DIY Conductive Shielding Paint recipe

#21
PDX Rich said:
Copper slug tape is cheap, but can be tedious working in tight areas (where it is normally used!). Small cuts on hands also no fun.

I plan to buy some of the MG stuff for sure.

Aluminum foil--nope! Tears easy and looks way too cheap to complete a 60+ hour project with.
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I recommend getting tape with a conductive adhesive online from Ebay or Amazon, the cheapest stuff is straight from China and marginally more than slug tape. Slug tape doesn't use conductive adhesive.
 
#23
earlysecond said:
Guys- I suffer from an affliction called cheapness, to a fault and it often makes a fool of me. $30 for a can that will likely not stay pressurized long enough to use all of, or $175 a quart. . . .uh, no!
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how much is your time worth? how good of a shielding job do you want to do?

i've long since stopped bothering with anything besides the supershield, the other methods just seem like silly wastes of time, and of those, the only one that's nearly as good a shield is full-on copper foil. (one decent coat and a couple minutes of drying time will give me like 40Ω resistance from one end of a large cavity to the other. if you bother with a second coat you can get that down to like 4Ω. graphite paint results in more like 4kΩ.

as for the loss of pressure problem, read the directions on the can!
DiabolusInMusic said:
With Supershield you really need to ensure you spray out the tip, small pieces of graphite get caught in the tip and keep it open.
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this.

hold the can upside down and spray until totally clear, and you can put it away confident there won't be any blobs of escaped goop on the nozzle when you go to it weeks later and it'll still be full.
 
#24
Yeah, I did the upside down cleaning per their instructions. But I still had two or three cans that leaked down when they were only partially used. That was a few years back. The last 4-6 cans I've bought haven't given me any problems.

MG does sell the shielding in liquid form, but it's expensive. Even the copper shielding. I suspect that one of the secrets of how it's made, and the reason why it's expensive, is that the metal powder has to be ground to a very small size. Much finer than the powders that we can easily buy. That's what allows it to get through a spray can nozzle, and probably makes it so conductive in the paint carrier.

I just noticed on MG's data sheet that their base paint is an acrylic. I don't know what that means in terms of conductivity, but it obviously works for them. The MG Super Shield Nickel in liquid is $175 for 900ml and $435 per gallon. I may eventually spring for a 900ml can. A quick calculation says that's about 30 fluid ounces. I don't know how spraying that through a spray gun would compare in cost to buying the spray cans.
 
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#25
walterw- I'm not sure how to value my personal time. Right now, there is nothing I would rather do than build, in fact, out of the last 4 days I am on a binge where I pushed though a couple of 10 hour days to finish and came up a hair short and out of a couple materials necessary to finish. For this, I used 2 vacation days from work.

I guess I should remind myself that I am a hobbyist. So, at this point, it my shielding works and I use chewing gum wrappers. . . it is unimportant (plus they are inexpensive, free if you only count the gum not the packaging). I am in a mode where this is all practice, so I think it is time for me to stop questioning the price of stuff. Hardware, pups, and now shielding paint.

Just got an email with some logo options in it and so IF I decide to go to the next level, I will open the wallet! haha Funny, when it came time to paint a car valued at 19K, I still ended up making my own base coat for less then half the price. It came out OK.
 
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#26
Bruce Johnson said:
Smith, that's very interesting. I've been using the MG Nickel SuperShield for many years, and really like it. My only complaint is with the cans wanting to slowly leak down and lose their pressure....and leaving big puddles of expensive nickel in my paint storage cabinet.

About a month ago, I tried an experiment, to mix up my own shielding paint. I wanted something that I could keep in a jar and spray through an old touch-up spray gun. I bought some fine copper powder and mixed it into some Varathane water-based polyurethane, which I use for my regular painting. The experiment was a failure. The result was far too thick to be sprayed through my gun. Even when I brushed it, it wasn't very conductive. I assumed that either the copper powder wasn't fine enough, or the polyurethane was insulating the particles too much.

