Surface Preparation of Canvas

Canvas is available in two forms, gessoed or pre-sized and ungessoed. Pre-sized, usually with gesso (acrylic medium combined with white pigment – very opaque, flexible and non-yellowing) and coated with a layer of white acrylic paint. The second is unsized, or ungessoed, canvas ready for surface preparation. Either you choose is available in many widths and textures. Many artists buy the sized and coated canvas (pre-stretched or by the roll), but then put on additional layers to further seal the fabric weave. Unsized canvas should be primed in all painting applications except acrylic staining, in which the canvas is purposefully left open and absorbent.

There are several techniques for surface preparation when dealing with canvas. If the canvas is already pre-primed with gesso and/or acrylic pigment, additional layers of gesso might be added to create a smoother and more even base upon which to paint. If you prefer an extra smooth finish, apply gesso over the pre-stretched canvas surface, making strokes in one direction. Allow it to dry thoroughly, and then apply a second coat in the opposing direction. If you use a soft brush, smoothing out obvious brush strokes as you apply the gesso, your finished product will be fairly smooth. But, if extra smoothness is desired, sand the surface lightly with light-grit sandpaper to remove any irregularities in the surface; then clean away dust with a soft cloth. If further smoothing is necessary, sand with sandpaper that is even finer.

Extra smooth finishes can be obtained by repeating the steps above. After the third or forth coat, begin to use finer and finer sandpaper, along with water, to polish the surface to a near glass-like finish. It can take up to eight coatings and sandings to achieve the extra-smooth finish loved by many fine detail artists who consider the effort well worth their time.

Raw canvas intended for use with oils should be sized with at least four coats of gesso. For use with acrylics in all techniques but staining, sizing (gesso, etc.) is also necessary. Application of the first layer could be done with a wide putty knife. The blade will smooth the gesso over the surface and work it into the weave of the fabric. Attempt to apply the gesso smoothly with the blade, avoiding ridges and oozes. After this coat dries, sand it lightly with medium sandpaper and clean with a cloth to remove the dust. Repeat the application/sanding process for two additional layers. Clean any dust from the surface and it is ready.
Although there is added effort involved in the preparation of unsized canvas, it is available in weights heavier than pre-stretched/sized canvas. This is especially helpful when the works are large. Thicker canvas stretches tighter for a smoother, more professional presentation and will not relax over time.

A further advantage to sizing your own raw canvas or resurfacing a pre-sized canvas is that you can augment the texture on the surface. If you want to create an impasto look, you can apply gesso thickly and build a surface. With thick, visible texture, less paint yields a richly applied painterly surface. You can also press textures into a thick, wet layer of gesso for unique textures. Some tools that are used for this method of surface preparation include crushed kraft paper to yield a broken, uneven, crackle-type surface; knife blades to create ridges and lines; and sponges to create a uniform but not smooth surface. Adding material such as sand, small stones or gravel, grasses, small twigs and the like to a layer of gesso can create some wildly textured surfaces that are unique.

Consider how fortunate we are to be able to pop into any art supply center and purchase acrylic gesso. The old masters were forced to create their own canvas preparation material. The ordeal began by melting animal hide glue (an organic product that turns rancid easily) and then combining it with powdered white pigment. This concoction was cooked in a double boiler until melted and well blended and then applied to the surface while still hot. It could only be used on wood or other rigid backings, as any flexible surface like canvas would allow the brittle surface to crack or break and fall away.

Hide glue surfaces cannot endure any blows or hard treatment and must be handled carefully. Despite all of these challenges, modern painters have begun a renaissance of this surface treatment method. Technique purists and oil painters that are trying to reproduce the look of old works are especially fond of the surface–purists because it hearkens back to the period of the masters and historical painters because of the “easy to age” surface. Today, paintings can be created that have the look of centuries-old pieces.

So if you paint on canvas (or canvas boards or Masonite), there is a surfacing method that could add new dimension to your work. Perhaps you are ready to add thick textures in the surface preparation. Perhaps you want to paint on an extra smooth, slick surface where every brush mark can be blended to perfection. Or maybe you want to begin to work on a new grand scale and want to know how to surface your own canvas. With today’s materials, there is a preparation method exactly suited to your needs that makes it easier and faster than ever.

Gallery Wrapped Stretched Canvas

Materials:

Canvas – Duck canvas or linen, (unprimed)
Stretcher bars – Or 1” x 2” pine
Staples or tacks –To attach canvas to stretchers
Staple gun – Type found in hardware departments
Hammer – Helps to make precut stretchers square and to tap in any staples that need it.
Square – L shaped, metal preferred
Sewing Scissors – be sure they are sharp!
Gesso – As a sealer/primer to be used on the canvas surface
Miter saw – Necessary to cut stretchers at a 45 degree angle. Box is less expensive and will work, but if you can afford it an electric miter saw is a wonderful time and energy saver.
Nail Punch – Optional – used to help make staples flush to wood in corners
1- ½” Nails – Optional – used to make corners more secure
2” Paint Brush

Sources for Materials

Dick Blick – www.dickblick.com
Michaels
Sax Arts and Crafts
Home Depot
Wal-Mart
Ben Franklin

Creating a Stretched Canvas

Choose size desired for a finished canvas. Keep in mind if you want to frame it with a standard size frame, you will want to go with sizes easily available. 5” x 7’, 8” x 10”, 11” x 14”, 12” x 16’, and 18” x 24”, anything larger would likely need to be specially made. You will find most commercial framers are willing to work with just about any size of canvas you wish to frame. But if in doubt, inquire with your framer.

