking.

September 18, 2020 12:06PM avatar
There's a bunch of stuff already out there on the forums and in videos. But I would like to know what you all think about it.

Do you avoid really junky areas or welcome the challenge?
While I would much rather hunt a virgin site and avid the 'junky' areas, that is exactly what I used to do ... back in the early days of detecting, but that was because almost any site I visited WAS a virgin area, ... at first. You simply hunted all the area you could and recovered all the good-sounding targets you could, and it was kind of easy to avoid the areas that had an increased amount of junk. But most of that was when we had BFO's and conventional TR's and before we had Discrimination which meant I was finding some of the coins and other desired small artifacts in and around Iron Nails quite easily. Then, as detector designs 'improved', we had models with variable Discrimination and that made many of them not work well at finding smaller-size non-ferrous targets in a ferrous-littered environment.

Then, as more people got into the hobby, some of those trashier sites were hunted periodically by others, but they, too, were 'cherry picking' ... sometimes intentionally and sometimes they just didn't know it. By that I mean, they were using a Discriminating detector that had too much lower-end rejection and even with a bold Bottle Cap reject setting and using a smaller-size coil, they couldn't get a good signal on a Penny in a close Iron Nail situation ... such as my Nail Board Performance Test layout. Plus most of them were using a standard 8" coil or larger, and that didn't help.

Then many were using the earlier motion-based VLF-Disc. models and, with their very fast sweep-speed requirement starting about '78, they couldn't handle the terrain and brush in some older sites, nor handle the heavy amount of trash, be it ferrous or non-ferrous (although I think you're referring specifically to 'iron masking' in this post).

Finally, along came '83 and the introduction of visual Target ID, and what we saw were a lot of disgruntled hobbyists because in all the very dense Iron trash environments, they were trying to rely on a good-target 'Lock-On' and very seldom was that going to happen. Especially when some used too much Discrimination AND most of those TID detectors were also the very fast-sweep circuitry design.

Back to your question, and to qualify my answer, I am referring to locations that were or are no-longer a virgin site. I had thinned down some of the easier pickings, and others who came along sometimes found a coin or two, but usually they didn't last too long. A 30 minute to 1 hour hunt and they'd pack up and leave.

Thus, for the first dozen years or so, when I was hunting some ghost towns and similar old-us sites, I was using the earlier detector models that worked in the ferrous junk reasonably well. I avoided the fast-motion detectors and relied on my better VLF/TR-Disc. and straight TR's to handle the conditions. It was also apparent that in many older locations, the frequency of coin loss and recovery was closely associated with the more used, and now trashy, parts of the sites, so it was in my best interest to 'hunt in the trash.'

Another fortunate thing in 1983 was the introduction of the Tesoro Inca in July, giving us our first really decent slow-motion detector with quick-response and fast-recovery that also handled Iron Nails and other ferrous debris better. That made a very big change in my approach to where I hunted when taking on a lot of those older sites. I continued to use the same proven search method or technique of using a smaller-size coil as well as working a location slowly-and-methodically. But then it was much more pleasant because those new detectors were also silent-search which was kinder on the hearing because the earlier TR detectors had to maintain a uniform coil-to-ground relationship and that called for hearing subtle increases and decreases in the adjusted audio Threshold hum, and frequent re-tuning.

At that point I would still hunt the 'fringe' areas of old town sites, stage stops, dance halls and other old-use locations, but I enjoyed heading for the more commonly-used areas which, as I had learned through the years, often had a lot more Iron Nails and other dense debris to deal with. Then, armed with a better detector at the time, and keeping a smaller-size 7" Concentric coil mounted and hunting slowly-and-methodically, I did my best to thin out as many coins and small non-ferrous artifacts as I could. that were partially masked in the Iron debris .... but often totally masked to those using the wrong coil, the wrong detector and/or the wrong search techniques.

That good habit of looking for trashier areas at old sites, then grabbing a good detector & coil for the task, has continued to this very day.

