This is an exciting new, albiet very old, way to use watercolor; a clear glaze of melted wax is floated over the surface of a finished watercolor painting creating a permanent, waterproof surface. It is amazing to put the wax over the watercolor image and see no change to the surface except an enrichment and deepening of the color. I can now create watercolor paintings on canvas and when the wax is applied the surface becomes as permanent as an oil painting. I do not have to frame the picture behind glass. The key to the process is the invention of a vegan gesso explained below.
Watercolor will float on top of an oil or acrylic gesso. Oil and acrylic gessos will not work. A vegan gesso has to be applied before you can paint watercolor onto wood or canvas.
These ingredients can be obtained from a sculpture supply store. I have listed a supply store on the resource page or perhaps you can find one in your area.
Making the gesso is quite simple.
- 2 cups prepared wheat paste mixture. Most wheat paste jars come with instructions for mixing the whole jar. I do calculations to make smaller batches. For 2 cups I mix 1/4 cup wheat paste into 1.75 cup water.
[For a very small run I will mix 1 Tablespoon of wheat paste in 1/3 c. hot water. Adding the following ingredients is tricky with this small of an amount because if there is too much chalk and clay, the gesso will not harden and stick.]
Add to the wheat paste the following ingredients in this ratio:
- 4 tablespoons of chalk
- 2 tablesoons of kaolin clay
- 1 tablespoon of terra alba (raw gypsum – NOT plaster of paris!!)
Continue adding the ingredients in the 4part to 2part to 1part ratio until a soft whipped cream consistency is achieved (see photo left). If you make the consistency too thick, there will not be enough wheat paste to adhere to the canvas and the whole business will wash off. Trial and error is probably the best method, and, in this case, less ingredients are better than too many.
I have found that the canvases need to cure for a time before using them to paint. If it has not had time to thoroughly dry out and bond the gesso may break down when water is applied. Let the canvas stand for at least a week before using it for a watercolor painting.
Once the gesso is dry you can paint with watercolor. The gesso creates a rich velvety surface and it is a joy to paint on it. It is also very forgiving. If you want to ‘erase’ and repaint, just wet the surface, use a soft paper towel and blot up the paint. I have done complete removals and then repainted the corrected image with no damage to the surface. The surface also accepts graphite effortlessly. I have not yet tried the gesso on stiff paper for pastel work, but I suspect it would work very well. Considering the ease of graphite, charcoal would probably be quite thrilling to use on the surface. However, you will not be able to put a wax overlay onto graphite, pastel or charcoal because those substances are free floating pigments. Wax works as a binder for pigments and when it encounters a free floater like graphite, pastel chalk or charcoal, it will bond with the pigment and create paint. Control of the resultant ‘paint’ would be tricky but it could be an interesting adventure.
Watercolor, on the other hand, is composed of pigments suspended in Gum Arabic which, when dry, is a solid surface. Wax will not interact with the pigments in a dry watercolor painting.
Test reproduction of a Fayum mummy portrait
Scientists studying the Fayum Mummy Portraits have speculated that some of the paintings were tempera under painting with encaustic overlays. To test the idea, I did a reproduction of an ancient mummy portrait.
Varnish with hot wax
Keep in mind that once the wax overlay is applied, no changes can be made to the painting other than heating and adding more wax.
If the surface is cold the hot wax will solidify on contact. Heat the board or canvas in a 170º Fahrenheit oven, or use a hairdryer or heat gun to warm the surface. However, heat guns and hair dryers blow the wax and create a fine spray of wax all over the work area. Because of that I prefer preheating in an oven.
Ancient references to encaustic mention super heated boards placed on embers from a fire. Since doing the experiment I have gotten an electric griddle (a modern equivalent of the ancient fires) and can leave the canvas or board on the griddle while working. The painting remains hot and the wax flows beautifully over the surface.