Detecting in Heavy Iron Part II – Defeating the Iron Monster

Detecting in Heavy Iron Part II – Defeating the Iron Monster

In part I, we talked about how important it is to hunt the iron, especially the nail beds, because often that is where the best items lie.   Now let’s build a pragmatic approach to hunt the iron and extract the finds from it.

General Techniques
In heavy iron, I generally come out swinging very slow but very smoothly.   I utilize minimal or zero discrimination.  I have my headphones on.   I detect about a three square foot section of the nail bed at a time.  I am hearing the iron, I am watching the display.   I take my time and scan and rescan the same areas at different angles.  What I am looking for is just a trace flash of a good number on the display.   What I am listening for is a faintest blip of a high tone between the low tones of the nails in my headphones.  Let’s look a little closer at each of these aspects:

Wear Headphones
I advocate wearing headphones (or headphone as I do with my Rattlers) in most any situation to pick up faint, deep signals.  Headphones are particularly critical in heavy iron, especially once you learn what to listen for.  Because of the noisy heavy iron, without headphones you are going to miss something you need to hear.

Bare-bones or No Discrimination
Perhaps it is possible to successfully hunt a nail bed thoroughly with discrimination with a detector that has awesome response time.  I want to hear the nails, though.  On my Fisher F75 I hunt all-metal with zero discrimination.  With the e-Trac, I find that just discriminating minimally reduces some false signals. Experiment yourself and check the forums for “ironclad” advice on your specific detector but when in doubt go all-metal.

Go Slow
Take your time.  If your speed is fairly slow and smooth, the nails grunt clearly in your ears.  Pay attention.  Be patient.

PRO TIP:  Imagine that the dirt is not there, and the nails and good targets are just suspended in place.  The nails outnumber the good targets 100 to 1.   Imagine that in order to hit a good target, you are having to fire a laser beam from the center of your coil between a tiny gap between many crisscrossed rusty nails.  Sometimes the gap is so tiny the laser barely gets through for a split second and touches the target.  Often you are only going to get the tiniest hint that this happened, so don’t miss it!  Insist that a good target lies in every square foot of the nail bed.  Don’t wait for them to clue you in;  work hard and slow at different angles until you hit them.

Swing Overlap
Your overlap between swings should be flat-out ridiculous.  I’m talking 80-90% to make sure the center of the coil passes directly over the tiny gaps in the nails between you and the desirable targets.  You don’t even have to step forward but once every five or more swings.  Forget the coil’s diameter and just detect with the very center of the coil.  If what you are doing seems like overkill you are doing great!

Audio
Again consult the forums for advice on setting up audio on your specific detector for hunting in iron.   I don’t do anything to the F75.   It sounds clean.  On the e-Trac, I set it to two tones – just a high and a low and adjust the pitch until it sounds the most comfortable in my headphones.  You want to make it as easy on yourself as possible.  You want all of the iron to sound the same, and sound comfortable to your ears so you can stand the noise.   Then coins and other non-iron objects will stand out against the sounds of the iron.

Sections
Dividing the nail bed into approximated three foot sections just makes you hunt more thoroughly.  I feel fairly sure that I am not going to get any more targets from the current section before moving to the next one.

Different Angles
I’ve found that sometimes I can only hit certain desirable objects in heavy iron at a single angle.    I would have missed the target completely if I had only tried a single angle, unless I got lucky.  Try hitting each section of a nail bed multiple times – each coming from a different direction.

Sensitivity
Most of the targets I am looking for in a nail bed are going to be 4-5 inches or less.   Anything deeper than that is just going to have too much interference from the iron.    I drop my sensitivity way down to like Auto to Auto-3 on the e-Trac, and about 60-75 on the F75.  Why?  Because although I want to “see through” the iron, I don’t want to see through good targets and hit the nails under them.

Reducing the sensitivity reduces the number of targets under my coil by eliminating the deeper ones.   This is why certain detectors  seem to “see through” iron at a certain sensitivity.  You are reducing the backdrop past the depth where most of your discernible good targets are going to be.  Find out what works best for you and your detector.  Experts on the forums can recommend optimum sensitivity and other settings for your detector to best “see through” iron.

IRON FALSING
Iron falsing is when a deep iron target fools the detector into thinking it is a non-iron target.  Some of the common iron objects that false regularly are severely bent nails, old nails with a rust “knot” in the middle of them, horse shoes, and any piece of iron with a big hole in it like a harness ring or a big flat washer.

Iron falsing wreaks havoc on metal detecting in general.    Along with pull tabs and deep 1965 quarters, falsing is one of the worst things about metal detecting.     In a nail bed, only some nails and other iron objects will provide false targets.

