Made from roughly 80-90% crushed calcium carbonate stone rather than wood pulp, Karst's notebooks are genuinely waterproof and tear-resistant — coffee wipes off the page instead of soaking in, and the paper never yellows or dries out with age. Production uses no trees, water, bleach, or acid, and the stone paper carries a Cradle to Cradle Silver certification.

An expandable back pocket, ribbon bookmark, and lay-flat thread binding round out the format, available in hardcover or a flexible vegan-leather softcover, with blank, dotted, ruled, or grid page options.