Crude coil sheilding paint

[Kev]

Egg white can be a good glue base -- save it!..

had to re-read my post before it sank in!

Thanks AP I'll look into that product.

I've just used two 'CATHODE' (wrongly called them anode above) carbon rods ground to powder with a dremel and mixed with a little plastikote paint. It worked out well, giving about 2kOhm per inch, but my 4500 doesn't like it, and refuses to ground balance.

A graphite paper shield from an original Minelab coil measures about 45 - 100 Ohms all over, so I think I need to get the resistance way down below what I have.

Cheers Guys.
Kev.

[simonbaker]

Hi,
I'm very sorry, this preparation is way too corrosive, it has over time turned my ground wire connection to oxide powder.

The carbon needs to be extracted from the manganese dioxide and other chemicals and washed carefully before adding to the paint....maybe better to use graphite powder instead, if you can get it, or just use the powdered carbon anodes from the battery.

{Washing egg from face}
Kev.

Egg white can be a good glue base -- save it!

Thanks for follow-up -- no problem, all in a day's tinkering. Worth the experiment to find out the facts.

Now -- you can still use your idea if you take some of that gold you find and make a non-corrodable shield wire out of gold ...

[ApBerg]

Hi,
I'm very sorry, this preparation is way too corrosive, it has over time turned my ground wire connection to oxide powder.

The carbon needs to be extracted from the manganese dioxide and other chemicals and washed carefully before adding to the paint....maybe better to use graphite powder instead, if you can get it, or just use the powdered carbon anodes from the battery.

{Washing egg from face}
Kev.

Hi Kev,

Thanks for warning !

... searsing on Ebay I found this.. is powder and must be mixed with water.
Made some small tests, must say I like it. Is easy to paint and tools can be cleaned with water . I sticks 'good' on ABS plastic.. if you keep in mind that it is on waterbase !!
The multi meter like's it also, dry is it some 500 Ohms / 10 cm, think this is dependend on the thicknes from the paint layer .

Best regards.

Ap

http://www.ebay.de/itm/Kreidezeit-Abschirmfarbe-1kg-Pulver-29-95-kg-/280590927608?pt=LH_DefaultDomain_77&hash=item415485c6f8

http://www.ebay.de/itm/Kreidezeit-Abschirmfarbe-1kg-f-ca-20-qm-NEU-OVP-49-Euro-/250943672404?pt=LH_DefaultDomain_77&hash=item3a6d689054

[Kev]

Don't use this paint!

Hi,
I'm very sorry, this preparation is way too corrosive, it has over time turned my ground wire connection to oxide powder.

The carbon needs to be extracted from the manganese dioxide and other chemicals and washed carefully before adding to the paint....maybe better to use graphite powder instead, if you can get it, or just use the powdered carbon anodes from the battery.

{Washing egg from face}
Kev.

[mts]

How do you attach a ground wire to shielding that is made out of paint? I'm assuming that a ground wire is still required in order for the shielding to work its magic.

[ron_o]

Just a thought!

Has anyone tried Aluminized or Crome Paint?

Hi homefire,

Aluminium and Chrome based paint use metallic flakes which are normally coated with a chemical that prevents the carrier resin blackening the flakes. This coating acts as an insulator and prevents electrical conductivity between the metallic flakes , so i doubt that they would work in this application.

Regards ron

[homefire]

Just a thought!

Has anyone tried Aluminized or Crome Paint?

[Kev]

Hi Eric,
Thanks for sharing that, it all makes sense now, no wonder it was making goldfield ground balancing so difficult

Eric, I would also like to take this opportunity to extend my warmest condolences to you, and your family for your sad loss. There are a lot of people around the world who really care about you, and will always be grateful to you for your open contributions to metal sensing technologies.

Kind regards
Kevin Murta.

[grungymike]

custom shielding paints.

Yipes, I was gonna pay $35 + shipping for that nickel spray! Think I'll do a little more research first. One possibility comes to mind, there's a product called "coppercoat". It's a spray adhesive used on head gaskets during engine assembly. It's got colloidal copper in what I think is an acrylic polymer base. No idea what the electrical characterisics are like, might be worth trying. Same thought for some of the fine powdered metal flake additives used in custom automotive paints. As I'm thinking (?) while typing, I wonder if part of the reason soot or carbon black works well has to do with the REALLY small particle size, as well as high conductivity.

I'm still working on building a control box, haven't gotten to coil building yet. Learning more every day from this site though...

gm

[Ferric Toes]

I resorted to using Electrolube Nickel loaded paint, but my Minelabs don't like it, plus the cost is exorbitant nearly $60 US per can where I live, although that's retail, and not the trade price.

Hi Kev,

The likely reason that nickel paint upsets Minelabs is because it is magnetic. If you look closely at the receive waveform of a nickel paint shielded coil, you will see a decay curve that is not due to conductivity but caused by magnetic viscosity. I have also tested nickel paint in my magnetic susceptibility meter, and my soil viscosity meter, which confirm the above. A nickel paint shielded coil often buzzes or sings when it is powered up due to its reaction with the pulse field and the coil shell acting like a sounding board.

Eric.