Until the early 20th century, the ink in a fountain pen was kept directly in the barrel. The slim barrels were made of hard rubber, which came in two colours, black and red. Ink was put in these barrels with an eye-dropper. To do this, the user had to take off the nib section, put the ink in and replace the nib section. This operation required a quiet secluded place, which some people might not have.