DIY ESD Paint

by Frizz on Sat Oct 19, 2013 1:23 pm

If you have priced ESD paint, then you know what kind of money it will set you back. I had this idea:

Get some powdered graphite and mix it well into the paint. I got the idea when I thought up a similar concept for making slip-resistant paint for stairs: Stir in some coarse sand. I googled up a DIY site that had sand/paint proportions ready to go.

I have NOT found anything for DIY ESD paint, and certainly nothing on proportions. Graphite isn't the only substance, but it is what came to mind.

Soooooo... any ideas?
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Re: DIY ESD Paint

by adafruit_support_mike on Sat Oct 19, 2013 4:41 pm

ESD protection is one of the black arts in electronics. The general rules of thumb are "don't believe anything you haven't verified instrumentally", and "don't trust your instruments too much either".

The classic work on the subject is "Grounding and Shielding Techniques in Instrumentation (3rd ed)" by Ralph Morrison.
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Re: DIY ESD Paint

by Frizz on Sun Oct 20, 2013 7:25 am

I'm gonna interpretamate that reply as "DO NOT TRY THIS!"

I'll just be sure to use the ESD mat, but I'll test it first. Since it is a black art, I'll also put a pinch of graveyard dirt on the floor under the bench.
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Re: DIY ESD Paint

by franklin97355 on Sun Oct 20, 2013 1:16 pm

I wouldn't say 'do not try this' More like test your results and don't depend on it as your only option. Don't forget the chicken bone on the shelf above the bench, you do have a shelf don't you?
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Re: DIY ESD Paint

by adafruit_support_mike on Mon Oct 21, 2013 7:33 am

Yeah, sorry.. didn't mean to come across completely negative.

My intended point was that ESD is one of those areas where the gap between theory and application is extra wide. You need to know the theory to avoid the basic pitfalls, but then you need to build, measure, and tweak to work out all the non-obvious but important details.

And don't forget the safety dance. You *never* forget the safety dance. ;-)
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Re: DIY ESD Paint

by Frizz on Tue Oct 22, 2013 3:45 pm

Post by franklin97355 » 20 Oct 2013 18:16
I wouldn't say 'do not try this' More like test your results and don't depend on it as your only option. Don't forget the chicken bone on the shelf above the bench, you do have a shelf don't you?


I decided not to do it because I don't have enough understanding of ESD to guess where I should start with a graphite/paint ratio. I would only go to the effort to design something easy to make that I could share with others. Even if I did come up with a simple "x grams of graphite to y litres of XYZ latex paint #OINOU2", I would be uncomfortable since my sample size would be small, and paint formulations change frequently.


I'm going to add the shelf soon. As soon as I do, I will add the chicken bone. (Ritual slaughter at midnight using a silver knife?)
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Re: DIY ESD Paint Redux

by Frizz on Wed Oct 23, 2013 4:54 am

OK, so I'm obsessive compulsive to a degree, and I'm going to give the latex paint w/graphite DIY ESD paint for a wooden workbench top a try.

I am going to try to mix powered graphite with latex paint to get something. I know that it will not be precise. I know that the result will depend on the paint formulation, and purity, grain size, and grain uniformity of the graphite, and the thickness of the coat of paint. I am going to mix the holy bajeezus out of the mixture to try to eliminate that variable.

I think the big questions are:

1) What ratio of graphite to paint should I start with, and what should my increments be? (Should it be in grams/graphite to liters paint or grams/graphite to grams/paint?)

2) Should I put a coat of plain paint with the graphite-doped paint on top, or should it just be a coat of doped paint? (Or two coats?)

3) What should my final Ohms be, and what measuring technique should I use? (Ex: XOhms with leads 10cm apart.)

Anything else?


My disclaimer also applies to anyone who provides suggestions and/or observations. I will post my results, the materials I used, and what I did. There will be no promises or guarantees/warranties. It may reduce your risk, but it may do nothing at all; it could make your situation worse. Test what YOU do. You should still follow all EDS-safety rules because quality-control for this is worthless.

If you want something more reliable, buy the $US150/gallon ($US 39.63/l) stuff. Better yet, get one of those $US 800+ workbenches instead.)
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Re: DIY ESD Paint

by adafruit_support_mike on Wed Oct 23, 2013 4:40 pm

To get conductivity, the graphite particles have to touch each other. The latex matrix will hold them apart, so you'll want a fairly high concentration of graphite. This Instructable uses a 3:2 graphite-to-matrix ratio: http://www.instructables.com/id/Conduct ... nd-Conduc/

To measure the resistance of the final product, tape out a 1" square and run copper wires across two opposing edges. Paint the square in a way that makes contact with the whole length of each wire, then measure the resistance between the wires.

Resistance is a material property, so in practice it depends on the geometry of the object. One side-effect is that resistance is independent of scale.. the resistance between opposite sides of a square will be the same no matter how large the square is. That follows from the basic resistor equations: putting two 1 ohm resistors in series gives you a resistance of 2 ohms. Putting two 2 ohm resistors in parallel gives you 1 ohm. If each 1 ohm resistor was a square of material, a 2x2 pattern of such squares will still have an edge-to-edge resistance of 1 ohm.

If you use fairly large copper wire (12 gauge would be good if you have some sitting around), the resistance of the wire will be a few orders of magnitude lower than the resistance across the square, so it won't even count as a rounding error in your readings.
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