I like the idea of using a black primer. It will mask imperfect spots, add depth, etc. Because I'm new to airbrushing, I know I won't apply a base coat uniformly and a black primer will likely mask my errors.

However, I'm not sure how much a black primer will darken the base coat (in my case, dark yellow). I wouldn't want to make my WWII German tank models look "blackish yellow." Any thoughts? FYI, I'll use acrylic paints (Vallejo primer + Tamiya base coat).

The vallejo primers are the best on the market and airbrush nicely. The black primer will give you shadow density. Tamiya Dunkelgelb is on the light, yellow, green tint side of the color, so a black primer would help. Go for it.

Yea go for it spray the Yellow as lightly as you want to, show as much of the black through as you want. i'd keep it to shadowed areas a much as poss Geraint

I always use black primer for my models. Personally I think Citadels Chaos black is great. It gives an evenand very matt finnish. It comes in an aerosol spraycan, so you don't have to clean your airbrush afterwards.
Best regards
Jacob

Chris;

Black primer is GREAT under dunkelgelb! I use Floquil RR enamel "Engine black" - super fine-grain, super tight adhesion. Spray the yellow any way you like to bring up shadows, wear-thru to "original" / prior dunkelgrau coats, etc. And yeah, IF you have any concerns about the yellow coat looking too dark, lighten that yellow (great for doing some panel fades, too!).

Bob

I'll just try a black primer to see if it works for me.