Dunno...That is, unless it's a primer for making the paint stick better to vinyl tracks... But for me, the Base Color for tracks is Steel and if they have pads, they get painted Testor's Rubber. After that, I weather them.. I like to have stuff painted factory -fresh then weather it, same as in the real world...
I've just bought my very first Vallejo paint set (face-painting colors) but haven't tried them yet... I've been using regular enamel, oils, & acrylics for so long, I'm not sure I can learn a new way, lol...