Another seive of Eratosthenes

eratosthenes 7

Yeah more prime numbers baby!

So if you saw my previous post about the seive of Eratosthenes you might have seen some other versions of this painting.

Let’s recap, the seive of Eratosthenes is an algorithm for finding prime numbers. You have a grid with each cell numbered, start with two and cross off every 2nd cell as it is divisible by 2 and therefore not a prime, then the third cell is clear so cross every 3rd. The 4th cell is already crossed off so ignore, cross off every 5th ad infinitum.

So I did a couple of these and had them hanging on my wall, then sold them and found I missed them. So I did another one. This time there are 17 squares across so we get a slightly different pattern forming. I was spent a lot longer preparing so when I came to paint I could focus on the paint and not worry about where the numbers were.

I’ve been learning python and javascript and mathematica, but I’m not proficient enough just yet to write a code to do work all this out for me yet, so back to good old spreadsheets yeah! I could format each multiple of a prime number to be a colour and the next one to increase the amount of red by 5 (or green when the red got to 255). Then I exported each array of prime numbers as a layer in Illustrator so I already had the plan before seive

You may notice the similarities, but if you ask me it looks far too clean like this and resembles a bus seat. From the previous paintings I knew how I wanted to apply different layers of paint onto numbers made of multiple prime numbers so I wouldn’t get this cleanliness also avoiding totally straight lines. The pigments I used for the painting had different oil absorption rates which results in some squares having a slight satin or even glossy feel, or a rich velvety quality, ooh yeah its nice. So that’s why my painting is more sparing with the bright colours and bus seat pattern, keeping that velvety paint. It did involve making a lot of paints that were only a tiny bit different from each other, but thanks to having it all mapped out before hand was a lot less confusing than some of the other versions.

It’s pretty big by the way 40″ by 52″ including the frame.


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