It is difficult to estimate how long newly-replaced cork and rubber seals and rubber ink sacs will last. Certain inks seem to be harder on sacs than others, and there are also significant variables such as temperature, humidity, and levels of pollutants such as ozone. Nonetheless, it is worth noting that one still finds many Esterbrook lever-fillers from the 1950s and 1960s with usable sacs; the same is the case for Sheaffer Snorkels of the same vintage.
Judging from empirical evidence, it would seem that rubber sacs should be good for at least ten years and may well last for much, much longer. Cork seals, whether in piston or pump fillers, or in safety pens, should last at least as long, and the special vinyl sacs used on Parker Aerometric fillers would appear to have an average lifespan in excess of 50 years.
Copyright © 1997-2008 David Nishimura. All rights reserved