Friday, December 12

How to Use Gesso

Today’s Image

In the Studio

Today's Image is Gesso. It’s that ubiquitous stuff that artists appear to take for granted. Not having been raised around art or the creation of art, this gesso stuff was interesting to me as I renewed my interest in art and painting. I didn’t even know how to pronounce it—was it GEH-SO with a hard G or JEH-SO with a soft G? Seems like a simple question, but you’d be surprised the number of hits it took on Google to find out (12). The winner was This was after visiting and (they use it to prime their toy soldiers before painting). By the way, it’s JEH-SO with a soft G as in “Jesse.”

I spent a little while researching the mystery, via Google of course, and found out a lot about gesso, and probably more than anyone cares to know including me. Seems it’s been around for a long, long time in the art world, but it’s had a rebirth of sorts with the advent of acrylics. Here’s what Wikipedia tells us:

Classic (my term) gesso is the Italian for "board chalk” (akin to the Greek word "gypsum”), and is a powdered form of the mineral calcium carbonate used in art. Gesso was traditionally mixed with animal glue, usually rabbit skin glue (what is that?), to use as an absorbent primer coat for panel painting with tempera paints. It is a permanent and brilliant white substrate, as long as it is used on wood or masonite. This mixture is rather brittle and susceptible to cracking, thus making it unsuitable for priming canvas. In Geology, Italian "Gesso" corresponds to the English "Gypsum", as it is a calcium sulphate compound.

Modern acrylic "gesso" is actually a combination of calcium carbonate with an acrylic polymer medium latex, a pigment and other chemicals that ensure flexibility, and ensure long archival life. It is sold premixed for both sizing and priming a canvas for painting. While it does contain calcium carbonate (CaCO3) to increase the absorbency of the primer coat, Titanium oxide or titanium white is often added as the whitening agent. This allows the "gesso" to remain flexible enough to use on canvas. High concentrations of calcium carbonate, or substandard latex components will cause the resulting film to dry to a brittle surface susceptible to cracking. Typically, a canvas should be sized prior to being gesso'd as a sizing coat will sink into the substrate to support it as opposed to a gesso coat which is just put on top of the substrate.

Who knew? I even added Gesso to the Artists Factoids section of the Orbisplanis Art Blog-see the right-hand column.

Anyway, as I read about its many uses, I experimented with it. Its main use, of course, is as a primer for canvas. Most store bought canvases are already primed so they don’t really need it. I think some artists like to apply even if it’s not needed because they just enjoy the process.

There are two reasons I like gesso:
  1. I like the rough texture you get when you paint it on the canvas or whatever support you’re using. You can get as fine or as coarse a texture as you like just by how carefully or sloppily you apply it-the more sloppy, the coarser. A coarse texture provides a way to adjust how the paint sits on the surface, and you can get all kinds of different effects, which I like. It lets you emulate different artists’ styles. The acrylic I’m working on now has a very coarse texture, which complements both the motif, a seascape, and the style, which is a very loose, almost abstract, brushstroke that works well, I think, with the distant and misty view I’m trying to achieve.
  2. Number 2, and I guess you can say the main reason I like gesso is because you can use it to re-paint your canvas at any time: whether you’re in the midst of your masterpiece or even if you have already completed it, varnished it, and hung it on the wall—you can still apply gesso to it. Now partly it’s economical, you can use and re-use your canvases over and over and over again. But mainly it takes the pressure off of me not to make any mistakes. That is, it allows me to just relax and paint away, knowing that I can fix whatever I don’t like whenever, even if I’ve ‘finished’ the painting.

If only there were Gesso for your life.


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