Sunday, January 20, 2013

A Word About (supposedly) Silicone Pen Sacs

Word in the fountain pen community says the silicone sacs we have been purchasing for years really are not pure silicone, they contain.... vinyl!  What's wrong with vinyl you might ask?  Much is wrong with is, not only is soft vinyl somewhat toxic (plasticizer leech, phthalates anyone?) it has the ability to melt and destroy other types of plastic, celluloid and polystyrene are amongst these and most pens are made of those.  You might remember this having happened with some your toys when you were a child, you haphazardly toss your toys in the toy box and a soft vinyl toy happens to come to rest on top of one made of a hard plastic.  You go on vacation for a week and come back to find that the vinyl toy has melted the hard plastic toy where they touched.  Or maybe as you grew up you stored some of your childhood toys together, hoping that someday you would be able to pass them along to another child?  Maybe you take that box down when you find out someone in the family has a kid who might enjoy those toys, only to find some of them have melt marks and gummy plastic, maybe a toy containing both vinyl and hard plastic parts is in the process of self-destruction (dolls and action figures with vinyl heads and limbs and hard plastic bodies).  It's not always a process that will take place over night or even over a few years time.  This is what can happen to your pens if you leave the vinyl containing sac inside, so it's best to remove them while there is still time.

Today I removed all the vinyl sacs from my pens and I didn't find any damage, which is good considering some of these sacs have been in a pen for about six years.

Right now the only place to buy pure silicone sacs is:   (no affiliation)

They are only available in limited sizes right now, but the proprietor is working on making other sizes available.

You might also want to watch this:

Suspect Silicone Sacs: removed from my pens, the one on the right looks suspect to vinyl deterioration
All of this makes me wonder if pen sacs could also be made from TPE.  It's a plastic that is used in medical devices and implants and looks and feels much like silicone.


  1. Hello. Nice to meet you. I'm Kota from Japan. ^^/ Wooow, nice and informative blog you have! I'm a member of The Fountain Pen Network. And I have my own YouTube channel about fountain pens, organizers, film cameras, and so on. If you have time, please take a look at the videos. I hope you'll enjoy watching them! I'm looking forward to your new post!! Have a good day. Kota Adachi

  2. Thanks for introducing yourself. I am also a member of FPN, if you didn't already know- many people find their way here through the link in my signature there.

    I'll have to check that out.