Handcrafted in small batches from black walnuts locally in Western North Carolina. Perfect for drawing, sketching, painting, dyeing, staining or calligraphy. This ink is made from organic black walnut shells that are naturally acidic. It's not waterproof, is water-based, can be re-wetted, and acts much like watercolor in use. Note: Not suitable for use in reservoir fountain pens. This is a natural ink that contains natural sediments that might clog the reservoir of a fountain pen. It's used with reed pens, dip pens, or a brush.