What should I consider when choosing a metal primer?

In choosing a metal primer, you should consider several things. First is to know what you are painting. Metal, especially when cut into thin sheets, is very prone to expansion and contraction due to temperature changes. You should find a primer that is flexible enough to withstand these changes. Next is to know the characteristics of the paint you will place over the primer. Use paint that is elastic enough to deal with the expansion and shrinking of the metal and your primer must be able to do so as well. Finally, apply primer that has anti-rust and anti-corrosion properties to protect the metal from the harmful elements.