Paintings are the oldest form of artistic expression. Many people consider paintings as being the ultimate form of art. The main ingredient in a painting is the artist's input. The degree of talent and the vision of the artist will define how you, the viewer, respond to it.

A painting can be done in oils or in acrylics. Acrylic paints are new to the beginning of the last century. Paintings in oil are still considered to be the best, but paintings done in acrylics have proven the test of time and many excellent painters use acrylics for their artwork. Both oil paintings and paintings in acrylics are in museum throughout the world.

A painting can be done on any surface, but the best known surfaces are canvas. Canvas can be made of woven cotton or linen. The canvas is surface treated with gesso to seal the fibres and thus hold the paint. There are, of course, different quality grades of canvas. The material is usually stretched on stretchers that have corner wedges that help tighten the painting. Since canvas is a usually a natural material, it responds to changes in temperature and humidity and at times appears more loose or tight on the stretcher. The stretcher should be thick enough to support the painting so that it remains flat and doesn't warp. Paintings larger than 24" x 30" usually need cross bars to keep the stretcher rigid.

There are five dimensions that need to be considered when measuring a painting for framing. They are the outside size, the diagonal size, the sight size, the rabbet size and the depth of the art.

• The outside size represents the actual size of the painting. In the industry, we generally mention the height before the width. This is the method used regardless of whether the painting is horizontal or vertical. Pay attention to the corners. They often extend beyond the size of the sides.

• By measuring the painting on the diagonal from the corners of the canvas you can determine if the painting is out of square. This is important because if it is out of square we have to allow for extra rabbet space to accommodate it.

• The sight size is what you will literally see of the painting when it is framed. The painting can be framed inside a frame where you would cover about ¼" on each side or as a float where you see the whole canvas.

• The rabbet size is the size of the channel in the frame's inner edge. This is where the painting fits. If the painting is out of square, we can adjust the rabbet width so that the painting will fit properly.

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