Air testing and test gardens

I recently seen a Facebook post that someone had just purchased a new metal detector. One of the first things they did after assembly was throw some coins on the ground and give it a try. His post on Facebook was talking about how disappointed he was with the air testing results on concerning depth and asking people for their opinion. I was disappointed with several of the answers telling him things like “I would send it back” and “my same metal detector will go deeper”

That post really got me thinking and I wanted share with you when air testing and test gardens are used and why. This has been a subject that I have shared with many people over the years and I hope to clear up some confusion especially with those new to the hobby.

 Air testing

This simply means running your metal detector over targets that are not buried in the ground. To start, find a spot in your yard with the metal detector that is free of targets. Then take some common coins, relics, even trash like a pull tab, chunks of aluminum etc and lay them all out in your grass spread out so there is plenty of space between them. Raise your coil an inch or so off each target and run your metal detector over each item. Go through the items several times if you wish and LISTEN to the target. You are not trying to see how deep the detector will go, do not waste your time putting iron close, next to on top of or below a target just simply listen to the tones and look at your VDI number to give you an idea of the numbers.


Test garden

I’m not going to go into how to design and build a test garden (I don’t use them) but what you want to do is bury some objects at different depths in a designated area in your yard. Now this test garden can be used to compare coil depths and how one metal detector handles deeper targets compared to another. It is also good way to tweak your settings. If you have a dime at 8 inches and your metal detector isn’t picking it up, try changing your settings.

 Let’s break down air testing first

I do not mean to offend anyone but too many people will throw down a few coins to air test and they get less than satisfactory results as they move their coil above a given target. I have also seen the opposite when it comes to putting bad targets next to good targets or nails on top of or underneath good targets. Something that has bothered me for a long time is reviews on metal detectors where someone will share the results of air tests. The ones that really bother me is when they compare multiple metal detectors from air test results. I have used a lot of the different detectors that I have seen tests done and I can tell you so much of this is false! Claims that one machine is better in iron from air tests is ridiculous!

Let’s look at test gardens

It is very difficult to use a test garden to really get any kind of real world knowledge from it unless your garden is an acre lot. There are way too many scenarios to really get a true feel for a metal detector from a garden. Why you ask? When you are out metal detecting you are going to find targets at all different depths with iron around some, junk around others, you will find multiple coins in one hole, depending on your area there are hot rocks, mineralization, the list goes on and on and it’s just not practical to try and make a garden and expect it to give you real world results. Again, a test garden is great to try and tweak programs for depth, compare coils and compare metal detectors when it comes to depth. It’s not even good to try and determine the depth potential of any given machine unless your garden has been there for several years.


How to REALLY learn your metal detector

 Use air test to just get a feel for the tone and VDI numbers. Even then I wouldn’t put too much into the VDI numbers because most likely they will be different than something that has been buried and in the ground for years. Put about 10 targets within range of your detector but at the deeper depths to tweak programs and compare coils. Once you have a feel for the detector now go out and metal detect! I am sorry but that’s the secret to learning your machine, its depth capabilities, how it will handle different ground conditions such as mineralization and iron. Go out and dig targets, shallow, deep, dig junk and before you dig any target listen to the response, watch your VDI numbers closely until you are comfortable enough with your metal detector that it feels like an old friend and you give her a cute girls (or boys) name!

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