A paint brush consists of three parts - bristles, handle and a metal band called a ferrule that holds the two together.
The bristles are set in a block of solid resin to keep them together, and are either natural bristles (hog is best) or synthetic fibres.
Look for Bristles that taper from a thick base where they are attached firmly, down to the narrower tips, giving the brush flexibility. Well-tapered bristles are a sign of a quality brush. Avoid brushes with bristles that are all the same.
Cheap brushes have fairly short bristles that are often packed out with a wedge in the center to make them appear thicker. This means they don't hold paint particularly well and the short bristles can tend to leave brush marks.
Quality brushes have longer bristles and more of them so they hold more paint and give a smooth finish, free from brush marks as the bristles are 'laid off' - drawn lightly over the finished paint. They are ideal if you want a fine finish, especially with gloss paints and varnishes
The handle may be wood with a lacquer or varnish finish, or plastic. Unfinished wood handles are a professionals choice as they do not slip and turn in your hand providing a much better grip.
As a general rule, use bristle brushes with oil-based paint.
Natural China (hog-hair) brushes are the best. Never use natural-bristle brushes with water or water-based (latex) paints, the bristles absorb water, swell up and become unruly.
Nylon and polyester brushes are best for use with water-based paints and other products, as the fibres don't absorb water and will therefore not flare out.
Brushes come in many sizes and shapes. In general, brushes 3” to 5” in width are used for walls and large surfaces. Use smaller sash/angular brushes for furniture, windows and trimwork and for smaller wall spaces near corners, windows and doors.
If you invest in a quality brush clean it carefully after each use. A good brush improves with age.
If you prefer, you can buy cheap brushes and throw them away when you've finished if you're happy with their slightly inferior performance.
Proper Cleaning of Brushes and Rollers
When covering large areas, such as walls or ceilings, rollers are the best tool to use. Choosing the best roller cover for the job is important. Cheap roller covers ( polyester) tend to spatter more and drop pieces of fuzz and lint into your paint. Lambswools is the best you can get, they hold a large amount of paint, rarely leave "track marks" and do not splatter as much.
For enamel work such as painting doors, kitchen walls etc, use mohair covers.
Match the roller cover nap size to your job, the thickness depends on the surface being painted, the paint being used and the desired effect.
Use a thin roller cover (with less than ¼” nap) for gloss and semi-gloss finishes on smooth surfaces, such as plaster, floors and some walls.
Use roller covers approximately 3/8” to 1” thick when applying flat paints on medium-smooth surfaces such as most interior walls, concrete block, stucco and sandy-textured surfaces.
Special types of rollers
Corner rollers – ideal for corners and siding strips
Trim Roller – 3-inch size is ideal for cramped spaces
Radiator Rollers – 3/4" in Dia., perfect for behind radiators, toilets and water heaters.
Specialized roller covers exist for painting columns, pipes and other round architectural features
Foam roller – best for handrails and wrought iron.
Compression-type roller handles work best offering improved rolling and durability. These are the ones with 3-5 heavy wires between the ends, as you slide the cover on the wires are compressed securing the cover firmly in place.
Avoid inexpensive roller handles that feature a wing-nut for holding the roller on its cage.