Why is it not recommended using the Faber-Castell PITT artist pens on fabric?
The PITT artist pens are comprised of India Inks which are permanent and lightfast. The permanency and lightfastness are tested on paper. They are not tested on fabrics. If the pen is used on fabric it should be displayed as an art piece and not washed. Due to the nature of fabrics washing may cause the inks to fade.