Stretch Watercolor Paper
Advice concerning stretching watercolor paper varies widely. Some advise stretching all paper under 300 lb., while others never stretch their paper regardless of the weight. A few even stretch paintings only after they are completed and considered successful enough to be framed.
Watercolor paper that is lighter than 300lb. will buckle or cockle when exposed to large amounts of water. The irregular hills and valleys that are created make it difficult to create a smooth, even wash, because the paint runs down into the valleys. In addition, the warped paper makes mounting and framing difficult.
There are several options you can choose from when dealing with this characteristic of water-soaked, light-weight paper. You can accept the natural warping of the paper and the resulting unevenness and banding of washes into your personal style. You can paint with less water so that the paper won't buckle. You can work on small areas of the paper at a time. You can avoid the problem all together by painting on surfaces that don't cockle when wet: 300lb paper, watercolor board, Strathmore Aquarius II paper, a watercolor block, or a synthetic paper such as Yupo. (If you paint on a watercolor block, you must wait until your painting dries completely before removing it from the block. If you remove it before it is dry, the paper will cockle.)
Finally, you can avoid stretching by gluing a piece of watercolor paper to illustration board. Cut the illustration board to the size of the final painting. Cut the watercolor paper slightly larger than the illustration board on all sides. Apply acid-free glue (Daige, Rollataq adhesive for permanent mounting) to the illustration board with a foam brush. Place the watercolor paper face down on a clean table, and place the illustration board on top of it glue-side down. Place books or some other heavy object on top until the glue dries. Trim off the excess watercolor paper.
Or you can stretch the light-weight paper to make it remain flat.
All methods of stretching involve soaking the paper until it expands and attaching the wet paper to a support to dry using one of several methods.
Note: Don't be concerned if the paper appears to warp during the early drying out stages. When it is fully dried, it will be drum-tight and ready to receive very wet washes.
The normal procedures for stretching paper produce watercolors with distinctive qualities. Because the surface sizing is softened, paints soak into the paper more easily, and washes can be laid down more evenly.
Soak Your Paper
Before soaking your paper, identify the side you will be painting on and mark it with a small pencil X in one of the corners.
Gently submerge the paper in a children's wading pool, bathtub, sink, tub, or tray filled with room temperature water. Soak 90lb paper for 5 minutes and 140lb paper for 10 to 15 minutes. Turn the paper over once or twice during that time.
The fibers in the paper will expand and some of the sizing will dissolve.
The key to stretching paper successfully is soaking the paper just long enough to get the desired results, and no longer. The paper has to soak long enough to absorb water and expand enough that when it dries it will tighten and create a taut surface.
The longer you soak the paper, the more it absorbs water and expands, and the more the sizing is dissolved.
If the paper soaks too long, it will absorb so much water and expand so far that when it begins to dry out and shrink back to its original size, it will create a tremendous tension capable of tearing the paper, pulling out the fasteners, or buckling the stretching board. In addition, prolonged soaking will dissolve so much sizing that your paper will soak up paint like a blotter.
On the other hand, if the paper is not soaked long enough, it will not tighten when it dries.
Unfortunately, advice for the proper amount of time ranges from 5 minutes to an hour, so you will have to experiment with your particular brand and weight of paper. (I soak Arches 140lb cold-pressed paper for 10-15 minutes.)
Some suggest periodically testing the paper while it is soaking. when it is ready, take it out.
To test the wet paper, hold it upright and bend one of the top corners toward you. If the corner springs back to the upright position, the sheet is not wet enough. If it's soggy enough to bend over under its own weight, then the paper is too saturated. If the corner remains where you bent it or very slowly returns to the upright position, then it has absorbed the right amount of water.
If it needs to soak longer, put it back in the water for a few more minutes.
When you have determined that the paper has soaked long enough, lift the paper out of the water. Hold it in the air by the two top corners until the excess surface water has dripped off. Then place the paper on a support board.
Allow a few minute for the moisture to even out.
If there are air bubbles underneath the paper, use a damp sponge or a two inch wash brush dipped in water to brush the bubbles out. Move the brush from the middle of the paper toward the edge.
Note: An alternative to soaking the paper in a tub is to apply water evenly over the paper with a sponge or flat brush and then cover the paper with a damp cloth and let sit for a while.
Choose a method of attaching the paper to a support.
Attach with Surface Tension of Water
Press the paper, right side up, against a smooth, nonabsorbent board (gator board, plywood sealed with varnish or a piece of plexiglas). The surface tension of the wet paper will cause it to remain fixed to the board for 5 to 10 minutes before it will need to be rewet. When you have finished the wet-in-wet portion of the painting, clip the edges of the sheet using large "bull dog" clamps. The paper may cockle somewhat, but it will not be a problem now that you've moved on to more detailed work that requires less moisture.
If the "bull dog" clamps are so strong that they damage the soft, wet paper, insert something between the paper and the clip (tongue depressor, popsicle stick, or a piece of cardboard).
