I just bought a Conklin Ohio and saw that cap thread is a bit scratchy. Does vaseline work?

I think most pen experts would recommend silicon grease for this job.

Ray

Silicone or talc should work.

A lubricant won't fix the problem, it will only mask it. My usual treatment for this is to remove the section, smear Simichrome on the barrel threads, and work the barrel and cap against each other to wear away the scratchiness. Back them all the way apart until there's a tiny click, from time to time, to change the thread engagement, and then continue. After a couple of minutes, clean both sides thoroughly, reassemble the pen, and test. Repeat if needed.