Step 4: Priming the frame and other parts
Ah the step we are all waiting for, painting. Hold up there turbo, before you paint make sure the area where you are working is clean and as dust free as possible, to insure that no dust is floating in the air that could land on the wet paint and mess up your work. Also you well need a way to hang the bicycle up so you can easyly paint the whole frame in one hit. I happen to have a nice beam going across the celling of my parents garage, which aside from painting bicycles I have painted a guitar, pulled and engine and also hang model airplanes from. Take a peice of stiff wire, say a coat hanger, and fashion a hook to hang the bicycle from and to loop over what ever you are hanging the bicycle from. Hang it up.
Now for the fun part get out the primer. Read the directions on the back of the can, and kick on the fans if you are working in an inclosed area like me in a garage, with the door open of course. No seriouslly do it, the directions on the back of the can are there for a reason(and are often quite helpfull), and the fans are a must, paint fumes are nasty and if you start to feel sick or light headed while working stop and get some fresh air.
The best way to spray paint with cans is to, hold the can about 10 inches from the subject and to make long even passes, also it is a good idea to go and do all the junctins of the frame tudes and the bottom bracket area first, as they are the hardest to get and easiest to get runs in if you over do it. Another good idea is to use many light coats instead of one or two heavy coats.
With the primer what you are attempting to do is cover the areas where you sanded alway rust and also to fill in and even out the light gouges and imperfections in the old, worn, paint so that you have a nice ever surface to paint on.
After priming I like to lightly sand the frame, with either 220 grit wet/dry, to keep the paper from clogging, or also a red scotch brite or 00 steel wool pads, which do not seem to have the clogging issue. This gives a real nice smooth surface for the paint to adhear to.