Stretching Watercolor Paper

The first question you might be asking is why would you stretch watercolor paper?  While it is not totally necessary, stretching makes the surface of the paper lie flat and accept the paint without buckling.  For larger works, this is a big help, especially for heavy washes and large color applications.  Methods and materials vary, but there is surely a method that appeals to you and the way you approach your creative work.

Probably the most widely used stretching method is the taped edge technique.  You will need a smooth, clean board of something like tempered Masonite or a new drawing/stretching board.  This provides the type of surface against which the paper can lie until it is dry.  You will also need wide gummed tape, scissors and a razor knife or utility blade. 

Begin by thoroughly wetting your paper.  All papers but the very heaviest benefit from soaking and stretching.  The best place to soak the sheet is in a clean bathtub.  (Doing several at a time is good use of the prep necessary for the stretching process.)  Allow the paper to lie submerged in cool water until you can gently curl up a corner with little resistance.  Under-soaking the paper means it might have “a mind of its own” and stubbornly buckle.  If you over-soak a sheet, you run the risk of dislodging the sizing and changing the overall performance of the sheet. 

Once thoroughly wet, lift the sheet by one corner and allow excess water to run off.  Blot the surfaces (both front and back) with a clean sponge, removing additional excess moisture.  Lay the sheet out on your mounting board and smooth with your hands. 

Use unspliced lengths of moistened, gummed tape along all edges, gently pulling and smoothing the paper as you attach the tape.  If you place tape along a long edge first, make the opposing long length your second side attached.  Then continue with each of the short sides.  Set it aside and allow the paper to dry completely. 

Once the paper is bone dry, cut it from the board.  The gummed tape that remains on all edges of the paper can be trimmed away at any time in the future.  If you should attempt to pull it away, you can cause damage to the sheet.

Another method of stretching employs the use of common canvas stretcher bars.  Join the four pieces of the stretcher and soak the paper as described above.  The paper should be one inch larger on all sides than the stretcher bars.  Use one of two attachment methods.   Traditionalists use gummed tape, but a faster method is to use staples.  Staple the page along the outer edges of the stretchers.  It might help to lay the paper face down and then set the stretchers on top.  Stretching then involves lifting the edge and attaching to the outer perimeter of the bars. 

You can also mount watercolor paper to acid-free backing board with wheat starch.  It requires a bit more prep, but is a great way to insure a rigid work surface and no warping.  Soak your sheet and then allow it to dry almost completely.  Apply a layer of wheat starch to the back of the paper and set it on the backing.  Apply even pressure and give it time to dry.  Perfectly flat, unbuckled and eager for paint!

How To - Stretching Watercolor Paper

For decades, watercolorists have used simple yet effective ways to hold their saturated watercolor paper flat as it dries. The purpose for this "stretching" is to insure a flat, pillow-free surface on which to work and to allow the painting to dry flat for ease of mounting and framing. Some of the simple, direct methods of stretching include the use of tacks and different types of tape. Newer materials now exist to simplify the process, but many artists stand by their tried and true methods.

But before you can stretch a sheet, there are tips that will help insure success. Perhaps the most crucial step in proper paper stretching is the degree of soak given the paper. Some professionals prefer to "spot dampen" their paper, allowing a very specific control of wet-on-wet work. This can be accomplished by using a mist sprayer to saturate certain areas within the full sheet area. Sprayers that have a very light spray broadcast--those that spray very small droplets--work best.

Such sprayers can be purchased at art material supply stores. Mist methods also work very well for watercolor blocks, which cannot be totally immersed.

When overall, thorough dampening is desired, a deep soaking is considered the best idea. This total submersion affords the fastest and most fully saturated soak. Some care should be exercised, however. If paper is allowed to soak too long it can become fragile and is easily damaged. If not soaked long enough, it will resist stretching, may not be evenly "opened" to pigment and might not flatten smoothly. An average of 30 to 45 minutes usually works best for mid-weight papers. Really heavy papers may require a longer soak, so some experimentation will help. Warm water slightly speeds the saturation process, but avoid hot water.

Where to soak the paper is always a consideration. Obvious choices include the bathtub; but, in studio situations, other options might be needed. Special trays are available up to around 30" x 20". Alternatively, builders' supply outlets offer trays for mixing mortar or potting mixes, and these large trays are perfect for soaking sheets of watercolor paper. Some artists use small children's wading pools for full sheets or oversized papers.

Remember to allow the soaked paper to rest for a short time after removal from the water. Lift and hold the paper by the two top corners, which will shed excess surface water. Then lay the paper in a draft-free area to let the moisture even out. After about 10 minutes, the paper is ready to stretch.

One benefit of thorough soaking is the ease of paper sizing at that softened, pliable stage. It is very easy to size dampened paper and to create a feathered edge simply by pulling the wet paper into sections. For exact sizing, decide on the dimensions desired. Lay the dampened paper over a sharp edge, like that of a counter or desk. Gently pull the paper down, using the sharp edge as a cutting device. The result will be a straight tear and a soft-deckle edge.

Once the paper is evenly saturated, the stretching can begin. A board of some sort is required to which the thoroughly dampened paper can be attached. The old world purist's method is to tack the edges of the paper to a wooden board using thumbtacks. But, over time, the perimeter of the board begins to deteriorate. A more modern method is to attach the wet paper with gummed mounting tape (brown packaging tape), which grips the edges of the wet paper and holds it fast to the board. (Allow a 1" overlap on all sides of the paper to insure a good grip.) With the tape attached to the wet paper edge, simply moisten the dry side and stick it to the mounting board. This taping method works well on Masonite and wood. New specialty tapes are also available that are self-adhesive, clear and waterproof, yet capable of holding dampened paper. They are sold by the roll at art supply centers.

