I think you are right Rigit, that if a machine couldn't pick the coin out next to the iron in the air it would be harder for it to do in ground for the iron has a heck of a large halo in comparison to any coin. Twice this week I dug out large nails, pulling them straight out of the side of the hole and when I went back in with the probe I could still pick up the rusty iron particles still around where the nail used to be. Next coin you pull out in the same manner, try and pick up it's halo in the soil it was sitting in, I have never been able to do it, but I have done it many times with iron. I am going to make less friends with this next statement, in that,
I do not believe silver leeches out of any silver coin enough to increase it's signal because it's halo would be too small and on copper coins; that green crud is literally doubling the surface area of the coin and also leeching some into the soil while pitting is falling out. As for nails and iron in general, not only do they leech massively in comparison to coins but again the corrosion is doubling and tripling, possibly quadrupling their surface area. Don't believe me, how many pitted silver coins have you dug lately?? But I think Bart has a point to be taken quite seriously in that if you were swinging over a nail at 3 inches deep (which would give a much larger signal) and then right after a coin at 7 inches, which not only be a smaller signal to begin with on a level playing field, but now that it's twice the distance from the coil, it's signal is probably now minute in comparison. Nothing like guessing which color the invisible ghost is. That maybe the largest argument for the air tests being very inaccurate, when the iron nail is out of the ground without it's leeched rust halo, it's signal is going to be much smaller then in ground, haloed, and many of these tests that work above ground won't mean much once the nail is haloed in ground and those same results will no longer work in ground. I think that's why we need appreciable moisture to get real depth on silver. The iron has a tremendous advantage in signal size and when the soil gets wet; it, in itself, carries the much smaller signal of the silver further then it would in dry non conductive ground. Add salt, and it's even more conductive. Ever make a battery in school and add salt to the water and watch the light bulb light where water itself couldn't carry the charge and the second you stirred in the salt, it lit up nice and bright? But not only is moisture increasing the distance of the silver signal "carrying" but it is also doing the same for the iron signal, even more so. If the silver had a signal "size or strength" value of 3 and the iron a value of 6 and moisture doubles the value of the silver but triples the conductance value of the iron, the silver value is now (2x3) 6; and the iron's now is (3x6) or 18. So at that time, a smaller coil would need to
both be able to fit in between the two pieces of iron, not having their stronger signals interfere with the detection of the silver but also have to be able to carry the 7 inches of depth necessary to pick out the coin at 7 inches deep, where the week before, when the soil was dryer, you couldn't reach the silver because you would have needed a larger coil to get 7 inches depth and maybe the larger coil is now too large to achieve the separation needed between the two nails and the machine then nulls out, because it never picks up the minute signal of the silver coin in size comparison too the two nail's combined signal together. But there may be a tiny exact spot where the coil in that exact spot can receive just enough to give a peep, but with discrimination, the strength of the return signal may be too small for the machine to report over the null. That signal may never be heard in discrimination. That's what all metal does, the machine reports everything, not just if it is larger than the null or everything else, just if it's larger than the threshold setting, which means it can be much smaller and still be heard. Sometimes that signal is equal to the threshold level and the threshold will blank alerting you to a vary small or deep signal. How can you tell your threshold is "blanking" if you are in discrimination? It would just sound like a null. That's what gain is supposed to do, to "boost" the strength of the signal higher than the threshold but again the machine is deciding this for you. Most of this software that does all this "compare and decide", you could do in half the time with your ears. All these discrimination filters, and if/then filters turn the signal into a rumor and each filter is a new person it has to pass through, by the time it gets around the room, it does not resemble the original and the information is wrong, sometimes opposite from it's original form. I want my all metal, ML. See how I took your air test post and turned it into an all metal plea.
I have a disease apparently. By the way if anyone doesn't agree with what I posted and/or it doesn't make sense, either you're not smart enough or I just made it up as I went along.