No doubt many detectors handle falsing better than others.   One of my favorite things about the MineLab e-Trac is it handles falsing excellently when configured correctly – way better than my Fisher F75.   With a 5″ coil, the e-Trac will do some severe damage in a nail bed.

Most detectors have  a quick switch from discrimination to all-metal to assist in checking to see if a target might be iron falsing.    This is great for general conditions, such as encountering a deep bent nail in open ground.   But this is why I prefer little or no discrimination in a nail bed.   I’m going to be able to predict it might be iron in the first place.

Dealing with Falsing in Heavy Iron
Check out the forums for tips on dealing with falsing for your specific detector.  With some experience, you will probably be able to “hear” falsing in your headphones and differentiate it from a good signal.

Experts generally agree that trying an iffy signal that you suspect might be falsing at different angles helps you differentiate falsing from a genuine “good” signal.   Turn and try to scan the target at 90 degrees from the direction you swung to obtain it in the first place.   Sometimes the falsing will only happen at a single angle, where a real desirable signal should sound the same at multiple angles.   This is great under general conditions,  but the technique is no good in a nail bed.  I’ve dug too many silver coins that I could just get a hint of at a single angle.  Also because of all the clustered iron, the item that is falsing at one angle may not false at the second, but a different piece of iron may false at the new angle.

In a nail bed, your are likely going to dig a few false targets if you are working hard to get the good targets.   At worst case, you’ve removed the falsing iron from the area, which increases your changes of hitting a good target that was lying nearby it.  I’ve dug things up out of nail beds like rusty old scissors, pocket knives and files that were the source of the falsing.  It’s good to get things like that out of the way anyway.

PRO TIP:  When in doubt, dig.  Often the only way to know for sure is to see for yourself.

Clearing Iron
You don’t need Confucius to tell you that getting the iron out of the ground will clean up the site and increase your chances of finding the good stuff.  But what and when should we move?

Move the Big Iron
I can’t tell you the number of times my detector has nulled out on a big piece of iron, I’ve dug the axe head or iron plate or whatever out-of-the-way and then find silver in its stead.


Even in a hunted out site, you’ll often find that previous detectorists have categorically hunted around big iron pieces – things like plow parts, wagon wheel rims, axe and other tool heads, cast iron stove parts.  If you are in a hunted out site, taking the time to move the heavy iron is how you are going to turn a skunk into a win.      Under the right circumstances, I’ll leave the detector in the truck and bring a shovel and a crowbar and do the work.  Get the big iron pieces out of the ground and get them out-of-the-way.  If I wear myself out, I’ll leave and come back to hunt well-rested the next day.

In a good site that is producing or a hunted out site that obviously produced in the past, it is worth taking the time to get that iron out of the ground.

Walk Softly but Carry a Big Magnet
My brother-in-law has one of those big super-magnets.  I think he bought it at Harbor Freight.   They are inexpensive.  It’s about half the size of a brick.   If I have a nail bed that I think still holds some stuff I can’t get to, I’ll borrow it and also bring a five gallon bucket.  I’ll pick a section of the nail bed that I have found something in and dig holes, stick the magnet in it and repeat.  The magnet gets about as big as a giant rusty bowling ball.   The chore is actually getting the nails off.     It takes about 3 hours to clear about 60-70% of nails from a 6 foot by 6 foot area and hunt it again.  It is hit and miss, but I have found some great stuff doing this.  I will only go through this trouble, however, if the site is a very good one that has produced some monster targets in the past.

Try a 5″ Search Coil
My SunRay X-5 small coil is incredible in heavy trash and nail beds.   It lets you get in between the nails and is a lifesaver.  If you hunt a lot of sites of long-gone structures, I’d strongly recommend finding a “Sniper” or other very small search coil for your detector.

Final Thoughts
As they say, nothing worth doing is easy.  It would be nice if we didn’t have iron or pull-tabs to deal with, but that’s the way it is.   Metal Detecting iron can be very aggravating, but with some work, it will eventually be no big deal.   Hunting in iron is just a special case of metal detecting that calls for specific techniques.

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Photo Credits
Flickr: Some rights reserved by jronaldlee

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There is 1 comment for this article
  1. OZARKS at 4:25 pm

    Another very helpful article. I have a site that is exactly along the lines of what you are talking about. It is literally a bed of nails! There is nothing but a very old foundation there now, partially reclaimed by the forest, but it is there. The entire “floor” is covered in nails. Nails from the walls, and nails from the roof!

    I rarely find anything good in that area, due to the nails, but, that may all change soon now that I have read your articles about places liek this. Since where I am hunting is an area that I can dig some, and then use a magnet, I may be able to find some goodies there. I know thay are there, it is just going to take more work than usual to sniff them out! Anything worth having is worth working for, so I think this area deserves a closer look!

    Anyway, thanks for the articles, I have some new knowledge and new ideas for an old iron infested spot!

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