Rollers are efficient tools for covering broad surfaces. Roller covers vary in length from 3 inches up to 18 inches. The normal paint roller nap varies from 1/8 inch to ½ inch. The longer naps hold more paint, but will also leave more roller tracks. For gloss/semi gloss finishes, lower nap rollers work best. Shorter - 3 or 4 inch rollers - work great on doors). For flat paints, a thicker, fluffier roller will hold more paint, drip less, and will apply the paint thicker and smoother.
Specially rollers are also available. These include textured rollers, particular good with textured paints, stipple rollers, rollers to paint uneven surfaces such as popcorn ceilings and long nap rollers (up to ¾ inch) for deck and driveway coatings. Visiting the website of the more prominent manufacturers of rollers and brushes will give you even more detail.
Before starting, be sure the roller cover fits snugly on the cage of the roller handle. If loose, the spokes of the cage can be pulled slightly apart for a tighter fit. Roller pan liners are a great idea. They cost less than $1 each, and make clean up much easier. After lining the roller pan; fill approximately half full with paint.
Extension handles are a great assets when rolling ceilings or high walls in stairwells. With many new home having two story foyers, families rooms etc, 18 – 25 foot extension poles are now available at your paint store or home center.