Product Description Higgins Eternal Waterproof Black Ink: A permanent dense black, carbon writing ink. Excellent for calligraphy, fountain pens and airbrushes. In a 2.5 oz. bottle. Please note: In our research, the Eternal is not reliably waterproof. It is ‘permanent and non-fading’ but it is recommended for fountain pens which belies the ‘waterproof’ element. In our opinion, it should be considered ‘non-waterproof.’