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Deep Iron and Magnet?

Posted: Thu Jan 23, 2020 11:46 am
by Wigeon
I have a field of permanent pasture where I am plagued by deep iron. All the usual suspects that fool our detectors. ++=£

Yesterday I was down the best part of two spades deep but the complete, rusted iron, elongated harrow link still gave a mixed signal on the eTrac. The signal was broken to a degree so I was suspicious but still had to dig it.

I have been looking at small but strong magnets and wondering whether it would be practicable to use one in the hole to test for iron? I anticipate that it could be a problem near the detector etc. so care needed.

My line of thought is that, once down a spade depth of so and still more to go, hold the magnet in the bottom of the hole and see whether it is attracted. ??{((

Anyone tried it? If so, how did you get on?

Re: Deep Iron and Magnet?

Posted: Thu Jan 23, 2020 11:50 am
by Blackadder43
I think my issue would be the transporting in the fields of said strong magnet...
Against the electronics of the machine and headphones and mobile phones etc, im not sure i would want that on my person... :-/

Re: Deep Iron and Magnet?

Posted: Thu Jan 23, 2020 4:31 pm
by TinDigger
Even with a high grade neodymium you would still have to get within 2-3 inches to notice any attractive effects. By the time you have got that close you might as well just dig it anyway.

Re: Deep Iron and Magnet?

Posted: Thu Jan 23, 2020 4:58 pm
by sweepstick47
If such a magnet deemed the buried find to be ferrous iron what then? Would you leave it where it lies or consider you may be leaving a 7th Century Saxon weapon or other important ferrous artefact in situ? Best do what that little voice in your head tells you to do, check it out ::g Regards ss47

Re: Deep Iron and Magnet?

Posted: Thu Jan 23, 2020 5:36 pm
by Wigeon
sweepstick47 wrote:
Thu Jan 23, 2020 4:58 pm
If such a magnet deemed the buried find to be ferrous iron what then? Would you leave it where it lies or consider you may be leaving a 7th Century Saxon weapon or other important ferrous artefact in situ? Best do what that little voice in your head tells you to do, check it out ::g Regards ss47
I know exactly what you mean SS47. ::g
That little voice has a warped sense of humour though.
The number of times I have 'made my mind up' to walk on but been persuaded by him to dig are countless. So far, usually but not always junk. He's a treacherous little b**#&r ++=£

The eTrac is really a good discriminator but, as with all detectors, has its limits. It's tone usually gives a clue to the 'bad news' awaiting at the bottom of a deep hole though.

This field should be very good and in fairness I have had a medieval annular brooch and scabbard chape, so mustn't grumble too much :D Targets are all deep though and lots of junk. I suppose I am just thrashing around trying to avoid some of it.
Just for good measure, I got absolutely plastered in mud again too. 8-|

Re: Deep Iron and Magnet?

Posted: Sun Mar 29, 2020 5:35 pm
by mini dan
You could try gluing a small neodymium magnet onto a long thread and suspending it beside the hole. It may well swing to the hole slightly. I’ve seen this being demonstrated to show the strength of magnets by somebody selling magnetic bracelets. From quite a distance (about 2 metres) he was able to deviate the magnet on the string by moving a magnet in his hand. It may not work but possibly worth a try?

Re: Deep Iron and Magnet?

Posted: Sun Mar 29, 2020 6:57 pm
by PinkFloyd
If it’s still a mixed signal after 2 spade depths... it’s 100% iron ::g

Re: Deep Iron and Magnet?

Posted: Sun Mar 29, 2020 7:36 pm
by fred
PinkFloyd wrote:
Sun Mar 29, 2020 6:57 pm
If it’s still a mixed signal after 2 spade depths... it’s 100% iron ::g

How so? I would agree that on the balance of probability most very deep signals are likely to be junk but 20mm cases and other large bit of ordnance can also sound really dodgy if they are very deep. On beaches the signals don't always change as you dig, sometimes not until you actually move the target anyway. :D

Re: Deep Iron and Magnet?

Posted: Sun Mar 29, 2020 7:44 pm
by PinkFloyd
2 spade depths is going to be at least 12 inches, if it’s still iffy at 12 inches Fred.....it’s even 110% iron or part iron anyway .
:D