These Uni POSCA PC-8K Poster Markers have water-based pigments which can be blended when wet or overlaid when dry. They have a chisel tip which can produce thin lines on the point and thick lines on the side. The ink will come out opaque every time and will not fade over time. The chisel tip produce a line up to 8 mm wide depending on the angle you hold it. You can blend these markers when they are wet or overlay them when they are dry. The water-based pigment ink is permanent on porous surfaces but can be removed from glass. The markers have a round, easy to grip barrel. You can use them to mark on paper, metal, glass, fabric, minerals, canvas, ceramic, wood and plastic. The lid colours match the ink colour to help you find the right marker. This pack contains 4 markers in black and white. POSCA tips can be removed and washed by rinsing it under cold water or leaving it to soak overnight. The ball inside the barrel mixes the paint, giving an even consistency, while the cap provides a tight seal ensuring protection and longevity of the tip.