PITT Artist Pen Big Brush Pens contain four times the amount of lightfast, acid-free pigmented India Ink as the PITT Artist Pen, offering great coverage for work in large formats. The ink is smudge-resistant and waterproof when dry. The Big Brush Pens have a strong, big, nib for wide full strokes and narrow detailed strokes. They are ideal for sketches, journals, cartooning and fine ink drawing. Available in brilliant bold colors that are blendable, yet permanent when dry.