I doubt the graffitist was thinking about the weight of paper when they altered this ‘no standing’ sign, but in my world, GSM stands for ‘grams per square metre’, and is the standard of paper measurement that allows people who work with paper—printers, designers, artists, bookbinders, etc—to know exactly what they’re dealing with in terms of thickness. This week I replenished my paper supplies with two of my favourite papers: Stonehenge White (245 GSM) and Zerkall Laid (120 GSM). Stonehenge is a machine-made fine art paper with a smooth surface, made in the USA, and Zerkall Laid is a German paper with irregular wavy laid lines. I like them because I can draw and paint on them, print on them, cut them up, fold them, glue them, and I can put them through my inkjet printer and get the result I want before I fold them and bind them.