I have a can of primer. It directs to thin it down and spray it.
I would rather not spray.
So what happens if i try to roll or brush it on straight from can?
Even primer/surfacer (some call it high build primer) is supposed to be sprayed in fairly thin coats so that it dries completely between coats. There's no reason you can't roll or brush it BUT you'll need to make sure it's dry all the way through before sanding it and it will take a long time to dry. It it's too thick it'll feel dry but still be un-cured underneath. If you shoot a top coat over it before it's totally dry you can have issues with the top coat.
