Hallo Ray,
if you´re working with Crome or HP Alu, you have to take Black or at least a dark grey for the base. It will create the best metal effect. If just applying 1 or 2 coats of Alclad, the base will always shine trought a bit, thats why I love preshading with this stuff! Just spray the panel lines with a medium grey - no more base - then alclad, 2-3 coats. You´ll get a wonderful effect! Remember to brush with no more than 1,5 bar! (10 psi)
You can use that blue Base anyway, just apply a few more coats of alclad. The blue shade will fade away. Personally I received the best results with white alu, using the other shades only to point out some panels on a natural metal finish.
Hope I could help!
Liebe Grüße aus Österreich!
Jerry