How bad is iron/target masking really?
Good-target masking caused by nearby Iron trashcan be very bad. Naturally, a lot will depend on the size, shape and orientation of one ferrous object located close to a non-ferrous target. Another factor is their 'depth' or distance from a search coil, and which of the two is closer to the coil's Electro-Magnetic Field. And we can't ignore the fact that there is almost always going to be more dropped or discarded Iron trash objects in an area than there will be lost coins. Thus, a lost coin is often out-numbered by the amount of Iron, so there's a greater likelihood that some of that Iron trash will be close enough to partially mask a coin.

As we can imagine, Iron target-masking is certainly something we should be aware of and plan on being able to take on that challenge. Thus, it now gets down to the individual to select the best detector performance, best settings to use, best coil to work in and around the debris, and then use the best sweep technique to unmask some of the hidden keepers.

What type or detector do you prefer in these areas-Beep and Dig or target ID?
Both 'types' although the first is more of a 'technique' but the term has been used for a few decades now to group detectors that lack a visual Target ID display.

Going back to the early conventional Metal / Mineral Locator days with a TR, for example, you would adjust the Metal / Mineral tuner to establish a working Threshold audio hum by Tuning in the Metal direction. Then you would hear that slight audio hum as you searched and, if you encountered any Ferrous or Iron-based target, such as an Iron Nail, the detector would null-out and the 'hum would disappear until you swept past the target. If you swept the coil over a non-ferrous object, such as a coin, trade token, silver or gold ring, etc., you would hear an audible increase from that Threshold-level 'hum.' So rather than a nulling response from Iron, you heard a good-sounding 'Beep!' from the increased audio from a coin. You heard the Beep! So it was then time to 'Dig' to recover the non-ferrous target.

Therefore, those who used the BFO's and TR's and TR-Disc. models ... just like those using our modern-day VLF-Disc. now just referred to as motion-based Discrimination ... would search and ignore what they don't hear because it is rejected, but they can recover any potentially good target if they hear a 'Beep' response. Thus, the 'technique' of listening and making a did / no-dig decision based simply on the audio response is using a 'Beep-DIG!' 'technique'.

From '83 to the present we have seen most manufacturers produce models that feature some type of visual Target ID display. They might have a needle or an LCD type scale with individual segments for TID, or they might use a numeric Visual Discrimination Indication read-out, or VDI number, to help classify or identify a located target. During that span one manufacturer, Tesoro, mainly produced models that were non-display designs, and it became a popular trend to classify that non-display model as being a 'Beep & Dig' design. But in reality, it is simply using an audible search technique, and that's exactly what I do.

Today Tesoro is gone, but DeepTech is still producing very good working models that also lack a TID or VDI display and you simply rely on the audio performance. Or be one of the many, many avid hobbyists like me who enjoy having one, two or more good Tesoro's to take afield.

Back to your question of what 'type' detector I like to use, it is one that can meet the following requirements:

• Be light-weight, comfortable, have functional controls. Those that are useful and have a good adjustment range.
• Have a Disc. adjustment range to accept Iron nails ... if possible ... with audio Tone ID.
• Have a smaller-size search coil that handled iron well.
• And the kicker requirement is: Be able to pass my NBPT and produce at least 7 or 8 out-of 8 hits.

As for having a visual TID or VDI display, or both like some have? No, it isn't a requirement because with the very closely oriented Iron junk, the audio based on conductivity of the close good target will be a blended audio tone response and visual ID response making it, basically, useless. On occasion I might glance at the visual display to see what the behavior is, such as a lock-on or a randomly jumpy read-out, but when hunting in Iron junk I rely on the Audio and use a Beep-DIG approach to success.

How important is coil size?
Search coil size and search coil type are very important. The coil size and design are only part of the answer, however, because some detectors they are attached to do not have a good circuitry to handle a dense Iron Nail contaminated site. They do not process a rejected signal and recover quick enough to process an near-by non-ferrous target. So you can't only compare coils unless you also compare detector.

For example, my preference is to use a smaller-size search coil that works efficiently in and around Iron debris on a preferred detector. A 'smaller-size" search coil, to me, is usually a round shape, or nearly so, and measures 4½" to 6½" in diameter. There can be an unlimited number of scenarios we might find a coin and multiple Iron Nails positioned in, so I rely on a few test Scenarios I have encounter afield with one or more Iron Nails. Mainly, as you might imagine, I use my NBPT to qualify a detector and / or search coil for such a task.

