DIY Conductive Shielding Paint recipe

[Christopher DBG]

I was not happy with the Stew Mac water based conductive shielding paint, especially for the price. 24 hours between coats was too long, and two out of three times I've used it there were adhesion problems. Large pieces flaked off leaving bare wood.

The one I came up with turned out very good and is simple to make, just shellac and carbon. I had a bag of "furnace black" around for years that is used to turn clear varnish into black varnish, but you can buy GRAPHITE and it's the same thing.


First put some shellac flakes in a jar and add about double the thinner as flakes.





It's not enough thinner to dissolve all the flakes, so it makes a totally saturated shellac mixture. Give it an hour or two and a couple stirs, then poured off about 2 tablespoons into another jar. Add carbon until the mix is at it's limit. If you have ever added corn starch to water, it acts the same way. It's kind of a liquid and a solid at the same time once you hit the limit of carbon you can add.

This is in it's semi-solid state:


This is with about 1/4 teaspoon more thinner and it's totally liquid:


Then add more thinner, about 2-3 times as much as the shellac/carbon mixture. Enough to thin it out so it spreads nice and even with no clumping on bare wood. If it starts to clump on the second or third coat add a teaspoon at a time more thinner until it flows on well.

Three coats with 1-2 hours between each, and the multi-meter reads as low or lower resistance than the Stew-Mac paint.

 

[rufus.K]

You're my hero

 

[DiabolusInMusic]

That is pretty awesome and fairly cheap. The Stew-Mac stuff isn't worth the price they charge. I am assuming you tried MG Chemicals Supershield before all this. It's great, you can spray a bass in about thirty minutes and most of that is waiting for the paint to dry.

MG Chemicals Super Shield™ Nickel Conductive Coating

 

[Christopher DBG]

That is pretty awesome and fairly cheap. The Stew-Mac stuff isn't worth the price they charge. I am assuming you tried MG Chemicals Supershield before all this. It's great, you can spray a bass in about thirty minutes and most of that is waiting for the paint to dry.

MG Chemicals Super Shield™ Nickel Conductive Coating

No, I didn't but that looks great and I will try it some day. I'm in the middle of building six basses and when the Stew-Mac stuff flaked out on me (pun intended) I needed something immediately since two of the basses have no outside access to the control cavity once the tops are on and I was about to glue the tops on. All the electronics are fed through the pickup route like this:

 

[walterw]

I am assuming you tried MG Chemicals Supershield before all this. It's great, you can spray a bass in about thirty minutes and most of that is waiting for the paint to dry.

MG Chemicals Super Shield™ Nickel Conductive Coating

beat me to it!

one 30 second spray coat, dries in like 3 minutes, and vastly better conductivity than that messy, slow-drying black paint.

two coats and it approaches copper foil shielding conductivity.

it also adheres perfectly well to plastic, so you can shield pickguards, back covers and such easily.

 

[Christopher DBG]

beat me to it!

one 30 second spray coat, dries in like 3 minutes, and vastly better conductivity than that messy, slow-drying black paint.

two coats and it approaches copper foil shielding conductivity.

it also adheres perfectly well to plastic, so you can shield pickguards, back covers and such easily.

Well, I'm glad I posted this even if it was just to find out there is a much better way! I'll be ordering that before the next group I build for sure. The liquid version only comes in quarts and the cost is $175. Still, probably worth it in the long run.

 

[walterw]

One $30 spray can was enough for like 15-20 guitars as I recall.

 

[DiabolusInMusic]

Well, I'm glad I posted this even if it was just to find out there is a much better way! I'll be ordering that before the next group I build for sure. The liquid version only comes in quarts and the cost is $175. Still, probably worth it in the long run.

It's about $50 CDN a can for me, I get a handful of basses from each can. I spray it into a cup when I need some brush on.

 

[earlysecond]

I think I asked what could be used before. Much, much respect! First, all those awesome basses not this recipe! Bonus points and atta boys.

Gonna order the supplies. Add it to some solvent based inter coat and spray it as a test. After I mask and spray and compete the cavities, I can clear right over top of it in the final coat.

I forgot that carbon was conductive, or I never knew it!

Thanks Smithcreek!

