I was told by a reputable vintage pen shop that posting a cap on a vintage pen, such as long striated pattern Parker Vacumatics, Duofold, etc, makes the cap prone to splitting since it is made of celluloid. They said it is a good practice not to Post A Cap on a vintage pen when using unless there is a nylon other insert that is for that function and it is mounted deeper into the cap. However, a lot of pens don't sit very well in the hand when writing if there's no cap. i have a number of expensive vintage pens that I write with, a lot. What is the solution? Buy a sacrificial cap? *PS: I am not a collector. I own pens for a quality and uique writing experience. So, "writeability" it important to me. Thanks for the help. jim