Flat Brushes

• Flat brushes feature a flat ferule, and typically have bristles all of an equal length and cut flat across the end. This allows them to draw crisp, straight lines when loaded with paint. It also allows them to be useful to fill in large areas or shade in objects on your canvas. Occasionally you will see a flat brush with its bristles cut at an angle, with one side of the bristles considerably shorter than the other. This is useful in tight corners and detail work. Some artists will create their own angled flat brushes by trimming the bristles of an old square-bristled flat brush.
  
  

Round Brushes

• Round brushes have a round ferule, and bristles which are tapered to a point at the end. This point makes them useful for detail work, and poor for drawing straight lines, filling in large areas or shading. The round brush can be used in may areas where even a very small filbert or flat brush would be too large for fine detail work, and is therefore indispensable. The key to using a round brush is carefully load it with only the amount of paint necessary. A heavily loaded round brush tends to drip and spread paint inconsistently.
  
  

Filbert Brushes

• Filbert brushes are among the most useful type of brush for acrylic painting. Their flat ferule and round-ended bristles allow painters to fill in large areas evenly and consistently, paint crisp curved lines, and allow lines to taper to the end. The majority of most paintings are completed using a filbert brush. Used on its side, a filbert brush can also be useful in lettering and drawing thin, straight lines. Old filbert brushes are also often employed for techniques that require dry brushing.
  
  

Other Application Methods

• Depending on the thickness and viscosity of acrylic paint, sometimes other tools are used to apply it to a canvas. While not typically considered brushes to non-painters, these tools spread the paint and allow it to be molded into an image just like traditional paint brushes. The most popular of these alternative tools are painting knives and palette knives. Painting knives are plastic or metal knives designed to hold paint and spread it across a surface. Painting knives have a blade angled down from the handle, while palette knives are flat. Other artists prefer applying paint with cloth rags, string, a toothbrush or even their hands.