A stretched canvas can be very expensive depending on the brand, size, whether or not it is gallery wrapped, and quality. Sometimes stretching the canvas yourself is the cheapest route, but not always. This guide will cover various aspects of stretched canvas, and how and when to stretch your own canvas.

Stretched Canvas Attributes

• Types of Canvas: Canvas is the cloth that is stretched over the wooden bars (the stretchers). Linen is also sometimes used instead of canvas. Fine weave canvas is great for painting people and very detailed paintings. Canvas that has a grain such as regular canvas is best for a variety of techniques from impasto, impressionism, and portraits. There are no clear advantages between the two types except with personal preference. Various canvases also differ in weight and weave. Some people prefer the expensive, heavy canvas for their paintings, but this is not necessary. My teacher at my old high school used to stretch canvas for a company and said the cheap canvas found at local department stores works just fine.
  
• Primed vs. Unprimed: If a canvas is primed, it has at least one coat of latex painted on it to help protect the canvas. If you are planning to use oil paints on the canvas, it is essential that the canvas is primed. Oil paints will eat through the canvas if is no protected by latex. The canvas does not have to be primed if you are painting with acrylics, but raw canvas will eat up the paint more and make watered paint bleed. Some canvases have been primed several times. The more times the canvas is primed the better, but be careful. There are various grades of latex. Gesso is one of the most common latex used for canvas. Some gesso cover canvas better than others. Basically, more layers of gesso does not always mean a better canvas. Latex paint used for houses may also be used to prime canvas. I've seen it used as a cheap substitute in classroom studios.
  

• Stretchers: The stretchers make the wood frame that the canvas is stretched over. Thicker stretchers are always better. Thin stretchers that are under and inch thick can warp easily. Small canvases rarely have this problem, but anything 30" by 40" or bigger will start to warp. I suggest buying large canvases with stretchers at least 1.5" thick to prevent this problem. Some canvases have stretchers 3" thick. These are often called box, or 3D canvas.

  

  Stretchers this thick aren't necessary, but it is fun to paint the sides. Another important thing about the stretchers is if the canvas has any crossbars to give it support. Crossbars are not necessary for canvases smaller than 30" by 40", but it is a must for large canvases. Some people use regular wood boards for the stretchers of the canvas. This is fine, but it can lead to one major problem. Regular wood boards do not have the angled edges like stretchers do. These angles in the stretchers keep the canvas from rubbing up against the wood while painting. Painting with a canvas stretched over normal wood boards can leave lines on the edges caused by the brush pushing the canvas up against the edge of the board.

• Gallery Wrap: Traditionally wrapped canvases have staples visible on the sides. Gallery wrapped canvases, though, have the staples hidden from view. I highly advise people who are planning to sell their artwork or put it in a gallery to use gallery wrapped canvases. If the stretched canvas has staples visible, it must be framed before it can go into most galleries.

  

• Boards vs. Stretched: Canvas boards are definitely not the best surface to paint on. Unlike stretched canvas, boards warp very easily. It can be difficult to keep the board from bending. Many art professors will not allow boards into the classroom because of this.

When to Buy Stretched Canvas -

If you plan to paint several paintings the same size, then I highly suggest buy stretched canvas in bulk. Normally, a 30" by 40" stretched canvas at the store is $40, but it is bought in a lot, it may only be $30 or even $20. This is the most cost effective and timesaving route. If you plan to paint several paintings of different size, it may be cheaper to stretch your own canvases. Small canvases are still pretty cheap if bought in singles, but large canvases are very expensive. If you plan to paint a huge painting (bigger than 36" by 48") then it is almost a must to stretch your own canvas unless you are wealthy. Any canvas bigger than 36" by 48" has to be shipped by freight. Stretching your own giant canvases will save you lots of money.

How to Stretch Your Own Canvas

Stretching your own canvas is very simple thing to do. You only need a few supplies to do this successfully even for large canvases.

Supplies:

• 4 stretchers (and crossbars if necessary)
• hammer
• staple gun
• wood glue
• canvas (or linen)

Optional:

• canvas pliers
• primer
• nail gun

1. Clean off your work area and gather all of your supplies. It is best to do this on a large, flat surface.
2. If you have crossbars, glue those together by putting wood glue in their notches if they have any. Make sure they are perpendicular. Get the staple gun out and staple them together after the glue has dried.
   
3. Put wood glue one the edges of the first two stretchers bars to be put together. Then, using your hands, slide the together. If they are moving very slowly, be patient.
4. If you have crossbars, put glue on the ends of them all. The push the two stretcher bars you have slipped together up against it. Make sure the tabs of the crossbars go under the edge of the stretchers.
5. Now glue the other two ends of the stretcher and start slipping the other stretcher bar against it.
6. After you have the three stretcher bars together, slip in the last one. Be sure the crossbars are in the right place in the middle. You may have to use a hammer to push it into place. Be careful not the split the wood with it though.
7. Hammer all of the edges until all of the edges of the stretcher bars have no gaps in between their edges. After this, staple the crossbars to the stretcher bars and put nails in the corners of the stretcher if you have any.
8. To make sure the stretcher has straight edges, push it into a corner such as that found in a doorway. Push the edges so they line up with the edges of the doorway. Do this to all sides, then let it dry over night.
9. After the stretcher has dried, cut out a piece of canvas has three to six extra inches on each side of the stretcher.
10. Get out the staple gun and the canvas pliers. Staple the piece of canvas on the back of the stretcher. Continue to this with the rest of the canvas. Be sure to pull the canvas tightly before you put in the staples so that the canvas does not flop around. The canvas pliers make it easier to stretch the canvas tightly over the stretcher. This can be done by hand, but you need a strong grip. To stretch huge canvases, you will need to use your body's weight to stretch the canvas tight enough.
    
11. After the canvas is stretched, then paint the primer on top of it if necessary. Paint at least two coats of primer. The more the better.
12. After the primer has dried for a day, you may no start painting on your canvas.

Stretcher bar kits can be found on eBay, which makes stretching your own canvas much easier since you don't have to do any math. It is also usually much cheaper to buy stretcher bars on eBay then from direct supplies since they sometimes have extra charges for making notches in crossbars. Stretching your own canvas is something that shouldn't ever intimidate you, no matter what the size.