Usually the tan is 15lb.. However, I have some 22lb. that is also tan.
If its samples, I'm sure it was 15lb.
Anyway, you'll probably want to lightly sand it and give it a heavy coat of prime. When it dries, lightly sand it again and then prime it again. Once this coat dries, inspect it very closely and look for any areas that might pop or have not completely filled in. If there are any areas like this, sand again and re-prime one more time. You can use something like Jay Cooke's primer. It's really good for this stuff and is somewhat thick. Don't thin it down, use it as is and don't add anything to the paint.
Once this is good and dry.... I'd use metallic silver 1Shot based on your level. Besides, chromes and mirror finishes are hard to get to last outdoors. If you feel brave..... highlight it and shadow it by adding colors to the silver to help enhance the effect you want. If it doesn't work, just wait for it to dry and give it a final silver coat again. If you want to clear it, that would be fine if you used 1hot.
Also paint the back side to be sure its fully coated.