I wanted to see if I could use an acrylic medium to approximate the same quality of surface I get using animal protein (hide glue or casein) for my binder when making gesso. This will not be the same result as the commercial brands of acrylic gesso you see on the market. That’s more like paint. The goal of this is to keep it very thin, and sand it to give me a surface that’s smooth as marble.
My choice for acrylic polymer medium for this experiment was Golden’s GAC 800 medium. The description of it being “useful as a modifier when adhesion to chalky surfaces is desired” sounded good for this application. The solids I’m using are the same as what I use for traditional gesso: calcium carbonate. I sometimes also add titanium white pigment, but not this time. I wanted something more grey. The surface I’m applying it to is a medium thickness black mat board. The black will help me evaluate the coverage better, and again I’m trying for a grey undertone for the artwork I’m planning. I normally use a wood panel for my gesso, but I wanted to see if the acrylic would allow me to work on something a bit more flexible.
The mat sheet is in the center (approximately 18 x 24″) with 12 coats of my acrylic gesso mixture applied. I coated the back of the sheet with a couple coats of thinned medium (no solids) to keep it from warping. The amount of medium is roughly 10% by volume, but I haven’t been doing any careful measuring – just going by sight. In the end, I wanted something very thin, like a watercolor wash, or onion soup, so it has quite a lot of water. There’s a piece of the original black mat board on the far left. I placed a sheet of white copy paper on the right to show the contrast.
This bowl shows a small amount of the gesso left over, and helps show how thin it is. I applied a single coat on that black sample to the right. It dries relatively quickly – about 15 minutes to the touch, and the texture feels the same as the traditional gesso I make.
So far so good. I’m going to let it continue to air dry for a couple days, and then see how well I can sand it smooth.