Perhaps the most interesting of the stretching methods are the new clamp and strip systems. These make fast work of preparation. Some of these boards employ a rigid plastic wrap-around edge that surrounds the outer border of the paper as it attaches to the backing board. The wraparound edge is held firmly in place with a second tap-in strip, easily and quickly assembled with a lightweight mallet. The hold is strong, facilitating all weights of paper up to 300 pound.

Other systems use a tap-in strip and slot along the outer edges of the mounting board. The paper is caught between the groove and the stretcher strip, thereby locking the paper in place. One advantage of this style of stretcher is that it goes on very quickly and holds weights up to 140 pound. This system allows for the efficient use of lighter weight papers.

Any of these stretching methods can also assist in flattening watercolors that have become buckled over time or those that were initially painted without some form of stretching device. To stretch a completed watercolor, mist the back side of the paper. Allow this mist to soak in, and then repeat. It may require as many as four or five mists, but the paper will slowly absorb the moisture and soften. It is then ready for stretching/flattening.

How to Stretch Artist Watercolor Canvas

Stretching your own canvas is fairly easy once you know the procedure and have the proper tools and materials. Note that the canvas referred to below is pre-primed; but you could also use the following procedure with raw canvas and, after it has been stretched, prime it with two coats of acrylic gesso. Please read through all of the instructions first, since certain steps must be prepared for in advance.

First you will need to gather a few tools and materials: canvas pliers, stapler/staples or hammer and tacks, stretcher strips, and canvas. In addition, a T-square is convenient to help you insure that the stretchers are square. Then follow these steps to stretch your canvas:

1. Select the appropriate-sized stretchers for the canvas you want to build. Your art supply store has a variety of pre-cut wooden frame rails (or stretcher bars) that have interlocking mitered edges.

2. Once your stretcher frame is assembled on a flat surface, you should verify that it is square. Do this by taking a tape measure and checking that the diagonal distances from both opposing corners are equidistant. (They almost always will be.) If you encounter an offset, you can correct it by attaching a small metal right-angle brace on the inner frame corner. A small plywood right-angle triangle attached to the rear frame corner will also help correct any shift.

3. For frame rails longer than 36 inches, an interior brace should be inserted between these rails to support them from bowing inward after the canvas has been attached. This will also protect against frame distortion during periods of fluctuating humidity. If this type of support rail did not already come with your pre-cut frame, you should cut a piece of similar wood and attach it with the type of braces detailed in step 2.

4. Take the canvas and lay the primed side down on a clean, flat surface. Place the frame atop the canvas and then cut away any excess material so that there are two inches of excess canvas bordering the frame on all sides. It is important that you leave this border material because this is what you will use to grip, stretch, and attach the canvas to the frame.

5. Fold one side of the canvas over one of the shorter frame rails and then attach a canvas tack at the center of the outside edge of that rail.

6. At the opposite side, use canvas pliers (which are similar to regular pliers except they have a broader gripping area) to grip the canvas at mid-rail. It may be helpful for you to set the frame upright while doing this. With a firm grip, pull the canvas until a straight crease is formed to the tacked end. While keeping tension on the canvas, insert another tack at the center edge of the rail, just like the other side. Note that you may also use a staple gun/staples instead of tacks. (The Arrow JT-21 is easy to use.)

7. Move to the next frame rail (one of the longer ones) and repeat steps 5 and 6. As you do, you will notice a triangular canvas crease as you attach the third side and then a diamond-shaped crease when the fourth tack is attached on the remaining mid-rail.

8. Now, place temporary tacks at all four corners. Starting with the center of one of the long rails, grip the canvas tightly with the pliers and fasten tacks at 2" intervals. Repeat with several tacks in both directions (from center) and then switch to the opposite side and repeat this process. Continue working from the center until both long sides are completely tacked down to all but one inch from each corner, stretching the canvas evenly as you proceed.

9. Once both long sides are finished, remove the temporary tacks that you fastened in step 8. Now repeat the same fastening process for both of the short sides, working out from the centers. For smaller canvases, one entire short side can be fastened first, followed by the opposite side. Larger canvases should be rotated several times to evenly stretch the material over the frame. Note that a primed linen canvas (oil-primed linen, in particular) will normally require that the tacks be placed closer together, due to the limited stretch of this material.

10. Fold and pleat the corners of the canvas and then neatly wrap them around to the rear of the canvas frame. Keeping tension on the material, tack all of the excess cloth to the rear of the frame so that it is neatly secured. Then place tacks on all four outer corners. This excess material is important to have in case you ever need to restretch or remount the canvas.

Any remaining canvas indentations or ripples can be reduced by moistening the affected area with a damp sponge. Be careful not to saturate, and allow the canvas to dry completely in a well-ventilated area.

Keep in mind that it is easier to stretch primed cotton and Polyflax canvas than it is to mount a primed linen canvas, since linen fibers do not stretch as much. Oil-primed canvas requires the most attention when mounting on a frame because it has virtually no stretch. When working with this type of canvas, you may have to remove tacks in wrinkled sections and then restretch and retack.

By following the above steps and using proper materials and a few tools, you can easily build your own canvas. With a little practice, the process becomes much faster and easier, almost to the point of becoming routine.