EMI Shield Spray for Search coils?

[SVEN1]

I need to pot a DD search coil that has arrived.
Initially the coil has been build using enamelled magnet wire, nulled. Shielding has been done to the inside of the coil shell with carbon spray.

Was told they pot using 2 steps.
Fill and cover coil windings with a layer of epoxy.
Let cure, then use carbon shield spray over the epoxy, let cure.
Then final layer of potting epoxy.

My question is, I don't have carbon spray on hand.
I do have MG Chemicals Super Shield #843 EMI/RFI spray paint. http://www.mgchemicals.com/downloads/tds/tds-843-a.pdf

I am guessing this will work fine for use in covering the first layer of epoxy?
Any comments?

[Chet]

Hi Sven
That is some coating! It has extremely low resistance! I would prefer using the carbon spray. It has higher resistance and lower capacitance. This spray will be similar to using solid copper or metal foil. The coil will not be as fast. But if coil speed is not needed for small gold or jewelry it should be ok.
If you do use the copper/silver spray be sure that you use masking tape to mask a separation gap somewhere around the circumference. This gap will prevent having a shorted turn around the coil.
Have a good day,
Chet

[dfbowers]

I need to pot a DD search coil that has arrived.
Initially the coil has been build using enamelled magnet wire, nulled. Shielding has been done to the inside of the coil shell with carbon spray.

Was told they pot using 2 steps.
Fill and cover coil windings with a layer of epoxy.
Let cure, then use carbon shield spray over the epoxy, let cure.
Then final layer of potting epoxy.

My question is, I don't have carbon spray on hand.
I do have MG Chemicals Super Shield #843 EMI/RFI spray paint. http://www.mgchemicals.com/downloads/tds/tds-843-a.pdf

I am guessing this will work fine for use in covering the first layer of epoxy?
Any comments?

Hey Sven.
Have you ever used "Blaster " graphite spray? I use it to shield my clam shells all the time. I pick it up in at a local Home Depot.
Don.

[6666]

Hey Sven.
Have you ever used "Blaster " graphite spray? I use it to shield my clam shells all the time. I pick it up in at a local Home Depot.
Don.

Don is this the stuff you use ?
http://www.amazon.com/Blaster-8-GS-G.../dp/B0094IZ3BA

[dfbowers]

Yes that's it. Blaster is a name brand I think so you just need to pick the right stuff.

[Point]

printing right now the second part of my diy md project there i work with cat7 and graphite spray i can tell you later how it work with it
but from the bottomplate corner to corner ~180mm ~26k Ohm

[6666]

Thanks Don and Point, just found a possible supplier of 8GS,here in Australia, it will probably be $100 a can by the time the USA to Aus dollar conversion and the "Australia" tax is added
just sent them an email, be interesting to see what they say. Probably have to buy it by the box full.

Point from pictures I've seen of Cat7, it has heavy internal shielding, be interested in how it works for you.

[Nupi]

I have used with good results.
Solvent Based chalkboard paint (carbon/graphite).
You can apply it with a brush or spray.

You should try it experimentally to dilute and try the number of layers for the necessary resistance about 1.2k ohms per square.

Ohms per square is explained below.

http://www.edn.com/electronics-blogs...ms-per-square-

https://www.youtube.com/watch?v=ME4Xe53TMxI

[FatBob]

I've used this stuff, it's a paint;

http://www.tractorsupply.com/tsc/pro...l?cm_vc=-10005

[DOOLEY]

also available in the uk !!!!!!!!!!!!

http://www.plccenter.co.uk/en-GB/Buy/BLASTER/8GS

[SVEN1]

MG Chemicals also has a carbon EMI spray . http://www.mgchemicals.com/products/...e-coating-838/

But if Blaster will work as well, I should be able to find it locally. My biggest concern is the ability to adhere to the first layer of epoxy and the 2nd layer of epoxy.
Since its not a chemical bond, just a mechanical bond. Is there a chance the carbon spray will eventually cause the two layers of epoxy to separate, especially if used
in water hunting situations?

[6666]

Solvent Based chalkboard paint (carbon/graphite).

Thanks will try it.

[bernte_one]

have ome questions:

chalkboard paint, solvent based - is it sure that it contains graphit?
not better to mix some clear laquer with real graphit powder?

ordinary graphit spray - normally used as lubricant - i am not sure that the epoxi will glue on it

i think the best is still i shielding spray / paint like emv35

http://www.amazon.com/Conductive-Shi.../dp/B00CFSJ8F8

http://www.amazon.de/KONTAKT-CHEMIE-.../dp/B00154KONS

[Nupi]

I used kontakt-chemie 33, but I prefer to use blackboard paint. (Flexa blackboard paint)
The information I received from Flexa blackboard paint are the primary substances: carbon, graphite, alkyd-synthetic binder, solvents,..........
The advantages are:
- A good adhesion to different materials.
- It does not stain.
- It is relatively inexpensive.

[SVEN1]

Searching out the blackboard paints, just noting that from what I can see "so far" is they only have 1% carbon black filler in them.

Found some interesting stuff:
https://books.google.ca/books?id=yTP...0paint&f=false



http://krc.cecri.res.in/ro_2006/107-2006.pdf




http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&ved=0ahUK Ewjc1LjE0vrLAhVjnoMKHeWnCXUQFghDMAY&url=http%3A%2F %2Fwww.cabotcorp.com%2F~%2Fmedia%2Ffiles%2Fguides% 2Fspecialty-carbon-blacks%2Fapplication-guide-conductive-carbon-black-for-use-in-acrylic-and-epoxy-coatings.pdf&usg=AFQjCNEM02Hkzicud4nkLfTa4dWG0kLwX w&sig2=vF5AfZtf8GyybxBe5TuubA&cad=rjt