Esterbrook Sac Problems

I replaced the sac on my Esterbook a little over a year ago. This week it started leaking, which was surprising because it had never leaked before. I pulled it apart today to have a look expecting to find a hole or tear in the sac. What I found was the sac had, for a lack of a better term, melted! It was just this really sticky blob of goo.

I have always been very good at cleaning the pen and have always used trusted FP ink. Mostly Noodlers Dark Matter.

Does anyone have any thoughts? Could it be the ink, or something else? I'd like to figure this out before changing the sac again.

Thanks in advance.

Not an entirely uncommon failure when using that brand. There are threads all over the internet arguing the cause of this type of occurrence and there seems always to be a common factor.

I wasn't convinced until ... http://badgerandblade.com/vb/showthread.php/307641-Melted-ink-sac-gooey-mess!

Time to revisit your trusted ink list.

I haven't heard Dark Matter as being one of the inks associated with sac and feed problems, but since it's the ink you used the most, the association seems plausible. Pelikan Brilliant Black and Aurora Black are two well regarded black inks with few problems reported. Good luck.