Wahl Cap Discoloration: Why That Banding?
[The PENnant, Spring 2002]
The manner in which vintage celluloid pens discolor varies considerably. Much of this variation is due to construction methods: button-fillers such as Parker Duofolds, for example, are typically found with much worse discoloration in the barrel than in the cap. Their tightly-sealed barrels do not allow free dispersal of the reactive deterioration byproducts of the rubber ink sac.
One of the most unattractive discoloration patterns is found on Wahl pens of the later 1920s and early 1930s. In addition to the usual barrel darkening, there are typically prominent bands of discoloration on the cap above and below the inner cap, as is well illustrated by the photo above.
Why these bands? Unlike most penmakers, who were content to use simple inner caps of plain hard rubber, Wahl chose to use a composite construction that seemed to offer a better seal. The inner cap proper was a conventional hard rubber tube, but it rested against a stiff rubber disk which closed off its upper end. Unfortunately, while hard rubber is quite impervious to most chemical action (at least as long as it is not exposed to light), the disk is of normal rubber that is far more vulnerable; in most cases, ink and air and moisture have broken it down, releasing the same sort of reactive sulfur compounds released by aging ink sacs – and releasing them in a tightly-closed area where they cannot easily escape.
Copyright © 2002 David Nishimura. All rights reserved