The 4500 Textile Marker offers high quality and excellent definition on many light-colored, chemically untreated fabrics such as cotton, silk and linen, as well as on a number of mixed fabrics. The applied ink can be made permanent by ironing once (without steam), the textiles can be washed at up to 140 degrees F (60 degrees C). The marker has a resistant 2-3mm thick round nib. The water-based pigment ink is quick-drying, extremely lightfast and has a neutral smell. For limited use only on polyester, as it can often cause the ink to run.