Your experiment with using shellac as the base is encouraging. It sounds like you are getting decent conductivity, even with the carbon powder. There may be something about the shellac that makes it better suited for passing the conductivity between the particles. I'll have to try mixing the copper powder into shellac, similar to the way you've done it.
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I had a can do that to me too.
 
#28
OK, now it is time for me to spray graphite. I have 2 options- solvent based poly intercoat (almost like basecoat without pigment) OR Water Based poly, the ProFinisher which is on the rest of the build. I am going to assume I need a large fluid tip for my gun. I have a 1.8 tip if I can find it easily otherwise I will go 2.0.. I am going to make this mix as thick (viscous) as I can and still spray it. I will let you know how I make out.

Next, I would assume the proper test would be 0 resistance through a multimeter set to read ohms? Right.

Final question, the control cavity will likely have a metal lid on this build. It should complete the Faraday cage because it is metal and as long as it makes contact with the graphite should work.

I am making a lot of assumptions here. Is my thinking sound? If not I found really inexpensive copper tape today and will order some of it. I hope I can pull this off. If I do it will be great not to have install metal shielding inside of an otherwise completed guitar body!
 
#29
earlysecond said:
OK, now it is time for me to spray graphite. I have 2 options- solvent based poly intercoat (almost like basecoat without pigment) OR Water Based poly, the ProFinisher which is on the rest of the build. I am going to assume I need a large fluid tip for my gun. I have a 1.8 tip if I can find it easily otherwise I will go 2.0.. I am going to make this mix as thick (viscous) as I can and still spray it. I will let you know how I make out.

Next, I would assume the proper test would be 0 resistance through a multimeter set to read ohms? Right.

Final question, the control cavity will likely have a metal lid on this build. It should complete the Faraday cage because it is metal and as long as it makes contact with the graphite should work.

I am making a lot of assumptions here. Is my thinking sound? If not I found really inexpensive copper tape today and will order some of it. I hope I can pull this off. If I do it will be great not to have install metal shielding inside of an otherwise completed guitar body!
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I have no insight on spraying your mix but you want the resistance to read as close to 0 ohms as possible. A metal cover will work fine already, you will not need to shield it. Lastly, when you order copper tape ensure it has conductive adhesive. I get mine from Ebay but lots of folks use Amazon, just don't use Stew-Mac.
 
#30
I don't know why I didn't see it before, but here is some pre-mixed water-based conductive copper paint. Much less expensive/oz than the MG liquid, and can be thinned as needed for spraying. It's sold by Caswell, the home plating place, for pre-coating non-metallic parts to electroplate them. But, they say it was developed to use for EMI shielding. $40 for 4 oz.

Amazon.com: Copper Conductive Paint

I'm going to order a bottle and give it a try. I'm thinking I'll dedicate one cheapo airbrush or touchup gun just for spraying it. Pour it in the gun, spray two coats, back in the bottle, minimal paint waste. And no more leaky spray cans!
 
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#31
Bruce Johnson said:
I don't know why I didn't see it before, but here is some pre-mixed water-based conductive copper paint. Much less expensive/oz than the MG liquid, and can be thinned as needed for spraying. It's sold by Caswell, the home plating place, for pre-coating non-metallic parts to electroplate them. But, they say it was developed to use for EMI shielding. $40 for 4 oz.

Amazon.com: Copper Conductive Paint

I'm going to order a bottle and give it a try. I'm thinking I'll dedicate one cheapo airbrush or touchup gun just for spraying it. Pour it in the gun, spray two coats, back in the bottle, minimal paint waste. And no more leaky spray cans!
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That look very encouraging. It says it can be used on plastic, and most paints that will stick to plastic have no problem with wood.
 