Attach with Staples
Smooth the soaked watercolor paper, right side up, onto gator board, sealed Homasote board, or plywood. Using a regular household stapler and 1/4" staples, place a staple at the center of one of the edges, about 1/2 inch from the edge. Go to the opposite side, and place another staple. Repeat with the remaining two sides. Staple every 2 inches all the way around the paper.
Let dry flat. Do not rush the process with a hair dryer.
Once paper is dry, tape masking tape over staples and onto the board. This creates a dam, keeping the glazes on the paper and preventing the paint from going over the edge and then seeping underneath.
When the painting is finished and completely dry, remove staples with a flat staple remover, "cats paw" tack puller, narrow screwdriver, or a dull kitchen knife. Place the staple remover under the paper, not on top.
There are two options for framing. One is to cover the staple holes with a mat. The second is to "float" the painting. With a straight-edge tear the edges of paper just inside the staple holes, creating a new deckled edge.
Heavy-duty Staples and Popsicle Sticks
Lay the soaked watercolor paper on a board made from 3/8" plywood.
Use a staple gun to drive 1/2" heavy duty staples through wooden popsicle sticks placed along the edges of the sheet. Two sticks in each corner and one stick in the middle of each long side are enough for a 22x30 sheet. The sticks distribute pressure over a larger area of the sheet than staples alone. They grip the paper with thee texture of their grain, which eliminates tearing. When it's time to pry the staples out with a screwdriver, the sticks take all the abuse caused by forcing the screwdriver under the staple.
Attach with Brown Gummed Tape (packing tape, butcher's tape)
(The type you have to wet to get it to stick. Not the type with the re-inforced threads running threw it, but the plain paper tape. It can be found at most good office supply stores or mailing supply stores.)
Note: New specialty tapes are also available that are self-adhesive, clear, waterproof, and capable of holding dampened paper. They are sold by the roll at art supply stores.
Cut four strips of 2" wide brown paper tape, about 2" longer than the length of each of the edges.
Soak the watercolor paper as in previous examples. Drain the paper of excess water and lay it on a smooth, nonabsorbent board (gator board, or plywood sealed with varnish). An alternative to varnishing the plywood is to insert a piece of plastic wrap or tinfoil between the paper and the wood to prevent any leaching of acids from wood to paper. Make sure the paper is lying smoothly by gently pressing out any air bubbles from center to edges with a clean damp sponge, a large foam brush or with the edge of your hand. Dab along the edges with a paper towel to absorb excess moisture. (If either the paper or the gummed tape is too wet, it will not stick well.)
Pull the paper tape through water in a shallow container. Let the excess water drip off. Apply immediately to the watercolor paper. Smooth out with your hands or a sponge. (Alternative Method. Lay a strip of brown paper tape on a hard surface, glue up. With a damp sponge gently moisten the glue backing, being careful not to over wet. Lay the tape along one edge of the paper, covering about 1/2" of the paper, the rest of the tape on the board. Smooth out the tape quickly from the center to each end.)
Repeat with the remaining three pieces of tape.
When all four pieces are in place, use a clean dry cloth or paper towel and press the tape firmly against the surface of the board and paper to get maximum holding power. A few staples may be added, if desired.
Dry the paper flat overnight. Do not rush the process with a hair dryer. If possible, keep an eye on it as it dries and press down any sections of tape that appear to be lifting. You may need to moisten the tape again in that location.
If the stretching fails because the tape pulls away on two sides, soak the sheet again. Gently remove the remnant of the tape after the glue has dissolved, and stretch the sheet once more.
If you are concerned about painting right up to the brown tape border around your paper, you could either take a straight edge and draw a line about 1/8-1/4 inch in from all the edges as a guide or you could take masking tape and overlap your paper edge by 1/8-1/4 inch. This will give you a nice crisp white border around the painting.
When you have finished your painting and it is fully dry, cut through the brown tape at the point where the watercolor paper ends. Use a razor blade, X-acto knife, or utility knife with a steel straight edge to guide the blade.
Brown paper tape will still be stuck to all the edges of your paper. If you did everything right, you will not be able to remove it. Don't try peeling it off as you might tear your painting. Instead, cut along the inner edge of the brown paper tape and remove your painting.
Peel as much of the remaining tape off your board otherwise it can build up on the board.
Finally, soak the tape on the support board with a sponge, and scrape it off with a putty knife.
Note: Don't use masking tape to fasten wet paper to a support board; it will not adhere to the wet paper.
Tip: Use different color sponges for smoothing the paper and for moistening the gummed tape. You don't want to accidentally wipe gum onto your sheet of watercolor paper.
Oil Painter's Wooden Canvas Stretcher
Some artists stretch watercolor paper by folding and stapling or tacking it around the edge of an oil painter's canvas stretching frame.
Wheat Paste (or methylcellulose) method
Use a mucilage (gum-based), wheat-based, or other starch-based water-soluable glue. (This was the technique of choice before the advent of the brown gummed packing tape method.)
