Uni Liquid Chalk Markers utilise water-based pigment ink, allowing you to mark on windows, glass, mirrors, plastic, and metal surfaces with ease. The ink is rain-resistant, making them great for outdoor signs, but can be removed from non-porous surfaces with a damp cloth or mild detergent. The 5mm bullet tip is perfect for writing and creating smaller details, ideal for signs in pubs, cafes, and restaurants. These chalk-based markers are designed for signwriting on non-porous surfaces.