Panel Prep Is Nearly Complete!

I thought I'd post a few pictures as the panels near completion of the gesso/surfacing/priming phase, and are nearly ready to transfer the cartoon onto to begin the painting(s)! Below is a shot of the gesso sottile on the panel. This is the fifth layer of gesso sottile, applied with a brush and leveled with a scraper.

As you can see, the surface has lots of irregularities that need leveling. After the panel dried, I sanded it smooth and scraped the final surface to eliminate any marks left by the sandpaper. That smooth, flat surface was sealed with a dilute mixture of clear shellac and denatured alcohol and allowed to dry, then a thin layer of lead white priming was applied. I also applied a second coating of lead white to the test panel. In the picture below, you can see the panels side by side. The panel on the left is the test panel. (Note the uneven surface...this is a result of having NOT put a sealer down before the walnut oil in the lead white came in contact with the surface. The hero panel on the right has a much more uniform finish.


Now, the panels will dry at least a week. once the panels are both dry, I'll likely do one last layer of priming, then I'll transfer the cartoon onto the panels and begin painting. The cartoon wil be rubbed on the back with powdered charcoal and traced onto the panels, then redrawn with umber oil paint. The picture below shows the cartoon taped in place over the test panel. You can see the (drawn) edges of the real painting, and how they align with the frame and panel beneath. I'm not convinced that the top edge is correct in my tracing, and have adjusted it on the final cut of the panel and the cut of the frame.



The image of the painting I liked for my cartoon was an infrared shot. It seemed to show more details of the piece that are usually hidden in shadow, such as the form of the entire chair Lisa is sitting in, and the structural elements of the parapet behind her. There's also a lot of detail in her figure and dress that isn't easily deciphered in other photos of the painting.

After the priming dries, I'll get pictures up of the work as it progresses ASAP!

Second time's a charm. (I hope!)

The hero panel has been re-gessoed! Hopefully it'll dry well, and will be sanded smooth next weekend. I tried a little something different with the process this time, ordering Italian rabbit skin glue to mix the gesso. It's an interesting product; darker thatn the stuff I'd been using, but lightens considerably when hydrated and melted. I applied the gesso with a wide brush and smoothed it with a thin, flexible scraper so that hopefully sanding will be minimized.
Once it's dry and smooth, I'll need to seal and prime the surface. In cross sections of Leonardo's work, it appears as though there's not a sealer between the gesso and the white lead layer. On my test panel, I tried applying a thin coat of white lead directly to the smoothed gesso surface. The walnut oil in the paint seems to have penetrated the gesso layer and stained it darker. I'm also thinking that it may compromise some of the gesso's strength. So, even though there doesn't seem to be any evidence of it in the magnified cross sections I've seen, I'm planning on making a dilute solution of white shellac (which is really CLEAR shellac) and denatured alcohol.I'll brush that over the gesso surface to seal it and protect it from the oil layers that'll be applied over it.
The lead white on the test panel is drying slowly, of course. It's a thin layer that I applied with a wide brush, then used a fan blender to smooth so that it's practically free of brush strokes. SInce Leonardo's technique was to use many thin colored glazes of paint to achieve the illusion of depth on his paintings, the underlying surfaces have to be as perfectly smooth as possible. Every step requires more research and intense focus.
The oil penetration on the test panel means I'm researching possible reformulations of the white lead priming to make a highly pigmented, thin and somewhat porous paint for priming the hero panel once it's smooth. I'll be having to grind more lead white paint soon, so I'll likely try some experiments with additives to the paint to give it the desired opacity, thinness and absorbency. One possible configuration will be to mix lead white pigment with the powdered gesso mixture I've been collecting as I sand the panels. I'm not sure what properties this will lend the primer, but that's the nature of experimentation, no?

Success!! ...sort of.

Well, after a week or so of diligently scraping down and smoothing the gessoed wood panels, in accordance to the traditional method, I was dismayed at making such slow progress.
The test panel developed a small crack in what I had planned as the top of the painting, almost like the crack that the real painting has that goes from the edge of the painting to the top of Lisa's head. I thought that I might as well try a non-traditional method of smoothing the gesso layer on that panel, and stocked up on various grades of sandpaper.
This morning, I got out my trusty palm sander, plugged it in and sanded away. I used 100 grit to smooth the gesso, and 220 and 600 to finish. It's BEAUTIFUL. Not without flaws, but one can see why the old masters used this surface for painting. It's snow white and smooth as glass. I had thought about doing a few passes over the panel with 1000 grit paper, but it's not supposed to be too shiny. The layer has small pinholes in it from the gesso being stirred too vigorously and standing on the heat too long, but I'm hoping they won't be noticeable in the final painting. And this is the test panel, after all. When I redo the gesso on the hero panel, I'll be more aware of those issues. I also decided that I'll invert the panel and put the crack at the bottom in the darker areas of the painting.
The hero panel has such severe cracking at the joint between the panel and the frame that it'll have to be stripped and redone. It's got damp rags on the surface now, and I should be able to scape off the gesso this evening. I've ordered new supplies and will re gesso that panel once things arrive.

The Gesso-ing!

Here's the first picture of the hero wood panel after a gesso grosso (a thicker undercoat of gesso) layer and five coats of gesso sotille (which is a thinner, surfacing gesso). I'm hoping that it'll dry nicely. There's a bit of grit in the gesso sotille that I'm not crazy about. If it sands out well, then I'll be satisfied. If not, I'll be removing the gesso and starting again! The panel as shown has been cut and shaped to the right size and put into a pine frame constructed like the flexible oak frame the actual painting is supported by. And of course the test panel is seen in the background. from this point if all goes well, the panel will be smoothed to a totally perfect surface and primed with lead white, and the drawing of the subject transferred to the panel. Then it's ink and underpaint time!