A large canvas transferred from a 9X12 sketch. |
When working on a very large canvas in a normal-size room, I
start with a smaller sketch (either in oil or graphite) and scale it up. There
just isn’t enough space to stand back far enough to draw directly
on the canvas.
I realize many artists are math-phobic, but there are times when an eensy-weensie bit of arithmetic can save you a lot of work. I'll try to make this painless.
I realize many artists are math-phobic, but there are times when an eensy-weensie bit of arithmetic can save you a lot of work. I'll try to make this painless.
The first step is to work out whether the aspect ratio of the sketch is the same
as the canvas. This is the proportional relationship between height and width.
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Usually I grid in Photoshop because it's faster and I can just delete the lines with a keystroke. But you can grid just as well with a pencil on your sketch. |
Sometimes this is very obvious, such as a 9X12 sketch
being the same aspect ratio as an 18X24 canvas. But sometimes, you're starting with a peculiar little sketch drawn on the back of an envelope or something. You can use a trick you learned back in elementary
school.
Remember learning that ½ was the same as 2/4?
We want to force our sketch into a similar equivalent ratio with our canvas.
Let’s assume that you’ve cropped your sketch to be 8”
across, and you want to know how tall your crop should be to match your canvas.
Write out the ratios of height to width as above.
To make them equivalent, you cross-multiply the two fixed
numbers, and divide by the other fixed number, as below:
Use your common sense here. If it doesn't look like they should be equal, you probably made a mistake. And you can work from a known height as easily as from a known width; it doesn't matter if the variable is on the top or the bottom, the principle is the same.
The next step is to grid both the canvas and sketch. You
could spend a lot of time calculating the distances, but I prefer to just
divide it in quarters in each direction. I use a t-square and charcoal, and I’m
not crazy about the lines being perfect; I adjust constantly as I go.
The last step is to transfer the little drawing, square by
square to the larger canvas. I generally do this with loose paint, in raw
umber. It’s time-consuming, but with big paintings it saves a lot of work in
the long run.
Let me know if
you’re interested in painting with me in Maine in 2014 or Rochester at any
time. Click here for
more information on my Maine workshops!