[ Post a Response | Alberta Metal Detecting Forum ]
Posted by Pennies from Hades on November 19, 2007, 7:20 pm, in reply to "There is no way to change the properties of matter and energy....this formula.."
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As pointed out in my orig. post. It's all about degree of corrosion. Metal detectors all measure parameters associated with induced current - flowing ON THE very SURFACE of the target. If this surface happens to be corroded .. well then all bets are off and it's gonna cut through all manner of discrimination (and show up all over the dial). Rust (either iron oxide or copper oxide) is a non-stoichiometric substance and as such, demonstrates unusual electrical properties. Namely, semi-conductivity; very much similar to the semi-conduction of doped-silicon; the building material of modern electronics. So lowly old rust is chemically and electrically pretty exotic .. this spells a heap of trouble as far as discrimination is concerned. Rusty items, on the other hand, often offer-up forensic clues in relation to what-the-heck happened here? So something to be said for rusty (and corrosion-resistent wrought-iron) objects getting past the discrimination. All things being equal; think of it as an age filter. And rest assured all standard coil-type detectors including PI machines, ONLY measure SURFACE properties (including halo-effect and geometery considerations). Points tend to cut through filtration. A modern (shiny) beer-cap will be completely 'extinguished' whereas; a folded-in-half, rusty old beercap will cut through. In part due to the rust and in part due to the pointy ends. So we are still kinda chasing our tail .. we have to think further 'outside the coil' if we want greater partition ratio. Stay tuned. Thank you for your contributions. : )
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