Red or black

[discrunner]

I noticed that some of the new primers are now in black as well, when would I use the black rather the red primer, why the 2 colors if i'm just using as primer??

[Rustyolds]

I noticed that some of the new primers are now in black as well, when would I use the black rather the red primer, why the 2 colors if i'm just using as primer??

I'm thinking of painting the frame and one might prefer one color or the other if you think one would be more visible which would help get good coverage with the top coat.
Also if you use a red primer and some top coat should at some time chip off you would have a red spot showing.