A stretcher bar is mainly used to create a wooden stretcher frame for paintings and canvas. Stretcher bars are generally wooden pieces that form a frame in which the artists mount their canvases. Owing to the same reason, stretcher bar is often termed as canvas bar as well. Canvas bars generally come in variety of sizes and dimensions catering all types of canvases. They are generally classified into three categories: small, medium and heavy duty stretcher bars. The bars are usually available in pairs and can be bought in boxes as well. Most commonly these bars are made out of fir wood and they resist distortion in their dimensions owing to changes in temperature and moisture of the surroundings. A heavier pine stretcher bar, though elegant in appearance and side profile, is more prone to distortion in its dimensions.
Heavy duty stretcher bars are the best for appearance owing to the highest side profile which is quiet characteristic to it. A stretcher bar can be easily assembled by anyone by simply following the instructions being provided in its manual. The canvas needs to be in a taut position and it may be quiet difficult to hold the canvas and staple it at the same time. For serving the purpose canvas pliers can be used to hold the fabric over stretcher bars while you can easily staple them with other hand. Special care must be taken that the canvas is never permanently fixed by the stretcher bars as there are likely chances for slight distortion in its dimensions due to temperature changes. A minute allowance is always provided for stretcher bars to compensate expansion and contraction due to varying temperature.
The procedure of setting a canvas within a canvas bar is quiet easy. The stretcher bars can be easily pushed together and it is required to be made sure that they are secure and the angles are precise. A T-square and measuring scale can be used to serve the purpose. The edges of the canvas leaving the bars are chopped off so that the canvas appears as a single piece within the canvas bar. It is recommended that stretcher bars are always set with prior assistance for first two or three times though it might appear a bit awkward.