PITT Artist Pens feature pigmented India Ink that is both acid-free and archival (pH neutral). Offers unsurpassed lightfastness. Perfect for sketches, journals, cartooning and fine ink drawing. Available in classic fine art colors: black, sanguine and sepia. 4 nib styles: superfine, fine, medium and brush. Ink is smudgeproof and waterproof when dry.