The "MATRIX" revisited...

[GT]

Hope you weren't expecting to come here to watch Neo kick Agent Smith's butt across the virtual landscape. Nope, this post will more mundane but I hope, still interesting.

Objective:

Create an artificial "matrix" or "halo" to see how it affects your detector's ability to sense a coin.

Why create an artificial "matrix"? Because unless you want to wait months or years this is the most practical why to see how a matrix affects your detector. Plus you get the added benefit of having consistent soil conditions over the testing period which makes for more reliable results. Long periods of times cause soil conditions to change (changing moisture content, temperature, organic matter, etc.) and will skew results. This experiment will isolate the "matrix" effect.

Materials Needed:

Get your favorite detector with fully charged batteries, a copper penny, a shovel or trowel, a spray-bottle full of water, and a few oz. of copper sulfate or copper chloride crystals (from a garden supply store).

Instructions:

1) Find an area free of excess mineralization and trash to run this test.

2) We will use a copper penny and copper sulfate (or copper chloride) for this experiment because of the ease of procuring copper sulfate (or chloride) crystals.

3) Dig holes of various depths and bury the penny until you've found the maximum depth the penny can be sensed by your detector. Make sure to compact the soil the same amount each time to keep things consistent. Make sure your detector has been ground balanced (if not a preset model) and optimized to get the best depth with the least amount of background noise. Do not change your detector settings once you have set them up.

4) Now dig up the penny leaving the hole empty. We are going to re-bury the penny at the same depth but before doing so take the spray bottle with water and spray the soil under where the penny will lay. Make sure the soil is good and wet. Place down the penny and add a half inch of dirt on top of the penny and spray the dirt (on top of the penny) with water until it is good and moist.

5) Fill the rest of the hole in with dirt (again compact it the same way you did before.)

6) Check to see if you can still detect the penny as you did previously. Your detector should hit on it the same, UNLESS, you have lots of minerals in the ground that got activated by the water you sprayed. If this is the case, you'll have more work to do.

7) If your signal increased due to the water spray, you'll need to re-dig your penny and place it deeper, each time make sure to spray the area below and above it with water so soil conditions remain constant. Again find the maximum depth it takes for your detector to sense the coin.

You can skip step 7 if your detector hits the penny the same with water sprayed above and below it.

9) Here comes the fun part. Re-dig the penny. Sprinkle copper sulfate crystals in the dirt underneath where the penny will be (at the same depth). Sprinkle an area that is about 3-inches in diameter. Spray the copper sulfate that you placed down with the water bottle so that the crystals start dissolving and the solutions penetrates into the underlying soil.

10) Place the penny in the middle of the 3-inch circle of wet copper sulfate crystals. Now sprinkle a half inch of dirt on top of the penny and sprinkle more copper sulfate crystals on top of the dirt. Spray the crystals so they are good and wet (some dissolved solution should soak into the soil underneath.)

11) You have just formed a "matrix". The dissolved copper sulfate should behave like corroded copper around the penny.

12) Fill in the rest of the hole and check to see what affect this has had on your detector.

This is a bit of work and I'm guessing not many people will try this, but if you have the spare energy post your results.

My results will be forthcoming this or next coming weekend.

Have Fun!
GT (Western WA)

 

[Tagamet]

Don't forget to test a hole that has JUST the wet copper sulfate (no penny).
Tagamet

 

[John in Florida]

It's always been my contention that the best target signal is possible wihen the target is moist.

The situation is reversed in high mineralization. When mineralized soil is wet, there is less signal penetration and much more ground noise.

This, by the way is a seperate issue from 'halo'.

I don't believe halos are a significant factor with silver coins. JMHO.

John

 

[rentasquid]

But I doubt that you will ever find a penny that will leach or dissolve enough copper to equal the amt of CuSO4 that you are salting the soil with. If you do find one, there wouldn

 

[GT]

J you're right here. But we're more interested in what effect the ionic solution is having on the detector. This test will exaggerate the "halo" effect by making a bigger than life "halo". Of course the smaller the "halo" the smaller the halo affect will be.

Copper sulfate is a plant fungicide. So if your tree roots are infected by a nasty fungus, they'll appreciate the copper sulfate treatment.

 

[GT]

Right John! This makes perfect sense. Moisture activates ions in the ground. If you have corrosion around a coin it takes moisture to free up the conductive ions tied up in the corrosion products (making the coin look like a bigger target.)

Now if you have lots of mineralization in the soil, in other words lots of natural occurring ions that conduct electrons in the soil. These too will get activated by moisture and will provide a huge ground signal which will interfere with the signal coming from the coin.

Gold does not corrode in the ground and so does not form a halo. Silver is another story, it corrodes to form silver sulfides and silver chlorides. Neither of these corrosion products have high dissociation constants (they do not form conductive ions readily) so even though they corrode the matrix doesn't contribute much in generating additional eddy current.

Copper, brass, zinc, tin, and iron are the metals that form conductive halos.

 

[GT]

Noted, this would be a good data point too!