#32
Top coat poly is still drying so I cannot tell you how I made out yet. I will share a couple of observations. My mix was graphite heavy in water based poly. This was practice as much as anything because this project has active pups. I sprayed it too heavy because I had a really narrow fan on a really big gun. I went on fine and thick but cracked as it was drying. A second coat was not too good at filling in the cracks. I will test if for conductivity tomorrow and let you know. I sprayed the control and pup cavities. Sadly, I have little faith that this particular attempt was very successful BUT I will not know until tomorrow.
 
#33
earlysecond said:
Top coat poly is still drying so I cannot tell you how I made out yet. I will share a couple of observations. My mix was graphite heavy in water based poly. This was practice as much as anything because this project has active pups. I sprayed it too heavy because I had a really narrow fan on a really big gun. I went on fine and thick but cracked as it was drying. A second coat was not too good at filling in the cracks. I will test if for conductivity tomorrow and let you know. I sprayed the control and pup cavities. Sadly, I have little faith that this particular attempt was very successful BUT I will not know until tomorrow.
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You put it right on the instrument? I did a couple days of tests with different recipes using different ratios of varnish, graphite and thinner and different number of coats on scrap wood. As I posted before, "I tried a few different mixture ratios and it seems the less shellac and the more carbon the better, which makes sense, but at some point with too little shellac it did not hold together and started to crack after the second or third coat." I did test the conductivity of the ones that cracked and it was not good. It will be interesting to see if yours is the same.
 
#35
No dice! I checked it with the multimeter and there is no conductivity. Again, it does not matter on this build but will in the future. Here was my thought, put something sticky inside the cavity to coat the internal area then dust the graphite into that binder, whatever it is. If it were thin enough it could actually accept a good bit of graphite. I am thinking that epoxy or solvent based clear coat would work pretty well. Wait, I prefer anything that i can spray. If I was not about done spraying clear on this project I would try it but I fear, at this point, it would make a big mess!
 
#36
Bruce Johnson said:
Smith, that's very interesting. I've been using the MG Nickel SuperShield for many years, and really like it. My only complaint is with the cans wanting to slowly leak down and lose their pressure....and leaving big puddles of expensive nickel in my paint storage cabinet.

About a month ago, I tried an experiment, to mix up my own shielding paint. I wanted something that I could keep in a jar and spray through an old touch-up spray gun. I bought some fine copper powder and mixed it into some Varathane water-based polyurethane, which I use for my regular painting. The experiment was a failure. The result was far too thick to be sprayed through my gun. Even when I brushed it, it wasn't very conductive. I assumed that either the copper powder wasn't fine enough, or the polyurethane was insulating the particles too much.

Your experiment with using shellac as the base is encouraging. It sounds like you are getting decent conductivity, even with the carbon powder. There may be something about the shellac that makes it better suited for passing the conductivity between the particles. I'll have to try mixing the copper powder into shellac, similar to the way you've done it.
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I have had 2 cans do this recently.With what they cost I got pissed and ordered the carbon conductive coating from the same company. Absolute Garbage.

https://www.amazon.com/gp/product/B01N01RNFS/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Unfortunately I didn't try it until I ran out of the other so I can't return it.
 
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#39
I have been through a few cans of the nickel. Some getting a lot of basses and some coating less. The can on the right is the last on that wouldn't stop draining no matter what I did.
Nickel coating.jpg
 
#40
tjclem said:
Yes i do that with all my spray paint. I have had some cans do great and others I can't get more than one bass out of. This product correct? https://www.amazon.com/MG-Chemicals...01N3AWGNX/ref=cm_cr_arp_d_product_top?ie=UTF8
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Yes, that's the SuperShield Nickel in spray cans that I've been using for about ten years. I've gone through about 12 cans; I've had two that leaked down so far. The product is wonderful overall, except for that problem of the cans sometimes leaking. I haven't kept an accurate count, but I'm shielding maybe 10 bodies per can.

The can I have now is getting low, and I have a batch of basses coming up through the summer. So I may go ahead and try the Caswell copper shielding that I mentioned above. Since I already have a whole spray booth and rig and multiple guns, it may make more sense to have one more cheap gun set aside, always loaded with the copper shielding paint.
 
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