Originally Posted by Jim1611
Another problem you'll have is in the process itself. The part is submerged in 5 different tanks throughout the process and each has to drain off when it's lifted out of the tank. There are places where the liquid will get trapped and taken to the next tank which will cause problems. Another thing that will happen is air will get trapped in pockets as it's lowered into the tanks so not all of the metal will get treated correctly.
When I had my boat trailer dipped, the company gave me specific instruction on where to drill 1/2" or larger holes so that the various liquids could drain. They also warned that attempting to submerge an airtight frame into hot zinc would cause the air to expand and possible deform (bulge) the steel tubing. In addition they didn't want hot zinc getting blown all over when something came apart. I did what they said, and the trailer came out beautiful. Still looked good when I got rid of the boat/trailer seven years later.
Hot dipped parts aren't meant to be top coated either. The zinc is applied thicker than zinc that is electroplated. When I worked at the plating company most of the zinc plated parts went out either with a 'bright dip' (faux chrome) or a di-chromate (yellow) finish.