Summary: Artists need to understand the positive and negative aspects of painting supports. A support that appears stable and sound when first made will change over time. Part 1 of this essay focuses on canvas painting supports primed with acrylic dispersion primer.
Canvas stretched on fixed or expandable strips of wood is just like a drum. The tension needed to keep the canvas from buckling and wrinkling is a primary factor in the construction and engineering of stretched canvases. The springy feel of the taut fabric is a quality beloved by many artists. However, the tension that makes it so appealing is also the mechanism of its undoing. How could something that appears so delightful be so bad? I could say the same about potato chips, ice cream, chocolate chip cookies, and whipped cream. Appearances can be deceiving.
Here is what is happening. The tension applied to make a canvas stiff, and crisp creates a structure that is prone to movement, despite it being under pressure. A stretched canvas has lots of play in it for several reasons. Push a stretched canvas from the front or the back and it will deform and spring back to its original shape if a broad even force is applied. Poke at it in a concentrated area and a permanent dent or bulge can be formed.
In order to have a sound surface for applying any paint that dries by oxidation (oil colors) canvas must have multiple coatings of primer to protect the canvas from the oil binder in the paint so that it does not oxidize. These necessary layers of sizing and priming create a system that responds according to the rules governing the physical properties of materials. Let’s see how this works when an acrylic dispersion primer is used.
A well-primed canvas starts with a coating of sizing to protect the canvas and to help the primer form a protective layer for the canvas. The sizing aids in having the primer sit on the surface of the canvas rather than sinking into the fibers of the cloth so that the primer becomes a layer that has a discernable thickness to thwart the penetration of oil from the paint.
Acrylic primer serves a dual purpose to both protect the canvas and to be a suitable receptor for oil paint applied on top of the primer. Without the sizing and priming, the stretched canvas would suffer from long-term oxidation of the organic fibers, and dirt and grime would settle into the weave of the cloth.
Since the canvas is under tension, the threads will weaken over time. Applying sizing, priming, and paint modifies and integrates the entire structure. It now becomes a semi-rigid support. The canvas provides an active member for holding up the ground and paint layer. But over time, this relationship evolves. Oil paint becomes brittle as it ages. It eventually takes over a lot of the function of supporting the structure and the canvas takes on the role of keeping the painting attached to the stretcher/strainer.
Unfortunately, the canvas gets to have a critical “vote” in determining the fate of a painting. Some of that springy quality remains in a stretched canvas. But now when pushed or poked, it reacts in the way physics dictates. The brittle elements of the paint are strong but have little to no qualities promoting elasticity. That attribute was only present in the oil paint when it was young and supple. Now aged and fragile, the paint relieves the stress of being pushed by cracking.
The brittle nature of an oil painting on canvas plays itself out in other ways that manifest themselves in cracks and loss of paint. The traditional size used by artists for centuries was rabbit skin glue. It loves to take on water if the humidity becomes high and purge itself of water if dryness surrounds a work of art. The cycle of expanding and contracting rabbit skin glue causes microscopic breaks that eventually turn into the network of cracks we observe in old paintings. Our best efforts when stretched canvas is the system of support leads to inevitable deterioration.
OK, so now that we have had the cold slap of reality heaped upon us, let’s examine how we can mitigate this problem to avoid or retard this phenomenon.
Marion Mecklenberg’s of the Smithsonian Museum conducted extensive research on the behavior of stretched painting systems as well as on the paint and grounds individually. His work has shown that if you insist on painting on stretched canvas, the easiest thing you can do to dampen vibration, stop the potential of punctures originating from the back of the painting and avoid frightful corner damage when a painting is accidentally dropped on its corner is to mount a rigid support to the back of the stretcher.
It addresses the ills described above and is a very low-tech/high-value solution. If you are a klutz and prone to dropping sharp objects like utility knives or screwdrivers on the back of paintings, this advice will save your pictures. If you drop tools that hit the front of your paintings, the stretcher-mounted panel will not help this problem unless it is placed right behind the canvas. This method of putting the panel right behind the canvas painting, commonly called the panel-backed stretcher, was used in the 19th century. The use of a panel-back stretcher should be determined when the painting support is being fabricated. A backing board attached to the rear side of the stretcher can be done at any time and is advisable for all paintings as a means of keeping dust and dirt off of the back of the painting.
The other solution to stabilizing your support is to use one that is solid. It has many advantages. The choices for solid painting supports can be a bit daunting. One must decide if it is better to paint directly on a solid support or adhere a canvas to it and paint on that. Gluing canvas to a solid support has some advantages because if the substrate fails over time, the canvas can be detached and remounted to another type of panel. It also gives a painter the feel of the canvas so that the common complaints about the slippery, oily feeling when painting on very smooth panels can be mitigated. The end of Part 1.
Syntax of Color