Conductive Powder Coatings?

Question:

 I enjoy your column and all of the solutions you and some of the readers offer. I am responsible for sourcing sheet metal suppliers for a long-time-in-business, large corporation with "remote" engineering sites. The final assembly plant for these products is in "environmentally correct" California. We are having a problem with an older sheet metal design, which uses liquid paint that is conductive. My sheet metal supplier is forced to use a paint shop that has a "grandfather" license for spraying the stuff. This all works well until we have a spike in demand or the holidays show up and we (my sheet metal supplier and I) get held hostage as to the delivery quantity or delivery date. Can you recommend a specific "powder" solution (powder manufacturer or direction we can go in) that is conductive (custom formulation to yield custom conductivity)? The liquid paint we use is about 1,000 ohms/sq ft in measuring the "resistance/conductivity." The base metal is cold rolled steel, looking like an erector set once assembled and welded (not very large surface areas). The powder can be black in color and must be friendly in retaining a silkscreen. Any help or suggestion would be appreciated. R.F.

Answer:

Thanks for your loyal readership. It's great to hear from a person who likes my sense of humor and creative solutions to every day powder coating problems. Having said that, your problem is not considered an "every day" problem, or I'm just not very creative today. In either case, I know of no powder coating that is considered a conductive coating, especially to the requirements you need (1,000 ohms/sq ft). Clients of our consulting practice have had similar products to yours and use grounding lugs and masked areas to transmit the required ground from part to part. If they use masked areas, these parts are often plated or anodized first to protect against corrosion. Sometimes the means of assembly will transmit the required ground (screws, rivets, etc.). Anyways, your method may be expensive, but may be the best and simplest way to achieve your goal. I recommend you find a more cooperative supplier for this coating service. There can be a lot of "grand-fathered" suppliers just looking for the opportunity. The best way to find one is to contact the liquid paint supplier to find out whom else they sell to in the area. Good luck.