Show Your Work

Burden of Proof
Transcript of Rationale

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At the beginning of the year, I started a research project intended to calculate pricing information for painting commissions. A few months later, a simple series of reference charts had evolved into a complicated spreadsheet that priced paintings based on a method that could be described as a dissection.

The original reference charts were built in a file called “Coverage Estimator.” These were a series of tables listing a variety of elements that I could pick and choose from depending on what each finished work was composed of after completion. The first table listed common canvas dimensions by width, height, and price. Others contained price list information about the materials I used on the canvas. However, there were no common units of measurement for the materials listed, and no method for determining how much I had used for each canvas I completed. It was a simple idea with good intentions, but it proved too simple to do the job properly.

Clearly, the project had to evolve into a full fledged spreadsheet based application that could determine value based on more complex data, so I brought a software developer into the studio to help develop the formulas that would make this spreadsheet hum. Formerly named “Coverage Estimator,” a working copy of the file was made. The new one was renamed “Spreadsheet of Doom 2,” and this is the story of how it evolved.

The goal was to build a tool that would allow me to type in the dimensions and price of a canvas, and then have the spreadsheet automatically draw on supplied information about materials that go into creating artwork on canvas. To establish the scope of the new project requirements, I sketched out a cross section of a stretched canvas and labeled the different layers in order of application.

A few coats of acrylic polymer used as a fabric stiffener and mould deterrent helps seal and protect a raw canvas against moisture damage. Next, two or three coats of gesso create a ground on the canvas surface allowing paint to properly adhere to the surface. The actual painting comes next, and this was identified as a thick mystery layer, rich with unknown possibility and a distinct lack of quantifiable detail. Ignoring that ambiguity for the time being, I added more layers on top of the paint; first, two isolation coats for archival and restoration purposes, and finally two protective coats of varnish.

The next task was figure out how much material each layer required. With the layer cross section diagram in mind, multiplying the length of a canvas by its width provides the coverage area in square inches. According to my preferred paint manufacturer’s extensive website, one might expect a coverage estimate of 200-300 square feet per 1 gallon of acrylic polymer and gesso because these two products are more likely to be used over absorbent surfaces like raw canvas. The company estimates that 1 gallon of paint or acrylic medium—products usually applied to prepared surfaces—will cover around 400 square feet.

There were no data sheets available on the varying thicknesses I could expect a single coat of paint or the range of acrylic mediums I use, so I emailed their technical support staff with my questions. An email conversation with a friendly and knowledgeable artist ensued, and he was able to provide me with a document that introduced me to a new unit of measurement called the “mil.” According to this data sheet, there are 1000 mil in an inch, and, for example, a grocery store plastic bag is 1/2 mil, a human hair is 1-3 mil, and standard copy paper is 4 mil. At the very bottom of the file I found the prize, “Brushed paint application is approximately 5 mils or 300-400 square feet per gallon and as you increase your impasto you decrease your overall coverage.” Perfect.

By now I had compiled a substantial amount of data around area coverage and volume. Much of this information used different units, so I required a unit conversion calculator. I downloaded one for my phone, but to be sure I could access one if my battery drained, I had one built into the spreadsheet. Using this converter, I bashed square feet and meters into square inches to deal with matters around area, and converted gallons, litres and millilitres into ounces to deal with volume. I factored my gesso, paint, and acrylic medium layer calculations using a thickness of 5 mils.

In the broader sense, my goal was to make the whole operation so easy to use that I could get accurate information from it on my busiest or most exhausting days. I secretly daydreamed about having an assistant open the file and run the numbers through for me on days when I would rather watch someone type than do it myself.

Believing I had all the necessary variables, the data tables from my first spreadsheet file were separated into their own tabs to position all reference materials in the background, and work began on the front facing spreadsheet.

Using my cross section canvas drawing as a model, the first table we built mimicked the material layers. Starting at the bottom, we allowed one row each for recording the number of acrylic polymer and gesso coats. We left a big empty question mark in the middle where the paint would go. We provided one row each for isolation coats and varnish as the top two rows representing the outermost protective layers of the painting. All I had to do was copy and paste the precise name of the product from the Materials List into the Materials column, and the tables would reference the data associated with it to give me my cost per square inch of each material item.

The next table is more canvas specific; “Proposed Surfaces” addresses the labelling of each piece along with two columns for entering the width and height of each in inches. The square inches of each canvas are automatically calculated. Directly to the right, we begin breaking down the costs. The canvas prices are added based on prices paid for each, and the material costs appear in the column next to it.

