Installation Part 2: Painting the Canvas

After our experience painting in the Early Eocene case, where we ran into a variety of obstacles, we decided we’d do the next case (Late Eocene) differently. One of the biggest difficulties of painting directly in the case it that you have to paint vertically, on drywall that — despite priming — soaks up paint. Which means you need lots of paint on your brush for every stroke, which of course means lots of trips back to the paint can. Very time consuming. For this next case, we opted to continue painting, but this time on canvas. Now we’d have a nice horizontal surface to work on, it would be portable, easy to trace the exact design onto, and we could thin the paint so it would be easier to work with. Easy peasy, right? Well, sort of…

Step 1: Convert the design into line art

Photo of printed outline of the Late Eocene mural

Casey and Tib discuss our tracing options

The projection system we’d initially considered didn’t work out, so we decided to trace off of a printed model. Once traced, the image would basically be a gigantic paint-by-numbers. But how to trace a digital drawing onto canvas? It involves multiple steps. First, we went back to the drawing board and took all the colors out of the digital image. Why, you ask? So we could print in black and white. Where the colors used to be, we entered the corresponding numbers. Once this black and white version was done, we took it to a massive printer. Even then, we needed to print multiple sheets to cover the entire canvas — remember, we were working on a canvas approximately 11 feet by 5 1/2 feet.

Step 2: Trace the printed image onto the canvas

There are multiple ways to trace any given image. There’s tracing paper, of course, as long as you don’t mind your final image being on thin translucent paper. We needed our image on canvas, so that option was out. You could use a light table or light box, which makes the original image and your tracing substrate appear to be translucent by lighting them from below, but then you’re limited by the size of the table/box. With our 11 x 5.5 feet dimension, light-boards just weren’t a possibility. So we turned to graphite paper.

photo of graphite paper sheets on top of the paper mural outline.

Sheets of graphite paper on top of the line drawing. When tracing, the graphite paper gets sandwiched between the canvas and the top sheet, graphite-side down.

The way it works is that you have your final substrate (in this case, the canvas) on the bottom, graphite paper on top (with graphite-side facing down), and finally the image you’re tracing on top of the graphite paper. Using a ballpoint pen or another tool that can also press down hard, trace over the lines on the top image. The pressure you exert will cause the graphite to stick to the canvas, and when you pull it all away it looks like someone’s traced with pencils. Fun science fact: graphite and diamonds are both allotropes of carbon, but because of key structural differences, they have very different properties. Essentially, graphite is made of flat layers of carbon lattice sheets held together by weak intermolecular forces; within the layer, the carbon bonds are strong, but between layers the bonds are weaker. With a little friction, you can make the lattice sheets shift in relation to each other (which is why graphite is sometimes used as a lubricant); with more friction, the sheets will eventually shear off. So, when you rub graphite against a substance, such as a piece of canvas, the pi bonds holding the sheets together break, causing sheets of latticed carbon come off the graphite structure and deposit on the surface — which is exactly what we want when tracing. Ta Da! Thanks, Physics.

photo of graphite tracings on canvas

During tracing, the graphite’s transferred to the canvas so you can paint within the lines.

Step 3: Paint by numbers

paint swatches and mural color palette

We used over 300 colors in the original Late Eocene image. Our next job was to narrow down the choices, and match the colors to paint swatches. Whew!

Technically we started step three around the same time as step two, since we painted the background sky, grass, ground and pond before we got down to the nitty gritty tracing. Since we had lots of sky, grass, ground and pond to cover, we went ahead and bought loads of paint in those exact colors. The rest of the colors, well, those were a bit trickier. The original image for the Late Eocene case actually used over 300 colors. We couldn’t afford to buy pints of each 300 colors, nor would we need to since some colors were only used in small amounts, but we’d definitely need to mix at least 100 different colors, most of them different shades of green. I’m sure there’s a science to mixing colors, but for me, I just mix until the color in my pot matches the color of the original image.

photo of the late Eocene canvas during painting

The easy part is over, now for the highly detailed shrubbery. Stay hydrated!

Paint by numbers seems easy, and it’s not particularly mentally challenging. It is, however, an endurance test when your canvas is as big as ours. To work in the middle of the canvas, I’d often have to sprawl across it, or even climb onto the table and sit right on the canvas, and hold that position until the tree or shrub I was painting was done. I had a series of theater tech students helping me, and it still took two months and two location changes. This particular painting had much more detail than the previous painting: it depicted a more open environment where you could see more foliage, which of course meant we had to paint that foliage.

Step 4: Cut and paste

Once the painting was finished, we had to cut down the canvas so it would fit in the case. This required about  7 rulers, lots of pencil marks, and careful use of scissors. We’d primed the case with wallpaper paint primer, and had intended to use wallpaper paste when we discovered the miracle of repositionable spray adhesive. We had just tacked up the canvas in the case to make sure it had been cut properly, and we intended to make marks to help us line it up again later. Lo and behold, it actually looked pretty good with just the tacks, which were hidden from view by the light fixture! If we could put up the canvas with the upholstery tacks and just a little adhesive, it would be so much easier to remove when changing out the exhibit, and it wouldn’t destroy the canvas. We undid one side of the canvas, sprayed the wall with adhesive, and rolled and smoothed the canvas back into place, then did the same thing to the other side. At last, the canvas was in place, and we were almost ready to install the specimens. A quick layer of paint on the base-boards so they tied in with the background, and voila, it was done. The only thing left to do was get the specimens ready for the public, but that’s a story for the prep lab to tell.

image of late Eocene Wyoming, when the climate was warmer.

Before: the original digital design for the Late Eocene display (41.3 – 33.9 million years ago).

Late Eocene specimens in the display case

After: the canvas is up, and we’ve populated the scene with a couple specimens. There’s still more to do: adjust the light levels, add more specimens, and put up labels.



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