Electric Charge on Paint

Last night's "How Its Made" had 2 examples of charging paint. They stated that positively charged paint was used on the fire extinguishers and negatively charged paint was used on the shock absorbers. I know that opposite charges attract, but I have never gotten a good "gut feel" for the charged paint process. Some people have told me that it does make a difference where you use the positive and negative charges, others say it doesn't. Last night's show added to the confusion.

Does it make a difference if the paint is positive or negative?

Also, how much voltage is used and how much electrical current "flows" as the charges move with the paint?

I have had X-military people tell me of painting with one side of a car battery attached to the car/truck and the other terminal attached to the paint gun. Will this work? Isn't this a big risk of welding the paint gun to the car, or at least getting a spark and fire in the solvent-rich paint vapor? They told me that you can only paint one or two cars/trucks until a fully charged battery will go dead. That seems like a lot of charge to transport through the air on paint droplets.

Is the distance between the paint gun and the target critical? The airborne charged paint particles should try to find their way to the opposite charge (distance not very critical) but it seems like the amount of charge that the paint will "pick up" would be dependent upon the strength of the electric field that the paint gun is exposed to (distance is critical). Any ideas?

Many years ago I had several tours of Whirlpool and Ford factories. I recall in one of them (I think it was Ford) there was a robot controlled spray booth. The paint dripped down a shaft and onto the top of a spinning circular platter. The platter was charged and spinning rapidly. The object to be painted went past the platter (one side only) and was "magically" painted. We were looking through a glass window and I did not see any overspray on the window or on any surface in the paint booth. Did I miss something or is the charged paint technology really that good?

The above example was NOT painting inside a round object. A horizontal circular spinning disk was "slinging" paint and a flat panel (I don't recall what it was) was moved past one side of the spinning disk. The disk did move up and down to fully coat the panel, but there was no motion or spray shields to prevent the disk from slinging paint toward the window that I was looking through.

Is it possible to use the "charged paint" technique with water based, oil based, latex, enamel, epoxy, and all other types of paint? How about "normal" vs. "metal flake"?

I'll probably never use any of this, but still it bugs me.

Thanks,

Bruce