Got a vintage pen recently that was supposedly restored. But the ink would run out after a few lines of text. I pulled out the section and found ink on the outer surface of the sac. Then I noticed the sac was barely attached, being kind of hitched up toward the top edge of the section. I wiggled it back down, but haven't tested it. I wonder if it wasn't making a good seal and this was interfering with the ink flow.

Isn't the sac supposed to be sealed? I recently bought some in order to try resacing my own pens, but haven't had time to try yet, and I certainly don't want to try on a nice pen.

As a stopgap (partly to verify the pen is otherwise ok): If the sac is really all the way down on the section, will it seal tightly enough to prevent air leaks?

Alternatively, can I get away with sliding the sac up almost all the way to the edge, putting some shellac below that, then sliding the sac back down?

Thanks!
/K

It should be sealed with shellac.

It isn't hard....go for it!

If you want to practice first, do it to an Esterbrook first. They are most forgiving. Trickiest part is stretching the sac over the end of the section without gunking up your fingers with shellac.

Bad for your fingers but the pen doesn't mind.

Andy

You must use shellac to "glue" the sac to the nipple on the rear end of the section. I say glue but do not use glue. Shellac is used because it is removable and provides a watertight seal. The sac itself will not provide a seal.
Be careful not to use too much shellac as it could get in behind the section and gunk up the feed channel if you're not careful. Bent nose tweezers or even better a sac spreader are ideal to help with this. You will also need to use talc powder on the sac so it doesn't stick in the barrel.
You could check out www.tryphon.it for shellac, tweezers etc..(no affiliation and there are other sources).
Gary

Ok, thanks for the pointers!
/K