Sunday, May 2, 2010

Testing, testing...

Well, okay. I've been testing materials, so I decided to post a shot of my test. This is on plywood, testing the ground layers and an emulsion layer along with hand ground oil paints and a new glazing medium. The ground layer is gesso, a pretty traditional ground for tempera painting, which moved into use for oil painting as well, since oil was a pretty new medium 500 years ago. Painting grounds in Italy at the time were usually made using a glue derived from parchment scraps soaked in water to which whiting, in the form of calcium sulphate, was added. I made mine from rabbit skin glue (parchment scraps are pieces of animal hides) and calcium sulphate. I applied 2 or 3 layers of that gesso. I sealed half that surface with an emulsion ground of gesso mixed with water and lead white pigment. The (VERY rough) painting above shows the supposed colors that were used to paint the Mona Lisa. Spectral analysis of the paint surface was used to identify minerals in the paint layer. I bought as many of the pigments identified as I could locate. Then I mixed my paints using powdered pigments and grinding them with a muller into walnut oil. I packaged the mixed paints into tubes. The last thing I wanted to research and test was a glazing medium, since it's pretty well accepted that Leonardo (and pretty much every renaissance artist) painted a monochromatic underpainting, then laid transparent glazes of color over that to finish their work. The glaze medium I tested is made from Sanderac varnish (Juniper resin) and walnut oil. A passage from Leonardo's notebooks mentions these materials, and it seemed a good place to start.

My plan is to paint the piece as it may have looked when it was newly finished. Then, I'll apply a colored varnish to seal and finish the painting. The second picture with this post is a Photoshopped version of the picture of the test painting with a darkening layer over it.

This gives me an idea of how accurate the underlying colors are. Not too bad so far!

And, I have to include my disclaimer. I know the drawing of the painting and the color blends are not correct in my test panel. I wasn't trying to be dead on in appearance at this stage, just testing materials.

(As a side note, the test painting is on a chunk of plywood that also had a large amount of Karo syrup stage blood all down one side of the panel. THAT'LL be interesting once the red starts showing through the paint!)

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