i've tried a few black gloss primers or undercoats which ever term fits best.
i've used tamiya Acrylic Black Gloss. then i used Alclad Black Gloss. Then i used Enamel Black Gloss.
when they say in the instructions, to use enamel black gloss, they're pretty much right from where i'm standing.
Enamel gives the best and toughest black gloss out of all three that i have used. it's even tougher than the "lacquer" Alclad Black gloss. for some reason, my alclad black gloss keeps on rubbing off with my fingers. and i let it dry and cure for like 2 days. and they just come off on my fingers. it's like the heat from friction just melts it or something.
Enamel also has a more shiny and reflective quality to it. and if you want your alclad metal finishes to be shiny, you will need a shiny black gloss.
i don't know if they sell Future, where you live or i'm not sure if it is called Future in Denmark, but you can also use this to make the black gloss even more glossier. mine became pretty glossy. you can see yourself in it now.
hope this helps.