 

[rentasquid]

n/t

 

[John in Florida]

Yea, I always worried about those 'dissociation constants'


John

 

[BarnacleBill]

1. Take 2 empty clean margarine containers 3 inch dia. more or less.
2. Dig 2 holes, put copper penny in one container, center it, fill with soil, compact. This is your control target.
3. Take another container, repeat step 2 and add Ferric Chloride solution(used to etch copper from printed circuit boards), pour into container till soil is moist. This is your halo target, bury.

In 24 hours you'll have a halo you wouldn't believe. Check your control hole against your halo hole.

Ferric Chloride must be handled with care, and will stain anything it comes into contact with like hell. Use eye protection and rubber gloves if you are clutzy. It is available from hobby places and on the web.

Etch on brother, etch on.

HH
BarnacleBill

 

[GT]

I like your idea Bill, it's simpler than mine to execute. Looks like I'll be visiting the hobby shop for some ferric chloride.

Muy Gracias Senior BarnacleBill!

 

[Mike Hillis]

After you do this one. Do another. Find a old 'deep' target. The really deep ones that have been in the ground for awhile and deep enough that you can barely pick it up. Try to retrieve it undisturbed inside a dirt "ball" if you will. Now take this dirt ball and bury it at the same depth you first found it. See if you can detect it now. Leave it there and see if you can ever detect it again. How long will it take the soil matrix to re-establish itself after being disturbed and how long to interact to the new substance introduced to it?

I think the "instant" corrosion test method completely removes the soil matrix interface. Yeah, you're corroding a object, tying it conductively to the imediate soil around it and making it look bigger, but I think you are missing out of the whole soil matrix affect.

Your idea is good. Bill's idea is good. The next step is to include the whole matrix. I think John brought this up before talking about targets in plowed fields vs targets in unplowed fields.

 

[BarnacleBill]

.

First a warning, some of these methods use house mains AC voltages of 120VAC 60Hz and it is very dangerous if you don't know what you are doing. I assume no responsibility in simply providing the references, I am NOT encouraging anyone to try any of this. If you get your butt killed, I don't want to hear from your widow's attorney that I told you to do this.


See the following:

http://www.amfone.net/ECSound/K1JJ12.htm

http://www.antennasbyn6lf.com/files/ground_parameter_measurements_2.pdf#search='soil conductivity arrl ac'

http://www.arrl.org/tis/info/tech.html


Next issue;

When you say plowed field, it can mean many things, plowed into furrows? How high? How wide? Granular soil? Large clods? Small clods? Hot rocks mixed in? Tilled, turned over? Dry, or wet and settled?

Everyone here may be holding onto a different part of the elephant.

I believe there are possibly other factors outside of disturbed soil, because that explanation appears overly simplistic.

I'd like to throw in two other mitigating factors.

Machine, what machine are you using, how does it like a quickly gained and lost ground signal, i.e. swinging over a furrow cross ways. This is equivalent to bobbing the coil while swinging over flat land. What kind of depth do you expect in that circumstance? Many machines in high mineral conditions will false at the end a swing if you let the coil rise. Is this not the same condition passing over furrows? So how you swing may be a factor.

And what machine you use may be a factor, fixed GB, autotracking GB, high freq, low freq, good w/ hot rocks, fast target recovery.

There may be people in your area who favor certain machines for plowed field hunting for a specific reason, i.e. I believe Bill Ladd & Mr. Bill like the Exel ID for certain fields because it ignores a particular hot rock very well. I have seen posts from down south where people love the Cibola & Vacquero in the clay.

And now for an un-paid political announcement.

You can experiment until the cows come home(god knows I like to also), and you can spend a whole lotta time reading opinions from self appointed experts who talk a lot, but just don't seem to get around to posting all those finds. But you have to get out and just hunt, this hobby should be about gettihg out for some fun, NOT talking about getting out.

I have dug thousands of targets in the last year, just do an all forum search for my screen name for all dates. Some days have been better than others, but it all beats sitting at home typing on the computer, unless you are sick or laid up.

It's now 6am EST, I have been up since 2am, it is now time to plan today's hunt to a virgin beach that will involve a 1.5 mile walk along a shoreline w/ Barnacle Jr..

HH
BarnacleBill

 

[GT]

This was a disappointing weekend. I searched hardward stores and hobby shops for 50 miles and was not able to find copper sulfate or ferric chloride to run my matrix tests. I did find some online suppliers but after adding shipping costs it becomes an expensive experiment.

I will still run the tests but it will be after I find an inexpensive source of either ferric chloride or copper sulfate (sorry to get everyone over excited about this without returning a weekend result).

GT

 

[GT]

n/t

 

[GT]

n/t

 

[rentasquid]

We use Copper Sulfate here in our lab, but dont think the Super would take kindly to hijacking a bottle.

J.

 

[GT]

Hi J.

I used to have a bottle of it in the garage and thought I still did until this weekend when I tried looking for it and couldn't find it. Oh well, I'm sure I'll come across some eventually so I can run this test.

Thanks anyway,
GT

 

[John in Florida]

Ferric Chloride is used as a circuit board etching solution, I believe.


John