We are starting to get a glimpse of the start of the outdoor painting season approaching in the mid-Atlantic region. Soon, deciduous trees will start showing their leaves. The early bulbs are coming up. In the east, atmospheric haze will start to make its presence known both in the color of things at a distance and the high humidity that makes outdoor life so uncomfortable.
Painting outdoors, referred to as “plein air”, provides a variety of challenges. On any given day, my indoor “studio” does not have ants, bees, flying little green bugs, and a host of spiders that somehow insist that paint is a substance they need to embrace. It may be intriguing sometime in the future when a number of plein air paintings are analyzed and pigment cross-sections extracted from the paintings contain the remains of biological materials that became entombed during the painting process.
One of the variables that should be under control and not pose a physical or logistical challenge is the selection of a painting support. Plein air painting, as those who do this frequently, is not the place for large stretched canvases. The uninitiated painter soon learns the fundamental purpose of canvas. It was used as the means of locomotion on sailing ships by harnessing the wind. The same hold true for the plein air painter. A taunt canvas will catch the wind and turn the pochade box or French easel into a flying vehicle. Since a moving easel is not altogether conducive to painting, some modification must be made. While water jugs, rock bags or tie-downs are needed to stabilize a painter’s easel outdoors, a solid painting support, along with strategic placement of the easel can lower the chance that the easel will become a projectile.
Solid supports offer a variety of advantages for both the plein air and indoor studio painter. Within the realm of oil paint, it is well documented that the paint itself is not a structural element in a painting when the work of art is first executed. Note, this changes later and I will explain why. When oil paint is freshly applied it is soft and pliable. As it ages it becomes progressively brittle due to cross-linking of the material as it incorporates oxygen molecules. A stretched canvas is flexible. Many painters rave about the “spring” in a stretched canvas and prefer to paint on this type of construction. Over time the canvas remains flexible but it too oxidizes and gradually starts to fail. Old paintings are relined to provide structural support for the steadily weakening canvas. If a canvas is allowed to deteriorate far enough, it is the ground and the paint that take over being the supporting entity. This is a recipe for disaster as the brittle paint and canvas cannot stay integrated.
Even fairly new paint can display a high degree of embrittlement. A colleague provided a photograph that illustrated the effect of using a canvas stiffener on the back of an oil painting. The brittle oil paint could not take the stress of having the canvas shrink after it was sprayed with the stiffener and the tension was relieved in a most undesirable fashion. A large part of the painting came off of the canvas. This is not meant to condemn canvas stiffeners. They can be used BEFORE any ground or paint is applied to tighten a slack canvas. Also note that the same kind of failure as demonstrated by the spray stiffener, might have occurred if the artist had re-keyed the completed painting with enough force to over-tension the canvas.
A simple solution to the potential damage caused by a flexing canvas is the use of solid painting supports. An artist sacrifices the “spring” of the canvas on a stretcher but gains a high amount of protection and longevity. The choice of supports varies dramatically in type and price. The basic method of construction is simple. A rigid support is glued to a painting surface. The combinations are broad and can be customized to suit the painter’s style, budget and environment.
The solid support can be made of a variety of materials. The choice may be as simple as 6 or 8 ply acid-free mat board with canvas adhered to it. Wood is another popular alternative. Supports may be constructed out of cabinet grade birch or maple plywood, marine plywood, medium density fiberboard, solid wood, hardboard and proprietary wood preparations. Particleboard or chipboard seems to have been avoided in the manufacture of painting supports for many good reasons. Each support has advantages and disadvantages. Weight and long-term stability are issues with wood derived products. Some of the stability issues are mitigated by the use of barrier coatings to stop the migration of acids inherent in wood products into the painting surface material. Solvent-based polyurethane appears to be the preferred method of stopping migration and warping due to changes in temperature and humidity.
Metal has appeared as a support for solid painting panels. Simple 2 mm thick aluminum or the more sophisticated “sandwich construction of aluminum with a polyethylene core followed by another layer of aluminum are stable but expensive ways of creating a solid support. The art materials trade refers to these panels as ACM or aluminum composite material.
The painting layer is of a more traditional nature than the solid support. Artists may choose cotton or linen canvas, acid free papers, resin impregnated papers or the panels themselves as a painting surface. In many cases the surface alone requires extensive preparation in order to make it suitable for painting. It also has the drawback of not having a secondary support. If the solid support fails, the painting fails as well. A secondary painting surface (canvas, paper, etc.,) provides a “lifeboat” that can be moved to a new support.
Much discussion has been focused on how to adhere the painting surface to the solid support. It is open to debate. Polyvinyl acetate glues offer moderately good adhesion but become brittle over time. This can lead to delamination. Since the glue becomes brittle, it can be scraped off and reattached to its support easily. Other more permanent adhesives include acrylic mediums and gels, ethylene vinyl acetate and reversible conservation thermal-set adhesives.
Surface preparations can range from traditional oil or alkyd grounds, acrylic dispersion grounds and acrylic primers with additives to make the painting surface more or less absorbent. While solvent-based oil grounds are comparatively plain, acrylic dispersion primers may be modified to contain hard resins, porous materials and texture.
With the variations described in this article, about 4 dozen practical combinations are possible. With so many choices, an artist needs to select materials that suit a style of painting, framing/presentation methods, ease of preparation and cost.
Good luck this summer painting outdoors. As it is every year, it seems like it will be a dry, hot one in the Middle Atlantic States. Wear loose clothing, a hat and try not to get sunscreen mixed into your paint.
The Syntax of Color
Original Grammar of Color Essay
Vol: 1 No. 16 (Published June 2005)