Updated: Apr 21, 2019
I think I've finally managed to create an impervious canvas support for my images.
This canvas may look rather humble and unremarkable, but to me it sparkles like a gem. I think the most magical things often have a very lowly physical appearance.
It is made using a size of rabbit skin glue, and a gesso made of glue, oil and chalk. These are the materials that were used before the discovery of plastics.
I've never been happy with using acrylic gesso. I work with and for nature, and I am concerned about how acrylic paint harms the environment. Its highly processed form means it takes many years to decompose. If it gets into the water system, for example through the waste water created after washing brushes and other tools, there is a possibility that it will be absorbed in micro plastic form into the bodies of trees and animals of all types, including humans. It is made using a non renewable aspect of the earth, and its processing causes many harmful by-products to enter the environment.
Acrylic paint is a very versatile and interesting medium which I have enjoyed exploring in the past, but I hope now to create mediums myself with organic and less processed ingredients that will have the same kind of versatility.
I am doubtful regarding the compatibility of acrylic gesso with oil paint. Plastic does not form a natural bond with oil, so it is more likely to delaminate than when using a traditional organic ground.
Acrylic gesso dries out the oil paint over time, so it loses the sheen that gives an oil painting its characteristic depth and resonance. I suspect also that this drying effect may increase the possibility of fissuring and delamination.
I was disturbed to discover a few years ago that the paint had leached right through my acrylic primed canvases. I had thought that two layers of gesso were enough, but clearly not. If the oil in the paint gets into the canvas, it will eventually cause the canvas to decompose. It was this that prompted me to explore alternatives, and to go back to the original methods of sizing and priming a canvas for painting.
Rabbit skin glue has been used as a way of sealing the canvas for centuries, and stands the test of time, but its hygroscopic properties caused it to fall out of favour when acrylics became available. Acrylic does not respond to changes in humidity, but rabbit skin glue expands and contracts in response to the moisture in the air. This is relatively easy to manage, but perhaps more so before the days of central heating. If the painting is placed away from radiators, fireplaces and south facing windows then all is likely to be well.
There are also the ethical issues regarding the killing of an animal. I have struggled with the ethical side myself. My reasoning is it is the lesser of two evils. If the rabbits have had a good life and are killed humanely, and the rest of their parts are put to good use, then my mind is at rest. I plan to research a source for glue where this can be confirmed, and I hope I am successful in finding one.
After a lot of internet research, the acquisition of several out of print books, and a great deal of trial and error, I think I have created a support that will perform well. I think the difficulty has come from my use of cotton duck instead of linen, which is the fabric to which it is traditionally applied. The cotton duck needs many more coats of glue than the two recommended for linen, I think because it is a much thicker and more permeable fabric.
It is actually very time consuming, and perhaps because of this not very practical. I plan to change over to linen when I've used up my supply of cotton. It's more expensive but it will save a lot of time. I'm going to coat half of it with a layer of paint, and leave half just as it is. I'll need to leave it around a month before I'll know for sure that it has worked.