Description Ziller Periwinkle Blue dip pen ink is a muted shade of blue that leans toward purple, and is pH balanced, lightfast, waterproof and pigmented. The 1oz glass bottle has a square base which keeps it stable while open and in use. Ziller dip pen ink is for use with for dip pens ONLY. DO NOT use with fountain pens, as it can permanently clog them. We offer Free Shipping on all orders over $50 for US customers, and for orders over $250 for our Canadian customers.