At first sight painting a part from an aerosol can looks very easy. It really is, but there are still rules to follow here.
Shake the can
Shake the can thoroughly for a few minutes before painting, so that all the components mix and the contents of the can become uniform. Skip this and the result may differ greatly from what you expect. The color, for example, may not match the one on the label, because pigments of different colors separated during storage and were not mixed again, so only one of them is sprayed. The metal mixing balls inside paint cans are there exactly for this.
Keep the right distance
While painting, the distance from the can to the surface has to stay within 25–30 centimeters (10–12 in.). That is roughly the height of two cans without their caps.
Spray from closer than that and runs are very likely.
Spray from farther away and almost all the solvent evaporates in flight, so the paint lands on the surface as dry overspray.
Do not linger, or you will get runs
For the paint to lay down evenly, apply it with quick, steady passes, starting and finishing each pass beyond the edges of the area being painted. Otherwise runs form wherever the can stops and the paint lies unevenly.
Cross the coats
If you are painting in several coats, it is best to apply each coat at right angles to the previous one: one coat with horizontal passes, the next with vertical ones. The film then comes out more even.
A thick coat means a risk of runs
Two thin coats with the intercoat drying time observed are better than one thick one: thin coats dry faster and the risk of runs is lower.
Clear the spray tip
To keep the spray tip from clogging, clear it right after use: turn the can upside down and spray until nothing more comes out. What has to stop coming out is the paint, not the propellant!
