Before using a canvas one must make sure that the canvas is adequately stretched. It may be easier to use a canvas that is pre-stretched and make sure to unwrap the plastic wrapper around the canvas before setting it up. The next step in preparing your canvas to paint is using a primer. This is usually achieved by applying a substance called gesso and it comes in three varieties - oil paint, acrylic and tempera. Similar to using a primer before applying paint on the walls of a house or room, a primer protects the fibres of the canvas and makes what you paint archival while making the surface easier to work with. Primers also help painters use less paint in creating their artwork as the canvas is less likely to absorb most of the colours and the primer also protects the brushes one uses.