Posts Tagged ‘canvas’

New Materials: Absorbent Ground

Sunday, April 15th, 2012

If you have been following my blogs this year, you know that I have been looking for a satisfactory way to apply watercolor to canvas. Among other things, I found that gessoed canvas does not satisfactorily hold watercolor well enough to permit layering—called glazing—an important technique when using transparent watercolors. But then I came across an alternative surfacing material, similar to gesso, that claims to hold the color better—Golden’s Absorbent Ground, in matte white.

Directions indicate that multiple coats increase absorbency, so I decided to prepare a canvas panel sectioned roughly into thirds, which I would give one, two, and three coats, respectively, of the absorbent ground to test for my own edification.

I began by coating a 16”x20” pre-gessoed canvas panel with a single coat of the ground. I dipped my brush into water before applying the ground to make it easier to spread, but otherwise did not thin it. After it had dried for several hours, I taped off the left third and coated the remainder with a second coat, which I permitted to dry overnight before applying a third coat to farthest right third. The three sections were separated with pencil lines for easier identification.

absorbent-ground-test

After the third coat was dry, I applied separate washes of two watercolor paints, Winsor blue, red shade (phthalocyanine blue RS, aka PB15) and burnt sienna (a synthetic iron oxide red, PR101) across all three portions of the panel. Both paints have a staining quality, which is preferable for glazing purposes. Near the top of each, I lifted out swaths through both color blocks while they were still wet, both with a dry paper towel and with a damp brush. Once the base color had dried, I applied separate glazes of both colors over each of the color blocks. Finally, I again lifted a swath from the bottom of each dried color block with a damp brush. (The illustration above shows the finished test panel.)

The following day, the effect of the absorbent ground became considerably more apparent when I ran water over the entire panel and scrubbed it with a gentle brush. Most of the color washed off, but the absorbent ground had been stained to some extent by both base coats. The more layers of ground I had used, the more stain remained, as shown below.

absorbent-ground-washed

Conclusions: Does the absorbent ground improve paint retention? Yes!
Does the number of coats make a difference? With each successive layer of ground, the paint lifted less readily, although within a couple hours after painting, with a bit more effort and a damp brush, paint could be lifted out from even the triple application. After the paint had dried overnight, however, both paints had stained the ground and become more difficult to lift. It appears that the ground continues to absorb the stain until both the paint and the underlying ground have thoroughly dried (the ground having been remoistened by the application of wet paint). The more coats of ground there are, the longer they take to thoroughly dry, hence the more stain they absorb.

Recommendations: If glazing is to be used on (pre-gessoed) canvas, I would recommend, first, applying a minimum of three coats of the absorbent ground before beginning a painting and, second, leaving the base coat of paint to dry overnight or longer before applying subsequent glazes.

Additional notes: According to directions, “Due to the fragile, absorbent quality of the ground, finished paintings need to be protected.” Whether this protection must be in the form of glass or the equivalent or whether a spray varnish will suffice is not specified. Since my primary reason for using canvas instead of paper is to leave an exposed surface, my own inclination would be to opt for some kind of protective varnish or sealer rather than a glass or acrylic cover sheet. Such a solution might or might not be adequate—only experience will tell.

New Materials: Workable Fixatif

Wednesday, February 15th, 2012

As I have written about in my last few entries, painting with watercolor on canvas has been a crash course at the School of Oops. I’ll continue here with notes about my work on the pad canvas.

Despite my decision to use the pad canvas only after affixing individual sheets to stretcher bars, I decided to try it stretched only with clips. Firmly clamped to a backing board, my second sheet of canvas held its shape well and appeared to lose little area due to shrinkage.

Anticipation

In placing the subject, I mentally included the margin space on all sides to allow for later stretching and shrinkage. (Refer to the Faces and Figures gallery to see the finished proportions of “Anticipation.”)

When I applied glazes on this type of canvas surface, I found that lifting was still almost as much of a problem as it had been on the stretched and gessoed canvas (Joe Miller’s brand) I had used previously (see blog for January 1, 2012). So, when I decided I needed a final glaze to warm the foreground, I set the painting aside for several days to dry thoroughly (front and back) before spraying it with fixatif. Only when that was dry did I lay in my last applications of paint.

I had not used this type of fixatif before (Krylon Workable Fixatif), but it was called “workable” and stated that it “allows easy rework.” However, apparently that holds true only for the stated “pencil, pastel, and chalk,” not for watercolor. The watercolor beaded up on the fixed surface, and though I was able to do a bit of retouching, it was not satisfactory.

Out of desperation, I recoated the painting with the varnish (Krylon Gallery Series UV Archival varnish) I had used on my first canvas, hoping that that would provide a more friendly working surface that would accept top coats of watercolor. The paint continued to bead up, failing to adhere smoothly to the surface.

One of the few advantages of the seal appears to be that I can wipe off failed attempts without fear of leaving stains and smears behind.

Another advantage (admittedly a major consideration) is the UV protection it offers for any paintings that will not be shielded by UV-protective glass.

I would be interested to hear from others who may have found alternative fixatifs or sealers over which additional layers of watercolor can satisfactorily be applied.

Canvassing the Possibilities, part 2

Wednesday, February 1st, 2012

In my quest to familiarize myself with alternative watercolor surfaces for my work, I bought a pad of cotton watercolor canvas (Fredrix brand) to try. As I unwrapped the heavy pad, the weight of the sheets pulled the entire pad away from their backing board. The adhesive strip along the top was not strong enough to support the weight of the mass of canvas.

However, I decided to try using it as I would a pad of watercolor paper, as I supposed was intended. Using bulldog clips, I fastened the canvas pad back against the backing board, set it up on my easel, and got to work. After wetting, the canvas didn’t stretch but actually shrank. Where the canvas was clipped to the board, shrinkage was negligible, but areas that I had failed to clip shrank enough to form noticeable ripples in the fabric as it pulled diagonally against the clips. Having worked primarily with paper and stretched canvas in the past, I had not expected this to occur to such an extent.

In this case, to encourage more even shrinkage, before applying fixative, I reversed the canvas and, leaving it entirely unstretched, I sprayed the back with water, spreading the moisture with my hands to ensure even coverage. Then I allowed it to dry thoroughly. Most of the ripples disappeared as the canvas dried. Overall, the 20”x16” canvas lost approximately ½” in length (in width as seen in the horizontal orientation below) and ¼” in width (or in height as shown in the illustration).

Grasslands

Lessons learned: 1) Use the sheets singly, rather than on the provided pad, and 2) Stretch even page-like sheets of canvas before painting—it’s shrinkable cotton fabric, not paper. Whether on stretcher bars or by affixing the canvas to a sturdy backing, the canvas must be stretched before wetting. I will use 12”x16” stretcher bars for the remaining sheets, to allow enough edge to wrap around the bars.

More about my experience with the canvas next time.