So for the Black Widow company, I was considering using a black base coat and then painting white highlights and then over painting the white with red. For Kell Hounds should I prime white or gray then apply red and black base coats?
So, I'm sure some of the pros will disagree w/ me here, but, when I'm doing a scheme that involves major amounts of Black/White/Grey, then I prime in that color heavily & it works as primer/base coat.
Now, in the case of putting Red on Black, yeah, I end up having to do my Highlights a few times because yes, putting bright red over black will leave you showing black through quite a bit, but, I'll take that any day over having little bits of Grey/White that just refuse to get covered & keep peeking through when I'm doing a Black/Red or Black/Green scheme.
I was doing Jade Falcons Epsilon last year sometime IIRC & it was a royal PITA when I'd think I'd completed my Black/Green only to find little tiny spots of White/Grey primers on this little crack or that little edge.
I had run out of Black Primer but still had the White & Grey so I thought, no big deal, well, yes, it was a big deal, total pain to try & get black or green into every nook & cranny on just over a binary of mechs.
I should note that I don't own an airbrush & everything is brushes except primer coats from the old rattle cans.
PS. I should also note that I have WAY too much Red v/s my White which is down to the last bottle, so for me, going over highlights w/ extra Red is fine v/s the White undercoat you mentioned.