One thing I like about pen plotting is how crunchy the materials are. I’m used to doing generative art and graphic design on screen where all the lines are pixel-perfect and if anything you try to hide the pixels, too. Ink and paper are much messier. Paper has texture and fiber. Ink bleeds and flows unevenly. There’s different kinds of pen inks, pigments that sit on top of the paper vs dyes that soak into it.
But despite liking all that crunchiness I also want control. I am particularly frustrated with the dot you get when the pen is dropped on to a page as the ink blots into the paper. Different materials have different amounts of bleed, consistency, etc. Sometimes you want something that works pretty much like pixels on a screen.
For paper I like this Neenah Exact Vellum Bristol, 8.5″ x 11″, 67 lb/147 gsm. It’s good heavy card stock. Paper is nicely flat but has just a bit of texture so that a swift moving pen leaves a slight graininess. (It’s not polished paper). It’s pretty cheap too, about $0.04 a sheet, so I’m using this for sketches that I expect to throw away.
The other paper I’ve used is this generic 5×7 note card 80lb / 216 gsm. The paper is a bit more polished than the vellum. I haven’t looked at cards too closely, mostly I just liked it came with matching envelopes and in small quantities.
Pens are a much bigger fun topic. I’ve tried lots but my go-to for basic solid line work is the Sakura Pigma Micron 05. My favorite thing is the very clean line it makes. Seriously looks like magic coming out of the pen, a solid smooth line. Almost no pooling / dots at the start or end of a line. I’ve never seen it smear or soak through heavy paper. The pens work great in a vertical orientation and ink flows cleanly at 50% speed on an AxiDraw; 75% starts being a little too fast. They come in a reasonable variety of colors, 15 in all, although the palette is a little heavy on the dark colors. The ink is advertised as archival quality. The 0.45mm pen (size 05) has the most color options and the line genuinely seems about 0.45mm thick. Parallel lines spaced 0.4mm show just a bit of white paper through, 0.3mm parallel lines make for a nearly solid color.
(I should disclose I’m a noobie to the pen plotter world, only been playing around with it on the side for a few months. There’s lots more to learn about materials!)