 

[Christopher DBG]

Gonna order the supplies. Add it to some solvent based inter coat and spray it as a test. After I mask and spray and compete the cavities, I can clear right over top of it in the final coat.

If you haven't used a carbon based conductive paint before just make sure you mask really well and don't get any on bare wood that you don't want it on. It's almost like a stain, it gets deep in the wood fast and could definitely cause trouble.

 

[MarkoYYZ]

+1 for the MG Supershield. One heavy coat or two regular coats and you're golden. Bonds well, dries quickly and in my case, is made about 25 miles away, so I get to support a local business. MG makes other products we use in my lighting biz as well.
.

 

[Bruce Johnson]

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.

 

[earlysecond]

Bruce- Does it matter that whatever you put in the cavity has conductivity at the surface? Yeah, I guess it all needs to be connected. BUT before the cure the copper, or whatrever we are talking about will fall out of suspension to the bottom. I would think that you need a real thin vehicle to suspend the particles that way there are fewer paint solids and more conductive solids.

I may be thinking about this wrong. . . and effective Faraday Cage, based on my research can be made of almost any conductive material. I read several articles that said any metal, regardless of relative conductivity was good enough, as long as the entire surface was conductive to itself at any 2 points.

I am not adverse to brushing what Smithcreek came up with. I just want to use paint I have lying around!

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! I will order some graphite today! Until it arrives and I mess with it and start a new build where I can apply it before the paint then I will stick with my aluminum flashing tape from Lowes. . . .remember, any metal will suffice and I will tell you that aluminum works mighty fine but the tape takes awhile to work with, but then so does copper at 10X the price!

 

[Christopher DBG]

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.

The first mixture I tried was yellow glue, water and carbon and that was pretty much a failure. Very low conductivity. So low that I assumed that the furnace black was the problem and I needed some kind of "special" carbon, but l figured I would try something solvent based and I had the shellac around.

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. The "recipe" I came up with may not be the best, but it does work in that there is enough carbon to conduct and enough shellac to hold it together. Plus, it's easy to follow, super-saturated shellac, as much carbon as it will take, thin to brush-able consistency.

Yesterday when I was going to post this I wanted to find a source for carbon since most people would not have furnace black sitting around, so I did a quick google and found the product linked to above. A couple of the people that reviewed that carbon said they used it to make conductive paint and it worked great. One guy specified that he mixed it with Future Floor Finish.

 

[Hopkins]

I've done my experiments as well, and all have been failures. I've tried zinc and copper weld through paints, and I have tried two different brands of magnetic paint and they all resulted in an open reading on my meter when testing them.

I will stick with Supershield from now on.

 

[DiabolusInMusic]

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.

Bruce- Does it matter that whatever you put in the cavity has conductivity at the surface? Yeah, I guess it all needs to be connected. BUT before the cure the copper, or whatrever we are talking about will fall out of suspension to the bottom. I would think that you need a real thin vehicle to suspend the particles that way there are fewer paint solids and more conductive solids.

I may be thinking about this wrong. . . and effective Faraday Cage, based on my research can be made of almost any conductive material. I read several articles that said any metal, regardless of relative conductivity was good enough, as long as the entire surface was conductive to itself at any 2 points.

I am not adverse to brushing what Smithcreek came up with. I just want to use paint I have lying around!

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! I will order some graphite today! Until it arrives and I mess with it and start a new build where I can apply it before the paint then I will stick with my aluminum flashing tape from Lowes. . . .remember, any metal will suffice and I will tell you that aluminum works mighty fine but the tape takes awhile to work with, but then so does copper at 10X the price!

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. I had one can slowly leak out on me due to my lack of care. I now setup a piece of scrap before I spray so I can immediately turn the can upside down and blast out the tip. I have yet to make that mistake again and I have used cans over extended periods of time without issue.

 

[BogeyBass]

Or a roll of tin foil at the dollar store
but basic copper spray paint is highly conductive too

 

[earlysecond]

Tin foil fine. . . as long as it works. Results- all that matter in my mind.

 

[Hopkins]

Or a roll of tin foil at the dollar store
but basic copper spray paint is highly conductive too

It may be fine for your bass, but it is definitely not fine for a professional who has to do a professional job.

What kind of copper paint are you referring to?

 

[PDX Rich]

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.