Refilling a Crescent Filler is simple: Depress the crescent into the barrel of the pen while the nib is submerged in ink. As you release, ink will be drawn into bladder of the pen. Repeat the process a few times to fill the ink sac completely. Once you have filled the pen, wipe off excess ink from your nib with a soft cloth or tissue, then rotate the locking ring underneath the crescent to closed position so that the ring opening is on the opposite side if the crescent. The same process can be used with cold water for cleaning, and the crescent itself also helps to prevent the pen from rolling unnecessarily when in use.