2k primers and paints are two part paints that require you add an activator. 1k primers and paints are air activated by the solvents evaporating. 1k products are extremely unstable and that is why they don't last long. I only use epoxy primers on bare metal because it creates a rock solid barrier. Then a high build primer, then paint. I lean towards DuPont products, but it depends on what which product and application. For aluminum, you want to etch it before priming. I forget the name of the chemincal, but it is in several products like Purple Power. Scrub the aluminum with Purple Power and a gray Scotch Brite pad, then rinse with water. Do that tree times. On the last scrubbing, make sure the Purple Power is rinsed off and not allowed to dry on. If it does dry, just do it a forth time. It doesn't matter. Do not wipe with solvents afterwards. What I like about Purple Power is that you have to clean the aluminum anyways, so you're killing two birds with one stone. I have had great success painting aluminum this way. A friend with DuPont taught me this, so I cannot take credit. I am not a professional painter, so I am always bending his ear. One thing he repeatedly emphasize to me is not to use 1k primers and paints. 1k products like Por-15 are awesome, but that is a whole nother animal. Hope this helps.