Using the correct roller can significantly improve the quality and reduce the time spent on your next painting project. The right roller will provide a better finish on the wall as well as reduce clean up time. When most people begin a painting project, they select the generic rollers that you can find at all big-box hardware stores. These rollers are often the cheaper option however the result is a lot of extra work and a cheaper looking finish.
Rollers are available in a variety of sizes so make sure you are picking a size that is consistent with the scope of the work that you are doing. Rollers and roller covers are also available in many different materials from sheepskin to foam. The surface you are painting will determine the correct thickness of nap of the roller to use.
If doing a ceiling surface or painting with a low-sheen or flat paint, a higher nap roller will give you the best finish. Smaller or lower-nap rollers are used for paints with a higher sheen level as these kinds of rollers will provide you with a smoother finish. Normally, a roller with a 13-15mm nap is ideal walls while an 18mm nap roller is best for ceilings.