Students can test different types of ink to see how they flow through the tip of a felt-tip marker. Fill up a reservoir with paint or other types of liquids that make marks on paper. Connect this reservoir to a tip of nylon or felt and allow the liquid to flow through into the tip. Test to see how quickly and consistently each type of liquid flows.
Students can also test different types of fibers to determine which move ink most effectively. They can use different methods of gauging the effectiveness of ink movement. These might include the time it takes for ink to move from a reservoir to the page, the angle at which the fibers absorb and move the ink, and how long it takes for the fibers to dry out.
Students can test to see what kinds of liquids help prevent the felt-tip marker from drying out. Test the marker tip by making a mark on a piece of paper, dipping it in each liquid, then leaving it overnight. The next morning, make another mark on the paper using the same amount of force as the day before. Determine how much the marker has dried out. Repeat the experiment using a different liquid to preserve the ink or renew ink flow in the tip.
Students can test different sizes and types of ink reservoirs. They can create a large reservoir and place a lot of ink inside it, and they can create a small reservoir and use a pipette to place ink inside it. Test what size of reservoir creates an ideal amount of ink flow to the page. Conduct an experiment to see what reservoir angle is best for maximum ink flow.