Here is a link to the AlcladII page.
http://www.alclad2.com/alclad-home.html
If you are using one of the high shine finishes your base coat should be a highly polished gloss black. Quote from Alclad site "ALCLAD High Shine -Chrome and Polished Aluminium both require a dark glossy base. Polished Aluminium should be used over Tamiya TS-14 gloss black,or gloss black auto paint. Chrome and only chrome should be used over gloss black model enamel paint."
Any other finish should be sprayed on a very smooth finish. A grainy primer will ruin the finish.
If you are using a primer it needs to be polished before applying the Alclad.