Ulam Spiral Quilt

I've actually made some good progress on the writing I'm supposed to be spending 100% of my time on, so I am rewarding myself with another insane quilt: An Ulam Spiral. (You can read all about Ulam spirals at that wikipedia page.) This quilt was suggested by Dan Brumleve in a comment left on my Infinity Pi quilt blog post. (Actually he wanted an Infinity Ulam quilt, but I can't think of any way to do that, so I'm just making a finite version.)

Nina suggested representing each prime number by an in-and-out spiral, which looks cool, and should lay down enough thread to make the primes stand out. This pattern should stitch quite fast, because it's got a lot of straight lines in it.

I made two designs, low density (primes up to 1225) and high density (primes up to 9801). I am, of course, doing the high-density one first.

Here is the low density version, where you can see the individual spirals.

And here is the high density version I'm actually going to stitch. The lines will be about an inch apart.

I'll start it later this afternoon (Saturday May 7th, 2016 for you people reading this years from now). If you want to be notified when stitching actually starts, sign up for the StitchCam email list at the StitchCam page.

I'll post again when it's done and I have pictures of it.