Because I spend the bulk of my detecting time hunting in older places with a lot of Iron Nails, building rubble, and dense brush and other vegetation, or I hunt in urban settings were I am encountering a lot of bottle caps or pull-tabs, etc., I keep smaller-size search coils on most of my detectors .... and they serve me well. But here is an example where search coil size means very little when it comes to performance at unmasking a desired old coin. Let's take a 5" DD, 6" Concentric, 6½" Concentric, 5X9½ DD and 6X11 DD coils.

Which of these wouild be the best coil to use in the nastiest of Iron Nils environments? For ME and using MY detectors, it would be a 5" DD that I keep mounted on my Nokta FORS Relic, or the 4.7X5.2 DD 'OOR' coil on my FORS CoRe. It might be a 6" Concentric coil like I have mounted on my Tesoro Bandido II µMAX or Silver Sabre µMAX. All four of these detectors and smaller coils easily give me 8-out-of-8 hits on the NB.

I can use my Nokta / Makro Simplex + w/5X9½ DD and get 6 or 7 out-of 8, and get at least 6 with the 6X11 DD on my Garrett Apex.

I have used a 6" DD on a MInelab Equinox 800, or the 5X8 DD on my Minelab Vanquish 540 and they won't even get half of the potential hits. And I have a Fisher / Teknetics 5" DD in my Accessory Coil Tote that can work on a Fisher F44 or a Teknetics Omega 8000 and provide very good Coin Hunting performance in modern trash. But even with the little 5" DD coil, they are absolutely terrible when you try to work the NB. And I mean terrible performance.

Therefore, to your question, search coil size and type are very important, but having a good functioning detector for handling Iron is also a mandatory ingredient.

Do you use iron audio if your machine has it?
I guess we need to clarify just what "Iron Audio" really is. Basically, it is the ability to hear Iron or Ferrous targets.

NO, my two Tesoro models do not provide any Iron Audio for most ferrous junk because at their minimum Discrimination setting (using Tesoro's ED-120 circuitry) they are rejecting most ferrous targets.

YES, with my regular-use settings with my Nokta FORS CoRe, FORS Relic and Simplex +, with my Minelab Vanquish 540, with my White's XLT and MX-7 and with my Garrett Apex because they provide a broad-range of Discrimination that allows me to set the Discrimination low enough to hear ALL ferrous-based targets, or at least low-enough to hear most Iron Nails. Therefore I DO hear an Iron target Audio with all of them. Additionally, some can be set to hear just one single tone for all targets, ferrous and non-ferrous, but most of them have an Audio Tone ID feature that assigns what is referred to as a Low-Tone or Iron Audio.

Now there is one more feature, let's call it a special feature, that is called Bottle Cap Reject on the White's XLT or called 'Iron Audio' on the Garrett Apex. Just accepting or hearing the Iron means you have an Iron Audio response, but on these models you have their added features. With the XLT, the BCR function helps to audibly classify possible Bottle Caps (the old crown cap designs we pried off) with a very broken-up audio response.

With the Garrett Apex 'Iron Audio' function, it only works when you are using some amount of Discrimination to reject the Iron targets, so you wouldn't normally hear it, but use the 'Iron Audio' function if you have a suspicious target. Like a very jumpy VDI caused by a Bottle Cap or maybe a piece of rusty tin. Then the Iron Audio function will give you a low-tone Iron Audio response as you approach and depart the sweep over a suspicious target.

To be specific, Yes, I like to at least listen for Iron Nails on most models that allow me to, then I can rely on the Low Iron Audio Tone to alert me to an Iron object and I can work the coil around it to try and isolate a possible non-ferrous target that is partially masked.

Do you like a detector that blends the audio or just gives a solid individual beep on close targets?
If you are using a 1-Tone detector, then you can't hear the results of a blended audio caused by two different objects with different conductivities being too close or touching which is going to create a 'blended' audio and visual read-out. My Tesoro's hunt that way as they are a single-tone design, an I like them.

