To stretch a canvas for painting you should have the following:
- Stretcher Bars-wooden slats that are made to fit together. Each stretcher bar is one side of the canvas. Premade stretcher bars are available or you can make your own.
- Fasteners-staples or thumbtacks can be used to hold the canvas into place. Brass upholstery tacks were commonly used because they do not corrode. Staples are easy to put in place and easy to remove later.
- Canvas-either cotton duck or linen make best surfaces. Strong material is needed because the fabric is under great tension.
1. Slide mitred edges of four stretcher bars together. Make sure that you have two of each size stretcher bar. Check square by measuring corner to corner, then repeat for the other two corners. Adjust frame until both measurements are the same distance. Staple into place on both sides of stretcher frame. Do not glue or use other adhesives, unless your stretcher bars have no slots, because they can cause discoloration of the canvas and stretchers can be reused.
2. Cut canvas so that it is at least 3" longer on all sides. This will allow you to wrap the canvas around to the back obscuring your staples.
3. Pull tightly and staple canvas at four opposite points in the middle of each stretcher bar. Hold as tightly as possible for good tension. A canvas pliers can be used to help gain a strong grip. Work outward from each of these centers. Stretch evenly by moving from side to side and from top to bottom in an even pace. Only add a staple or two on the left and on the right of center for each, working toward the corners.
4. When you reach the corners, staple and tighten until the ripples are all gone from front of the canvas. If not, repeat process making sure to work evenly out from each center while moving around the canvas. When corners are tight take remaining canvas, crease it, fold it back, and staple tightly in back. Cleanly secure rest of canvas. Now you are ready for the surface preparation.
HINT: Before putting on painting ground, check to see if the canvas is warped. This can occur when stretching is uneven.