Noodler’s Bulletproof Black is a best-seller among our hundreds of ink colors. It’s waterproof quality makes it reliable for doctors, lawyers and business people to write on secure documents. Artists can lay down their linework in bulletproof black and then put washes of watercolors over the black without washing out the ink. The formulation resists forger techniques so you can securely write on checks and other important papers.Bulletproof Black permanently attaches itself to the cellulose of paper fibers, while being able to wipe cleanly from your pen when performing routine maintenance. 3oz (89mL) of fountain pen safe ink.