Why does trash read as silver?

[halgreene]

Hi,

I've been trying to dig a little less trash lately (newbie here, Fisher F5), so I've set the disc fairly high (65). But I still get solid hits in the 80's and 90's that turn out to be trash (pieces of rusty iron and can slaw, mostly). My question is: Why? What am I doing wrong? How am I misinterpreting the signal? (Or am I?) Is there a way to interpret the pinpoint signal to get a better read on what's down there before I dig?

Thanks,


Hal

 

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[SusanMN]

Rusty iron fools every machine I have owned. While it is in the ground my detectors act like it is something wonderful. Someone will come along with the scientific explanation, but you might as well turn your discrimination back down because you are always going to be dealing with it. You can, by raising your detector up, sometimes get a sense if the signal is something large, rather than small like a coin, which can help you decide to dig or not.

 

[airscapes]

For in-depth understanding read the following articles. I would suggest reading only half of the first one at one sitting, come back another day and finish it, go for a hunt, read it again.
Your will be very happy you did.
Truth About Search Coils

Halo Effect

As was suggested, allow iron to be heard, you will most likely find an iron target within the distance of your coil size someplace around the target.. i.e. target in the center there will be iron hit within a coils width/length of what you think is a the good target..

 

[Boatlode]

Dig everything. Discriminating detectors are notorious liars.

 

[Silver Searcher]

Use the force Luke.. and blank out your ID screen.

SS

 

[Manhunter]

Not an experienced metal detector, but do have a background in metallurgy. Keep in mind that iron and steel both have numerous other metals in them that are added during the refining process, so not sure if that may be giving false signals.

 

[luvsdux]

Haven't had the iron problem too much in my hunting, but flattened aluminum cans and other larger aluminum indicate as silver most of the time. Just the way it is. On the other hand, one time I thought I was uncovering the end of a can and turned up a plain, but large silver ring.
luvsdux

 

[Diggin-N-Dumps]

its the name of the game brother..Only time with your machine can fix that

Best of luck man!!

 

[Jason in Enid]

Your metal detector CAN NOT perform metallurgical test. It puts an energy wave into the ground and looks at what energy gets returned. The VDI is only telling you where on the scale of possibilities that target falls. This means that very tiny silver will read much lower, very large aluminum will read as silver, and rusty iron can read all over.

Also keep in mind, that because this is all about "energy" that the shape of the target GREATLY affects the signal return. Detectors LOVE round objects, especially ring shaped items, they give the best returns. Everything other than that is a crap-shoot as to how it will read.

 

[Diggin-N-Dumps]

I think there are ALOT of people under the misconception that machine can distinctively tell the difference between metals, and materials....if that were the case...all the Gold would be Far Gone by now

 

[TheRingFinder]

halgreene - It is all in the audio, I haven't looked at my screen in years. A rusty nail will give a high pitch sound, though it is a different sound then silver. After years of detecting, you WILL figure this out. Another trick is when you get that high pitch sound, turn 90 degrees on it and pass your coil over it again, the sound will disappear or change; then you know it's junk. Hope this helps - good luck!

 

[Pistol60]

Hello Hal, I've found as Susan (above) mentioned raising your coil up a foot or so and see if your still getting a signal it probably is trash. Coke cans and such are notorious for this. As an "older" digger I tend to be very conservative with my bend downs and stoops.

 

[Silver Searcher]

halgreene - It is all in the audio, I haven't looked at my screen in years. A rusty nail will give a high pitch sound, though it is a different sound then silver. After years of detecting, you WILL figure this out. Another trick is when you get that high pitch sound, turn 90 degrees on it and pass your coil over it again, the sound will disappear or change; then you know it's junk. Hope this helps - good luck!

It's a just waste of time looking at readings, and numbers on a screen, like Jason said the shape of a object can make a huge difference, I still dig ring pulls, iron washers and basically anything that is round in shape.

SS

 

[Tom_in_CA]

Hal, the ring-finder is right: There will be tell-tail clues for larger cast-iron, versus a true high conducting coin. Try swinging momentarily faster over the suspected target, and you'll see that larger cast-iron will have differences, versus if it's a silver or copper coin.

Also luvsdux is right too: That it's not only conductivity that plays into the ultimate TID (silver versus aluminum versus etc..). But also SIZE that plays into it. So for example: wave a snippet of aluminum cut out of a can (or just wave the tab), and you'll see it comes in low, tab, or whatever. Right? Ok now wave an entire soda can. What does it read? Penny or quarter or whatever, right? But notice that in each case the composition NEVER CHANGED. In each case it was still the same: aluminum. Ok then what changed? SIZE. So sometimes you can guage the commensurate size of an object, versus the TID. So for example while the TID of a shallow flattened can may read "quarter", yet the pinpoint size of a quarter is distinctly different than that of a full can.

 

[JunkShopFiddler]

I've always been told it's the size that fools the detector. A big piece of iron or aluminum will have the same amount of conductivity as a small piece of silver. The advice to lift the coil and ignore it if it still signals is right. Another thing I have done is step around the pinpointed spot and scan the target from the other direction. Say you are scanning east to west, step around the spot and scan north to south. A lone round object will usually sound the same both ways. A long or irregular shaped object will sometimes sound good one way and not the other way. But beware, this is alright to do in a trashy park only because if you dig everything you could end up with pounds of junk. I will dig more questionable signals in a residence or less trashy place because a buried cache may give just the type of signal that you want to avoid in a trashy place...Or...you could just dig 'em all and sort 'em out later...Damn the can slaw, full speed ahead!

 

[MUD(S.W.A.T)]

Because trash is very vain...

Keep @ it and HH!!