|Filling Instructions: Crescent-Fillers|
The crescent-filler is most closely associated with Conklin. To fill a crescent-filler, the C-shaped hard rubber lock ring must first be turned so that its opening is under the crescent. The crescent is then pressed, flattening the ink sac. Put the nib in ink, release the crescent, and count to ten to allow the sac to inflate.
In addition to the true crescent-fillers, there were numerous similar mechanisms designed to evade the original Conklin patents. All operate in much the same way, with a protruding piece connected to a rigid pressure bar inside the barrel which bears upon the sac, and some sort of locking device that turns or slides to prevent the protrusion from being inadvertently depressed.