If you are cutting your own 1”x 2”s, inspect them before purchase for bowing and/or excessive knotting. 1” x 2” usually comes in a length of ten feet. Most lumber yards will cut them down to a smaller size if it works better for you to handle. Some will go so far as to cut the 45 degree corners for you to length. But since this is ground for your art work, you will probably prefer to cut your own, to ensure a tight fit and correct size.

Once home simply cut the ends to meet in a 45 degree angle. Be sure to keep in mind the end measurement of your canvas will equal the longest edge of the corner when assembled.

How you actually attach your corners will depend if you purchased, or cut your own. ** See below if you have purchased your bars.

Lay the large metal square down on a flat surface. On the inside corner of the square lay down the stretcher bars against the edge. Lay down all four edges to be sure they are the right size, and double check for warping of wood and other imperfections. If they aren’t this is the time to make adjustments, not after they are attached to each other.

Before attaching to each other, BE SURE THEY ARE SQUARE! It works best to worry only about 2 pieces at a time, at this point. So remove two of the bars and concern yourself with just what is happening in the corner of the square

If you have cut your own, it works well to simple staple them together on both side. It is usually a good idea to put at least 2-3 lined up in a row.


Be sure that they are flush as possible with the surface of the wood. If not they will create a ‘bump’ on the canvas that is not a desirable end result. To do this tap with a hammer or use a nail punch. Be sure to recheck that things are still good and square. Turn over carefully and do the same process to the other side. Be careful when turning over that you do not cause the first staples to come out or twist. It is important to do both sides, so that there is adequate reinforcement.

When all four sides are connected, ensure they all are square with each other, an old carpenters trick is to simply measure from corner to corner crosswise, if they measure the same than they are still square.

**If you have purchased your stretcher bars they more than likely have tongue and groove ends. These ends will fit into each other and create 4-90 degree corners. Simply tap or push the ends into each other until tight and square. Your purchased bars also come with small pieces of wood called ‘keys’. These are pushed into the openings in the inside corners to help make it tighter and more stable. Some artist will also tap in a small nail, or staple the corners to ensure they do not move when stretching canvas on them.


Lay your canvas material onto a clean flat surface. Laying the stretcher bars on top, and measure around the stretcher bars about 3 inches of extra material on each side.

Starting on one edge fold the fabric up and over the edge of the stretcher bar, staple the canvas to the bar in the center.


Pull the canvas snug and repeat on the opposite side. Repeat on the remaining two sides. Be sure to pull canvas snug each time, before it is stapled.


Starting on the edge you began with. Place staples approximately 2” apart all the way around, except for the very corners. Then do this on all four sides.


There are several ways one can create a corner that will work for various needs. Our goal is to create one that will work for a professional looking corner, with or without a frame. If done correctly, you can paint around the sides of the canvas and hang it without a frame and it will appear professional, with very clean lines. No matter what style of painting you may have.

It may take some practice to get the hang of folding the corners and have a smooth edge. But take your time; it is well worth it in the end.

*Preparing to fold corner
*Folding corner
*Folded corner

*Folded corner from side

*Corner folded and snug, stapled down.

Priming Canvas

NOTE: If you use pre-primed canvas the following is not necessary.

Lay down your stretched canvas painting side up. Wipe away any stray threads or dust that may have attached them selves when stretching. If necessary use a damp cloth.

Going in one direction and using your 2” brush apply gesso to the surface. Be sure to paint the edges of the canvas also! Allow this first coat to dry thoroughly.

You can leave the canvas as it is for a slightly rough tooth surface, which works well for general use. Or if you want a rougher surface to paint you can add pumice, marble dust, sand, or about any other materials to the next coat to increase the surface tension. If you want a smooth surface, take fine sand paper and lightly sand the surface between coats of gesso.  Allowing the gesso to dry well each time.

Tip: Apply 1-2 more coats depending upon surface desired. Be sure to go a different direct for each coat of gesso. This will help to build a stronger and longer lasting surface.

*TIP – If you used cotton duck canvas and find a ‘dent’ anywhere on your canvas wish you can fix this with a spray of water on the back side of your canvas. Allow the water to dry and the canvas will stretch back into its original shape. If you did not use Duck canvas and find yourself in a similar situation, there are more high tech materials on the market, than our use of a water bottle. How you handle the situation depends on the materials used. We suggest you check with your art material supplier for products available and their use.

Part Four – Facial Proportions

Part Three – Palettes

Part Two –  Mediums

Part One – Materials

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