Many different types of primer come packaged in aerosol spray cans. We have rust inhibitive products, bonding primers and stain sealers. These are excellent for difficult to paint and unevenly shaped surfaces. I find they work great for applying an even, thin film without brush strokes to things like lamps and outdoor furniture or decorations.
Remember to always flush out the nozzle by spraying the last few shots with the can inverted until the propellant blows through clear.