What are they for? Uni-Ball's POSCA paint markers are extremely versatile pens designed for colouring and decorative work. They are expertly designed for use on a huge variety of materials, including paper, card, canvas, wood, metal, plastic, ceramics and more. They can also be made permanent on some surfaces by heat treating them. For example, ceramics can be heat treated to create a permanent application. How do they work? The PC-8K range features a broad chisel tip, which has a built-in pump action mechanism. When you first begin using the pen, you simply press the tip against a scrap piece of paper or your project to deploy the ink. Once the ink starts flowing, you can draw and colour anything you like. The ink is water-based and very opaque. If you're drawing on non-porous surfaces like plastic or ceramics, you can sometimes also wipe away the design with a damp cloth in order to make corrections or adjustments.