Useful tips for pet portrait painting
Stretching your own canvas
When creating your pet portraits you can save money and get a better quality finish by preparing your own canvases. For general work go for a canvas weight of 10 oz, large works or works that will carry heavy amounts of paint will need to be heavier (12-14 oz). For stretcher bars the cheapest will be made from standard softwood, these are OK for small works. For better stability and long term use, go for stretchers that are kiln dried and preferably made from hardwoods.
I have seen examples of "how to stretch a canvas" on the web, and most fall short of ideal. This is how I do it.
1. Assemble the stretchers. This will give a template for the size of canvas you'll need.
2. Lay the assembled stretchers on the un-primed canvas and cut around it leaving around 3 inches extra all around (this is based on using stretcher bars that are approx. 18 mm deep). This can be roughly done at this stage.
3. Apply a coat of gesso to one side of the canvas using a palette knife to spread it around and a brush to smooth the finish. Canvas has a "front" and a "back", where the texture of the weave is different, choose the side which suits your painting best. It is also best to use an acrylic gesso, modern gesso is suitable for both oil and acrylic and a more flexible than traditional gesso. Once this is dry it is best, though not absolutely necessary, to coat the reverse with gesso as well. This will help protect the exposed canvas from moisture in the atmosphere and rotting it.
4. Once these first layers of gesso are dry place the stretchers back on the centre of the canvas and draw a straight line around it, this time leaving 2 inches of extra canvas around the frame (for 18 mm stretcher bars). When the outline is drawn you can cut the canvas along the lines so that you end up with nice straight edges and as we've cut into canvas that has been gessoed, will avoid fraying.
5. Lay the stretchers again on the trimmed canvas, as close to dead centre as possible. Start with one of the longest sides and fold the excess over the bar keeping it as tight as possible (without pulling the canvas over too much) and pin or stable it starting at the centre and working out to the corner keeping the canvas tight all the time.
6. Go to the opposite side and, starting at the centre using canvas pliers, pull the canvas tightly over the bar and pin or staple it to the edge whilst keeping it taught. Then go to each corner in turn, pulling the canvas over the bar and away from the centre to eliminate any creases, whilst pinning at end (but before the joint starts).
7. Go to the other sides and repeat the process.
8. The canvas can now be pinned to the back of the stretcher bars to keep the edges flat. Position each pin or staple between the position of the pins already on the sides. This helps spread the load.
9. As we have allowed only 2 inches of canvas around the frame, we do not have excessive material on the corners, making it easier to deal with. Working on each corner in turn, pull the corner of the canvas over the corner of the frame as tightly as possible, at the same time fold one side over the corner and the other side over the top of that so that the corner of the canvas is under the two sides and pin or stable the whole lot in place, keeping it taught all the time. Repeat for each corner.
10. Check the surface for any knots or imperfections in the canvas and if necessary these can be rubbed out carefully with a pumice stone or light sand paper. Once ready, apply an additional two or three coats of gesso to the face of the canvas and sides, allowing to dry between coats.
11. Once finished insert the corner wedges to help tighten the surface of the canvas.