gleaner1
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- Feb 1, 2009
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M-Badger's post got me thinking about the ever-debated "halo effect" and its relationship to detection depth in wet or dry conditions. I think that most people would agree that wet conditions allow deeper detection.
Why is that? The halo effect becomes more pronounced when wet.
Detectors are sensitive to metal oxides. Silver oxidizes. US silver coins have 10% copper which oxidizes even more and adds to the mix. Where does the oxide go? It leaches out around the coin. Add water, conductivity increases, and the halo effect becomes more pronounced. Fertilizers are salty, adding even more to the effect. Copper and brass have even more halo effect because they produce a lot more oxide around the target.
On iffy targets, not too deep, in dry soil, that I think might be a nail, I push the spade deep an inch or so to the side and "move" the soil in the target area just a little bit. This disturbs the matrix "halo" around the target and if the target is iron, the signal drops out. If the soil is wet enough, I can mash my boot heal down onto the target area and get the same results. Why is that? Iron halo effect.
The halo effect and the soil moisture effects go hand in hand. You cant have one without the other.
Dry conditions are better to hunt for silver in iron infested areas. The oxide "halo" surrounding iron is less reactive when dry, decreasing masking, allowing silver to come thru better. When I go to the trashy sites, I wait until its bone dry, and I have better results.
I wouldn't worry about detecting in bone dry soil. I can find dimes at 6 inches with an old Garrett Freedom II. If I am really on a deep seeking mission in trash free areas, I like wet, but I think the difference is only an inch.
Wet or dry, halo or not, just learn your machine and hunting areas and you will get the deep ones for sure.
There are always trade-offs in detecting.
Why is that? The halo effect becomes more pronounced when wet.
Detectors are sensitive to metal oxides. Silver oxidizes. US silver coins have 10% copper which oxidizes even more and adds to the mix. Where does the oxide go? It leaches out around the coin. Add water, conductivity increases, and the halo effect becomes more pronounced. Fertilizers are salty, adding even more to the effect. Copper and brass have even more halo effect because they produce a lot more oxide around the target.
On iffy targets, not too deep, in dry soil, that I think might be a nail, I push the spade deep an inch or so to the side and "move" the soil in the target area just a little bit. This disturbs the matrix "halo" around the target and if the target is iron, the signal drops out. If the soil is wet enough, I can mash my boot heal down onto the target area and get the same results. Why is that? Iron halo effect.
The halo effect and the soil moisture effects go hand in hand. You cant have one without the other.
Dry conditions are better to hunt for silver in iron infested areas. The oxide "halo" surrounding iron is less reactive when dry, decreasing masking, allowing silver to come thru better. When I go to the trashy sites, I wait until its bone dry, and I have better results.
I wouldn't worry about detecting in bone dry soil. I can find dimes at 6 inches with an old Garrett Freedom II. If I am really on a deep seeking mission in trash free areas, I like wet, but I think the difference is only an inch.
Wet or dry, halo or not, just learn your machine and hunting areas and you will get the deep ones for sure.
There are always trade-offs in detecting.
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