primer is a thick solid white paint like thing, it sticks to everything, and basicly just is like a new sheet to start painting
Not really. Primer is a paint that you can get in many different colors. For a bike, black, gray and white are all most need. It is used to fill the small chips and such before painting, and offer a smooth layer for the paint to stick to.
Also, the different colors lead to different finish colors.
Example: If you use a white primer, and then paint green over it. It will come out very bright green. HOWEVER, if you use black or gray, the green will come out dark. Pretty much 2-3 times darker. White is best when you want bright colors, and gray and black for dark(like say navy blue).
Is primer necessary? Or can you just sand the rim and put on the paint?
You can just sand and paint. But to make it last longer, and look better. Primer is the best way to go. It is only 2 extra coats of "paint" and then you paint will lay down nice and smooth.
im looking to repaint my profile hubs, any suggestion. a walk through tutorial would be great
Oven cleaner takes the color off Profiles. Take the hub apart, and spay it with extra strength easy off. Wait about 5 min, and use steelwool on it. That will take alot of. Redo it till all old color is gone. Then prime it (gray or white primer work best to make a color pop. Then use 2-3 light even coats of paint. Let about 1hr pass between coats. That way it will dry some. Then after the primer and paint is dry...hit it with 1-2 coats of a good clear (use matte if you dont want it super shiny or gloss if you want it to glisten). Then allow it all to dry 24-48hrs and your set.