Quink seems to be a reputable ink and is generally considered safe. The original composition used isopropyl alcohol as a solvent. This is known to dissolve nitrocellulose (celluloid, pyroxylin, et cetera), but was advertised to accompany the Parker vacumatic that had a barrel of exposed nitrocellulose. The advertisements for quink emphasized the harmlessness of the chemicals it was made from. The current recipe for quink, as I understand, contains no isopropyl alcohol, but does contain diethylene glycol, which is still a solvent to nitrocellulose.
I have come across a few posts which warn that quink or vintage quink can damage celluloid, but half of the time they seem to be confusing it with superchrome.
I have personally never seen celluloid pens that appear to have been dissolved from the inside out.
Is quink safe for celluloid pens? Has anyone come across damage from inks that are solvents to the barrel that they are held in? Do other inks contain solvents that dissolve nitrocellulose, but result in a neutral pH and pass other safety tests? Did Parker line the barrels of third generation vacumatics with a chemically robust plastic (as I have heard rumored)?
Any advice would be appreciated.