Sunday, November 14, 2004

Chapter 4: The Wrong Way to Use the IRON MASK Mode (Update 8-03-2005)

As we tweak our explorers even more, let us address something that is possibly taking depth away from us.

IRON MASK is a very useful tool. However, there is a tendency for people to abuse it thinking that they are solving one problem but actually creating another.

The problem I am talking about is the tendency for people to eliminate the drumming (in FERROUS, pinging in CONDUCT) of signals that I have previously discussed by mixing in IRON MASK discrimination.

Unless somebody turned over a bucket of nails at the site your hunting, that constant drumming in your ears is actually soil mineralization and you are hunting way too HOT on the sensitivity. Users of the Explorer have a tendency to hunt with sensitivity too high as this amazing machine can still deliver despite the HOT settings.

The Explorer is an automatic ground balancing metal detector. Set the sensitivity too high and the ground balancing software stops discriminating some of the soil mineralization and starts identifying them as targets. Soil mineralization being iron oxides and such, it will sound off as low tones in FERROUS and high tones in CONDUCT. These are commonly called false signals or falsing. At this juncture, some users mix in IRON MASK slowly to discriminate out the signals coming in from soil mineralization. It will work but you are loosing on two fronts here:

First, you are not hearing the nulls and the falsing anymore and are therefore not able to properly set your sensitivity for maximum depth and smoothness of operation. Take note that HOT sensitivity settings can cause greater target averaging effects which makes it more likely that a deep target will land in a different place on the SMART FIND screen or give off altered DIGITAL ID readings which can land it in the iron masked area.

Second, you are discriminating the good with the bad. IRON MASK is similar to the old discrimination knob of detectors from yore with one major difference. It adjusts on the FERROUS scale instead of the CONDUCT. Why is this important? Because when that 12 inch deep 250 year old large cent is averaged and lands on the left side of the screen which IRON MASK has blacked out, that large cent wont be yours.

Furthermore, all discrimination reduces depth and using discrimination unnecessarily is a waste of your detector's most valuable resource.

Having a detector that provides so much information about its target makes a strong case for reducing or completely abandoning discrimination. All discrimination reduces depth by some measure. If you want every fraction of an inch that your detector is capable off, you must use the least amount of discrimination necessary.

In years gone by, discrimination's main purpose was to avoid digging junk. If the detector is able to let you know its junk, don’t dig it. The ability of the explorer to run in FERROUS tones makes this way of hunting even more viable as it allows you to avoid most of those pesky rusted nails that try to pass themselves off as silver under CONDUCT. The exception to the rule would be if somebody did turnover a bucket of nails on your site :)

I suspect that my opinions on IRON MASK will be a bit controversial. It is a fact that the Minelab Explorer will hunt effectively even with different settings and people will find great stuff using their own techniques. I qualify that the opinions stated here are my own. They were largely formed by reading books like “Taking a closer look at metal detector discrimination” by Robert C. Brocket and reading stuff on the net.

In summary, set the sensitivity right and don’t use IRON MASK as a crutch to create stability.

ADDENDUM: Pre-programmed discrimination patterns as well as LEARNED patterns can have the same effect as IRON MASK in blotting out signs of a hot SENS setting. I emphasize, it "CAN" but will not always do. It all depends what section of the DISC screen is blacked out.