Correlation between air testing and ground testing coins:huh:

[wagon wheel]

Can some of you more experienced folks shed some light on this topic for me? I have never taken the time to establish a coin garden nor have I taken the time to pay attention to the depth of a certain coin while detecting and then run an air test on it once I've dug it out of the ground to correlate the data for comparison...how close will the two distances be? I plan on doing this process this next season...but I'm hopeful that you good folks can share with me any knowlege you've gained on the topic from your years of detecting.

Much thanks for your good help.

w.w.

[BOWSER]

i don't have any faith in air tests as they are too simplistic in thier results,wet ground here in massachusetts seems to enhance your finds and type of soil effects results in changes of results effecting electric components.JMHOP jim

[russellt]

when you air test a coin you are getting results that are unskewed by ground mineralization and trash. in addition you never know how a quarter will look if its got an iron nail next to it in the ground . when you air test a target you basically are eliminating all the variables you encounter in the field. but it does give you a benchmark to work around. i noticed you have a V3 and a dfx . i ve owned both units. most times the deeper a target the more varying the vdi #. jumping --if you will. but tone ID should lock on those deeper targets.you may not get a consistant vdi # but the tone ID will lock on the target in the ground and beep on consistant coil swings over a target..do yourself a favor and bury some coins in your yard . mark where the targets are with golf tees so you dont lose anything .they are made of wood so it wont effect the detector . hope this helps

[Dimeman]

There is some difference in air testing and an actual coin that has been in the ground for a while. The halo effect that is around the coins and other targets are the natural and unatural minerals in the ground that attach to the item and on corrosive metals make it seem larger than the item is. That is why some very small iron pieces when you dig them break up and the halo disappears and the target vanishes.
You have seen the color of clad coins that have been in the ground a few weeks, and iron that rusts. Copper pennies and nickels that turn color and get a patina on them. That is the minerals attaching to the metal.

Gold and silver is non corrosive so those items made of it, look like they did when they were lost.

[v3ikid]

I just did an air test for the first time. I agree it is just a starting point and things will be different in the ground. No doubt though if your machine won't read a coin in the air it won't get it in the ground. The only accurate test you will ever do is to dig everything. Even if you do that and get EVERYTHING and the possibility exists that you can squeeze another inch or two from your machine then you will still have more to dig.

[jkress]

Where I detect, the ground has minimal mineralization. Air tested coins end up being very close to how they read when naturally dug... excluding any influence from surrounding metal items.

By the way... love the dynamic tonal range in your avatar.

Great post.

[giant056]

In my whole metal detecting career I've never even had a test garden and doubt I ever will, I just got hunt and try to dig the good stuff.

[Vito]

Hi w.w.,
air tests are good if you want to confirm some waved targets; if you know how to setup the detector for air testing. And you can compare the power of equal detectors, i.e. two M6's (same setting used).

But if you're using a programmable detector like the XLT, DFX, v3, e-trac, explorer and so on, I think a coin garden is a must have.
Having a test garden for many years. One target is a quarter sized brass part 8 deep. The mxt with the 6x10 will get it easy. When Carl, a friend from the U.S.A. was here, he couldn't get it with his 4900/D Pro-Plus (very bad soil here), while the CZ-70 picked it up while the coil was 3-4 inches above the ground. Carl was very amazed. And Carl knows how to use his detector as he found some great coins and buttons in the field.
When I had the v3 it took me 4 hrs of tweaking the machine to run stable without to much falsing getting this targets in the test bed.

So, there is time to use an air test, and there is time when a test bed can help ya.

Vito