Yes, waterproof fountain pen inks are availiable, and they cause no issues in a pen with a reasonably airtight cap that is used regularly. However, they can clog a pen when they are not used for a few weeks or in very hot weather outdoors. Those clogs are hard to remove because they aren't water soluble and have ruined feeders or whole sctions before for me. I hope this pen will eliminate those problems, so i seriously consider getting one.