All my other detectors produce a multi-tone audio. Some a 2-Tone, some a 3-Tone, one of them a 4-Tone, and two I use have a 5-Tone audio response. The MX-7 offers 8 and 20 Tone, but I never use that many. With all of these models, you can get a single, separate 'Beep' from an individual target IF it is not too close or touching another metal target. If there are two or more targets that are too close together and having a joint effect on the EMF, you are going to have a 'blended' audio and visual response.

One way to help eliminate some of the 'blended audio' is to use a smaller-size search coil and hope to encounter an individual target so as not to have the signal influenced by a nearby target. A larger-size coil is going to result in more 'blended' target responses.

How important is target ID with target/iron masking?
Not very important as it won't is won't isolate a good target from a masking target well if they are too close, and that's what is causing the masking in the first place. If a good target is partially masked, you'll be relying on the audio response. Target ID then is only going to work once you have recovered the good target and take a look at it.

How important is audio with target/iron masking?
Audio ... The #1 feature you need for finding anything good close to anything bad. If you don't have audio, you wouldn't know a good target was there.

If you could only have one metal detector for these types of sites what would it be and what coil would you use?
\For the very tough, very dense Iron Nails and other ferrous and non-ferrous junk I typically encounter in the ghost towns, homesteads, stage stops, pioneer and military encampments and similar old sites I like to hunt, and from my very reliable and very proven current Detector Outfit, they would be in the following order:

Nokta FORS Relic w/5" DD
Nokta FORS CoRe w/'OOR' DD
Tesoro Bandido II µMAX w/6" Concentric coil
White's MX-7 w/6½" Concentric coil

NOTE: The next two would be the Nokta / Makro Simplex + w/5X9½ DD and Garrett Apex w/6X11 DD, but once there is a smaller-size search coil for either of those models, and based on how well they currently perform with those larger size coils, I suspect they will move on up the list of a very good model to grab for hunting such challenging places.

I know that's a lot to answer, go over it in your minds and take some time to answer each question if you can. I've got my own ideas and have really been putting all my metal detectors through different challenges the last few weeks. I'll give my opinion and may even do some video later. You might be surprised at what I pick.

I like surprises.smiling smiley


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Metal Detector Evaluations and Product Reviews
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Edited 1 time(s). Last edit at 09/22/2020 01:11AM by Monte.
Subject Author Views Posted

Let's discuss target/iron masking

diggindeep 231 September 17, 2020 10:16AM

Re: Let's discuss target/iron masking

UtahRich 128 September 22, 2020 11:37PM

Re: Let's discuss target/iron masking Attachments

EL NINO 138 September 22, 2020 04:46PM

Re: Let's discuss target/iron masking

Dan'o 131 September 21, 2020 08:25PM

Re: Let's discuss target/iron masking

diggindeep 140 September 21, 2020 04:52PM

Andrew, back to the "Iron Masking" discussion and your new video.

Monte 153 September 22, 2020 03:34AM

Re: Andrew, back to the "Iron Masking" discussion and your new video.

D&P-OR 133 September 22, 2020 11:17AM

Re: Andrew, back to the "Iron Masking" discussion and your new video.

diggindeep 134 September 22, 2020 10:05AM

I'd like to see a 5" or 6" small coil for ....

Monte 137 September 22, 2020 12:46PM

Re: I'd like to see a 5" or 6" small coil for ....

D&P-OR 143 September 22, 2020 01:13PM

Re: Let's discuss target/iron masking

D&P-OR 137 September 21, 2020 06:04PM

Re: Let's discuss target/iron masking

diggindeep 136 September 21, 2020 07:10PM

Re: Let's discuss target/iron masking

D&P-OR 122 September 22, 2020 10:46AM

Re: Let's discuss target/iron masking

D&P-OR 126 September 21, 2020 07:12PM

Here are my lengthy replies to good-target Iron Masking.

Monte 179 September 18, 2020 12:06PM

Re: Here are my lengthy replies to good-target Iron Masking.

diggindeep 139 September 18, 2020 10:14PM

Re: Let's discuss target/iron masking

D&P-OR 152 September 17, 2020 07:55PM

Re: Let's discuss target/iron masking

D&P-OR 151 September 17, 2020 10:40AM

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