My sketchbook is also a place to test out supplies and new techniques. Here I was drawing with a Hunt 102 mapping nib and Sumi Ink.
This is a test of a background technique that I'd done before but forgotten about. I scribbled water soluble markers on a baggie, sprayed it with water and then applied it to the page. You can also use food wrap or thinner plastic bags, an acetate sheet, acrylic block or craft sheet to do a similar thing.