A good quality watercolor paper is made of cotton or rag fibers. Like all cotton items, the paper has a tendency to shrink. The paper absorbs water when you apply the paint, but as the paint starts to dry the paper will begin to buckle. This occurs because the paper is shrinking in an uneven fashion; only in areas were you have wet it by applying paint.
Stretch for Painting Ease
You want to keep your paper as smooth and flat as possible while you are working on it so that your pigment does not pool in low spots. If this happens you will not be able to make an even wash of color. The pigment will settle in the low areas creating dark patches, and will drain off of high areas creating light patches and visible backruns.
Have the Proper Materials
Stretching the paper, by attaching it to a piece of Gatorboard prior to painting, allows it to shrink more evenly. Gatorboard is made for this purpose and can be purchased at most art supply stores. It is comprised of foam sandwiched between two hard plastic-like sheets, which are moisture-resistant. Lightweight and re-usable, it’s a great choice for any watercolorist.
Attaching your Paper to the Gatorboard
You will need a regular household stapler, water, and a large flat brush.
- Make sure your sheet of Gatorboard is at least an inch wider than your paper on all four sides.
- Thoroughly wet your watercolor paper on both sides with your large brush and center it on your Gatorboard. The brushing action can aid in evening out the sizing on the paper. Some papers perform better if they are soaked, completely submerged in a tub or vat, for about five minutes in lieu of being brushed down.
- Once the paper is centered, staple it to the board. Staples seem to work best if placed every two inches or so all around the perimeter of the paper, parallel to the edge. Make sure to staple at least 3/16 of an inch in from the edge. As the paper dries it will make its initial shrink and pull tightly against the staples. If you staple too close to the edge the paper will tear completely away from the staples. The paper will start to buckle as you are completing this process, which is to be expected.
- Allow the paper to dry completely, overnight is best, before drawing or painting on it. It should be perfectly flat and smooth when dry.
You will need to work on the paper while it is attached to the board. If you remove it, it will no longer be stretched. The paper will expand and contract as it absorbs water and the water evaporates. If work with a lot of water, or paint wet-into-wet, the paper will buckle slightly while painting, but will dry flat.
You can tape off an area to paint, but keep in mind that it is difficult to tape squarely. Even if you manage to make it square, the paper may shrink some here and there as you paint and it can look a bit off. Sometimes it is best to just paint all the way to the edge right over the staples, keeping in mind that the edges may be covered by a matt later.
Finishing Up
When your painting is complete, allow the paper to flatten and dry completely before removing it from the board. Use a palette knife, spatula, or credit card to gently lift the staples, working between the board and the paper. The staples should lift with ease. The Gatorboard can be used again and again.
Your finished work should be smooth and flat. When framing, you will want to have a matt cut to cover the staple holes.
