Stretching Watercolour Paper
Get it right!
The purpose of stretching watercolour paper is to create a surface that will not buckle when you apply the watercolour medium to it. A flat painting surface allows for more control over the flow, especially with washes. It took an little investment in materials and experimenting to complete these steps successfully. There were numerous hurdles and continuous learning to get the process to work: the board used, the preferred tape, amount of water applied, and drying problems. For an ideal surface, as Alwyn Crawshaw says about correctly stretched paper: "It's heaven to paint on!"
Fig.1 Purchase a good quality piece or more of 1/2-inch plywood. Usually free of charge most lumber stores will cut them off from 2 feet by 4 feet or 4 feet by 8 feet sheets. 1/2-inch spruce plywood tends to warp making the process awkward so if you want something which will remain flat but a little pricier, purchase a 1/2 inch or 3/4 inch 8-ply birch plywood. You can also use hardboard/Masonite as well. For portability, I use a 1/2-inch birch ply that's cut to fit into my art bag. If your project employs a full-size piece of Arches 140 lb paper (30 inches by 22 inches), it helps to manage the space to have a 3-inch border around the paper. So, in this case, the plywood would be 36 inches by 28 inches. For a quarter sheet of paper (15 inches by 11 inches) plywood would be cut to 21 inches by 17 inches and so on. Applying finishes such as varnish or urethane to the surface causes the water to bead and the tape applied will not wet evenly so I suggest just sanding the board lightly and leave it raw.
Fig.2 Soak both sides of your watercolour paper in cold water for at least 10 minutes so there are no dry spots. Cold water is best as warmer water tends to remove the sizing. Sizing keeps the paint from blotting and will allow for brighter hues. Hold it by the edge letting any excess drip off.
Fig.3. Lay the paper (either side) on the plywood so that it is parallel and equidistant from all sides and smooth it down by hand removing any bubbles so it's nice and flat. Aligning the paper makes aligning the tapes easier. After some practice, you'll develop a good eye for this and make everything line up.
Fig.4 With your board laying on a horizontal table for even seepage take a small sponge (Dollar Store) and soak it in water moving it against the wood around the edge of the paper so that the surface is wet but not too wet. This is where you experiment with the amount of water you dispense and I suggest less is better. I found that a sopping wet surface causes the tape to eventually lift off when drying because the glue has washed away resulting in poor contact.
Fig.5 I was successful using a 1-3/8 inch 492-foot original butcher tape roll for 11-inch by 15-inch paper. I purchased a quantity of rolls from Pillar Tapes in Toronto. A wider tape (2 inches) might be better for larger sheets because of more paper area shrinking results in the more gluing area requirements.
Fig.6 Now that your paper lays flat and wet rip off suitable lengths of tape. I found it safer not to wet the tape because the glue tends to wash off easily. Place the dry tape glue-side down, so it's half on the paper and half on the wood. Smooth each piece of tape down with your fingers until all bubbles disappear and the tapes are snug against the paper and the wood. There might still be some buckling in the beginning, but this will disappear when drying and stretching are complete. As you experiment some areas will not adhere so you may decide to follow up with an ordinary office stapler before drying is complete. Still not satisfied? Then start over with the same paper by rewetting it again following the steps above.
Fig.7 Keep it neat by cutting off any excess tape at the corners with a razor knife.
Fig.8 Do not apply any heat or fanning but let it dry on its own in your room. The speed of drying will depend on temperature and humidity. Stretching your paper can be a part of the creative process that goes into the painting. Besides, it's a lot cheaper than relying solely on 300 lb. paper or a block of paper that you don't have to stretch.
Fig.9 Remove the tapes by patiently soaking them with warm water using the sponge.
Fig.10 I store watercolour works between two layers of hardboard cut to appropriate sizes clamping with bulldog clips (Staples). A flat watercolour facilitates easy framing. Good Luck. !