Position dry paper on mounting board. Mark the edges with a pencil.
Prepare the wheat-paste or glue.
Soak your paper, taking care to blot the excess water from the paper.
Lay the soaked paper on a different, clean board.
Using a clean utility brush apply liquid adhesive in a 3/4" strip around the inside edge of the pencil outline on your mounting board.
Lay your blotted paper within your marked margins and smooth flat with a damp sponge.
Lay board FLAT while paper dries.
Cut painting off board. Remove old paper and glue residue as best you can, before stretching a new sheet.
After the paper had soaked for about 10 minutes, run a bead of Elmer's Glue around the edge of a 1/4" Masonite board. As you take the paper out of the water, roll it up. Lay one edge on the Elmer's Glue and unroll the paper onto the Masonite. Smooth out the edges. Cover with newspaper, add weights and let sit overnight. When the glue has dried, tear off the newspaper. (If some of the newspaper sticks to the watercolor paper, drop some water on the area, let sit, then rub off. When the painting is complete and dry, cut the watercolor paper off the board, inside the bead of glue.
For a demonstration of this method see the DVD "Portraits in Watercolor" by James Kirk.
Tileboard Endcaps over Masonite
Cut a piece of 1/8" tempered Masonite one inch smaller than the paper on all sides.
Fold the 140lb wet paper over the edges of the board, and then secure with strips of mitered PVC strips which are friction fitted over the folded edges of the wet paper. (These PVC strips are available from Home Depot or Lowes in 8' lengths. They are called tileboard endcaps.)
I have not been successful with this method.
Ken Bromley Paper Stretcher
This is a patented stretching board that comes in three sizes: 20"x28" (Full Imperial), 13.5"x20.5" (1/2 Imperial), 9.5"x13.5 (1/4 Imperial).
The board is made from top quality lacquered wood that is grooved on all four edges. The back of the board has a fitting that will attach to a camera tripod.
1. After soaking the paper, place the paper on a towel on a table.
2. Place a second towel over the paper and blot off excess water.
3. Place the stretching board on top of the paper. The paper should be 3/4" larger than the board on all sides.
4. Fold the paper over one of the longer edges and pound in one of the 4 rubber gripper rods with a mallet.
5. Fold the paper of the other long edge. This time pull gently on the paper as you pound in the gripper rod.
6. Repeat the process with the shorter edges.
7. Dry the paper immediately with a hairdryer. Within 5 minutes from beginning to end you are ready to start painting.
8. Remove the gripper rods by inserting a screwdriver under the rod at the corner where there is a cutout.
9. Cut off the folded paper with a straight edge and a utility knife.
For more information go to http://www.artsupplies.co.uk. Email: firstname.lastname@example.org.
Ideas for constructing your own. Rout out a 5mm groove all the way around the edge of a varnished board. Use plastic coated clothesline for the gripper rods. Other options for the gripper rods might be insulated electrical wire or screen spline that is used to assemble window screen. Screen spline can be installed with a spline installer tool.
Joe Leahy's Watercolor Board
An anodized aluminum frame with stainless steel captive screws.
The frame comes in three sizes: 22"x30" (full sheet), 15"x22" (half sheet), and 11"x15" (quarter sheet). The Watercolorboard will be produced and distributed through mail order in 2007 by Judson's plein Air Outfitters (http://www.pochade.com). Information about the prototype can be found at http://www.watercolorboard.com/
Center the paper on the board. Place the sides back on and push the screws into the holes. Turn each screw clockwise until it makes contact and starts to pull on the paper. Its important to go around and tighten evenly so the paper is drawn in and stretched evenly. After all the screws have been started go around and turn each screw one or two full turns at a time until the screws feel snug and the corners are even.
As the "Quick-Turn Screws" are tightened, tension is placed on the outside edges of the paper so that after the paper has dried, the paper will stay flat and buckle free during the wettest of washes.
For more information go to Otto Watercolor Paper Stretcher.
Stretch a Completed Painting
Some artists suggest stretching only those pictures that are to be framed. Stretching only those paintings that are successfully completed, eliminates hours of preparation time.
These stretching methods can assist in flattening watercolors that have become buckled over time or those that were initially painted without some form of stretching.
Submerge the painting in water, being careful not to agitate the water or touch the wet paint. (If you are uncomfortable putting your painting under water, mist the back side of the paper. Allow the mist to soak in, and then repeat four or five times.)
After the paper has absorbed the moisture and softened, lay the painting on sealed plywood or homasote board and staple all four sides, 1/2" in and 3" apart.
After stapling, new paint can be floated in wet-in-wet if needed.
Let dry flat overnight.
Note: this procedure works with all types of pigments — staining, opaque, and transparent. If the paint moves in the process, lift it off with a damp brush. Wipe the brush with a tissue and lift more.
When the painting is finished and completely dry, remove staples with a flat staple remover, "cats paw" tack puller or a dull kitchen knife. Place the staple remover under the paper, not on top.