Since most wall paints are formulated for roller application, the average do-it-yourselfer can paint faster and smoother using a roller. Standard rollers are 7 to 12 inches wide, but they come in lengths from 2 to 18 inches. Special rollers are used for painting round surfaces or into corners. The best frames are made from heavy-gauge wire, have end bearings for smooth operation and a threaded handle for extenders.
Just Roll With It
Critical elements in any roller are the type of fiber used and length of the nap. Mohair covers are good for enamel: lamb's wool is excellent for alkyd paints, but not latex. Synthetic fibers make all-purpose covers but cannot be used with specialty coatings, such as epoxies and polyurethane.
Smooth surfaces such as plaster and hardboard, require one-fourth-inch or shorter nap. Very short nap is used with enamels and gloss finishes. while longer naps are used for latex or flat paints. Naps of three-eighths to one-half inch are used on semi-rough surfaces, such as light stucco or sandblasted metal. Rough surfaces, like concrete block or heavy stucco, require naps three-fourths of an inch to 1-1/4 inches.
Quality aspects of any roller are the type and density of its fibers. The density of the fiber determines the roller's ability to hold paint and spread evenly. Inexpensive rollers lose resiliency, become matted or fail to spread paint and produce a mottled finish. They may also leave lint behind.
Core construction is also important. A quality roller has a round core with no conspicuous seams. It shows no indication that the fabric will separate from the core at the ends and does not deform when squeezed gently. Some cores are made of untreated cardboard, which will soften and collapse from excess moisture: phenolic (treated cardboard) and plastic hold up in heavy service.
You can extend the life of your roller with proper care. Clean your roller after every use. Remove excess paint by pressing the roller on newspaper, then wash in solvent or water. After it has dried, wrap it up before storing.