I plan on painting the wiper arms on my truck black. I have a sand blaster to take off the paint thats left. Once I blast it I plan on primering the arms and then paint them black.
Should I sand the primer surface so the base coat (Black) would have a mirror finish or do I just primer it, paint it, then wet sand the base coat, then paint it again, then clear it? I hope I make sense.
I am trying to learn to paint by myself so I'm not sure of the process.

Also, How do I mix the paint and thinner to make sure I have the right mixture for painting. Is there a standard parts per ounce of thinner to paint? I am using an Airbrush kit that I purchased on ebay.

If it was me, i would just use a spray can of flat black on the wiper arms. You dont want them blinding you with the sun.