Goldfaber Sketch Markers contain alcohol-based, dye stuff inks that are fast-drying, water-resistant, smudge proof, acid-free, pH-neutral and permanent once dry. Colors blend easily without streaks. Layer colors to achieve opacity and create stunning gradients, transitions or 3D effects. The sustainable and versatile sketch markers contain dual tips – a soft, flexible brush nib for vast coverage with variable line widths of 1-5mm on one end and a metal-encased 0.6mm fineliner tip for contours and details on the other.