For those who wish to dip paint. I had asked this question to some knowledgeable people and ended up with this answer. Here is what I am pulling back out of my brain so hopefully I am not messing up any details.

Using a 55 gallon drum full of water and a couple of gallons of enamel paint they painted some wheels.

The wheel was hung from a crane and slowly lowered through the paint into the water and then slowly pulled back out.

The results were mostly excellent. The problem was from small droplets of water that stayed on the paint when pulling back through the paint for the second coat. The dry paint had great coverage and shine and it was pretty easy painting the pesky wire wheels. The down side was that fact you could not really store the set up and you need to consider the water droplet problem which was not a problem on the factory line.

On the factory line they had a real big tank. The parts were on a very slowly moving overhead conveyor. The conveyor had a gentle slope into the tank. The parts slowly were dipped into the tank and the slow linear speed through the tank created a flow around the parts. So when they were pulled back through the paint layer the paint flowing past the parts helped pull the water droplets off of the surface.

That is the quick and simple of dip painting as I understand it.