Creating the Oz / In2 Calculator allowed my developer to crunch all those millilitres and gallons into ounces per square inch. The resulting numbers were tiny amounts of product costing pennies, but over an area of a few hundred or thousand square inches in a medium to large painting, the ounces and costs added up. For the canvas measurements I was calculating, all those numbers were gloriously presented to me on my spreadsheet with the sums in bold print along the bottom for easy referencing.

However, there was still the nagging issue of that gaping void on the drawing and in the spreadsheet. Having avoided that mystery layer until now, I had a good foundation in place to valuate my artwork and decent protection against anyone who might ask where my numbers came from, but there was still no art.

I thought back to my discussion at the law firm I was to paint for. The partner described his love of richly textured canvases; artwork with serious presence. He mentioned geometry, abstraction, his love of Jackson Pollock’s work.

Thickness seemed as good a place to start as any. I developed two groups of materials in the Materials List tab, each based on estimates of thickness and labeled these groups appropriately: “Half Thick Painting Calculations,” and “Crazy Thick Painting Calculations.”

I used four 3 x 3 inch canvases to do thickness tests with various acrylic mediums, looking for something that would be lightweight, hold good peaks once dry, and not shrink too much in the process. I taped up the edges of each canvas and got out a small measuring cup. I poured one ounce of Soft Gel onto one of the canvases, and did the same with Regular Gel, Extra Strong Gel, and High Solid Gel on the three remaining canvases. I allowed them to dry and cure for 1 week.

Minor segue: My developer and I spent many exhausting nights working on this project, and by now we had developed our own vocabulary for handling this information. Where “square inches” is abbreviates to “in2,” we wrote “sq/in” to avoid dealing with superscript type formatting. In discussion, we reduced “square inches” to a phonetic representation of our shorthand, resulting in a new word pronounced, “squin.” Likewise, fluid ounces were written “fl.oz.” and pronounced “flaws.” Thus, “Fluid ounces per square inch” became “flaws per squin.” /

After a week, I sliced into the surface of each acrylic pour with a utility blade to check the resulting thickness of the cured samples. I measured the depth of the cut with a mark against the blade, measured the length of blade from the depth mark to the tip, and converted that into mils. The sample that had retained most of its volume as it dried and cured was the High Solid Gel Medium, so we calculated for an entry in the Materials table for High Solid Gel at a 0.5” thickness.

From our tests, we determined that it will take roughly 0.3 “flaws per squin“ to make 1/2” of surface on a canvas. According to my spreadsheet calculations, I can expect a 32oz container of High Solid Gel Medium priced at $39.16 to cover 126 square inches of canvas with a layer that dries to roughly 0.5” thick. Knowing this, each of the painting thickness calculation groups in my Materials List is comprised of my best guess of the numbers of layers required to build up the surface of each grouping based on a less expensive gel medium that shrinks a bit in the drying process but will work well regardless.

Paint formulation relies of a wide range of natural and chemically produced pigments to make different hues of paint. As a result, the price of paint differs depending on the colour. Cobalt blue is one of the more costly paints, so I used a local supplier’s price as the paint price variable. Using soft gel acrylic medium to extend the paint and to create glazes, and including a prescribed ratio proportion of acrylic retarder64 to mix into the paint and gel medium, each thickness group had an individual set of equations to calculate the volume amounts and costs that I might expect from a painting of a particular thickness.

I have kept the 0.5” thick layer of High Solid Gel Medium entry and its corresponding calculations in the Materials List table for those special times when nothing else will do for building extreme texture and depth on a surface, but it is not factored in to the Half Thick or Crazy Thick Painting Calculation material groups by default.

Also missing from the Painting Calculation material groups are elements like exploration, sketches, form, an artist’s lifetime of experience, and each step that moves an artist closer to completing a work of art. I spent 4 months researching, discussing, asking around—generally embarrassing myself in front of anyone who would listen—while I tried to figure out a way to break down these elements of an artistic practice into something quantifiable. I have elected to leave that task to someone else at this time, because I don’t think it’s possible to do this. Therefore, the spreadsheet does not account for these factors and what would have been the “Art” layer will have to be measured in material thickness and expensive paint.

With the mystery layer resolved for the time being, I now had a method for estimating my material costs per painting. I soon wondered what these numbers would look like with an artist’s studio rent factored into the equation. How many paintings would a working artist have to produce and sell per month to cover all their home and studio responsibilities? I filled another tab with financial information, and my patient software developer expanded the spreadsheet so that all these factors were considered in the final prices.

When we finished the spreadsheet project, I cleaned up the formatting and renamed it “Burden of Proof.“ Although I had a tool that would dissect materials, crunch numbers, and spit out values, we concluded that we could not quantify the “value” of art in this manner, and I plead guilty for trying.