Re: small tear in my canvas
If the edges of the tear meet and there is not much fraying, simply glue a 2.5 cm square of fabric behind it, taking care to position the torn edges together. It would be best to place the canvas on a flat surface, and place a wax-paper-covered block of wood under the patch.
The patching fabric should be of the same material as the canvas: cotton or linen. Don't use polyester or silk.
Then cover the torn portion on the front with silicone release paper or with wax paper, place another flat block on it and then a nice, heavy tin of food or several heavy books. You have to make sure the torn section is neat and flat. Any wrinkles or overlaps will be set in the glue.
Let the glue set and dry.
When the glue is dry, use a couple layers of gesso, sanding it smooth between coats. You might want to coat an area all around the patch so that the final, small ultra-smooth gessoed area doesn't contrast too greatly with the canvas texture on the rest of the canvas.
If the fabric around the ripped area has stretched, you will have to bring the fabric back to its original woven shape. This might be the case if a small object, say a broom handle, has pushed into the canvas to the point where the fabric ripped. This can be tricky.
You might be able to find someone who could repair it for you for very little money. When I was a child, there were many neighborhood tailors who were adept at re-weaving. I still know of one near my house. Today, of course, most clothing is so cheap that you don't repair, you just throw it away.
If your rip is pushed out of shape (dented), perhaps there will be a tailor or clothes repair person near you who could bring the fabric back into its original shape.
Judging a Manet from the point of view of Bouguereau, the Manet has not been finished. Judging a Bouguereau from the point of view of Manet, the Bouguereau has not been begun.
--Robert Henri, The Art Spirit