[stationery] this week in learnings
Nov. 26th, 2021 09:52 pmSilicone is not permeable to water, but does (or at least can) have significant gas permeability.
This is relevant to stationery because a lot of "vintage" fountain pens -- prior to about the 60s and 70s -- use ink bladders made of latex.
I have one such pen, currently without a sac fitted, and went down this particular rabbit hole while trying to work out what my best option for getting it up and running again is.
It turns out that fountain pens, much like one of my other terrible hobbies, are (variably) expensive vacuum leaks. What this means for vintage pens fitted with silicone sacs is that you must store them upright basically any time you're not writing with them...
... because otherwise the combination of capillary action (which is how the nib works) and gravity draws ink out of the reservoir. In a pen fitted with a latex sac, this doesn't happen because air can't leak into the reservoir -- but the gas permeability of silicone means that with a silicone sac it can, just by dint of the exterior of the sac being in contact with the atmosphere, so there's absolutely nothing to stop all of your ink deciding to Go On An Adventure, Which Is Widely Considered A Bad Idea.
Ergo I have decided that my mild contact allergy notwithstanding I think it is worth gloving up for long enough to fit a latex sac, which I will then never have to interact with directly again until it perishes, because the pen in question is a lever-filler (as seen on youtube). This will be my first attempt at doing any such thing, mind, so it's entirely plausible that I'll end up with an uncontrolled leak regardless, but hey -- fingers crossed!
(More detail if you want it!)
This is relevant to stationery because a lot of "vintage" fountain pens -- prior to about the 60s and 70s -- use ink bladders made of latex.
I have one such pen, currently without a sac fitted, and went down this particular rabbit hole while trying to work out what my best option for getting it up and running again is.
It turns out that fountain pens, much like one of my other terrible hobbies, are (variably) expensive vacuum leaks. What this means for vintage pens fitted with silicone sacs is that you must store them upright basically any time you're not writing with them...
... because otherwise the combination of capillary action (which is how the nib works) and gravity draws ink out of the reservoir. In a pen fitted with a latex sac, this doesn't happen because air can't leak into the reservoir -- but the gas permeability of silicone means that with a silicone sac it can, just by dint of the exterior of the sac being in contact with the atmosphere, so there's absolutely nothing to stop all of your ink deciding to Go On An Adventure, Which Is Widely Considered A Bad Idea.
Ergo I have decided that my mild contact allergy notwithstanding I think it is worth gloving up for long enough to fit a latex sac, which I will then never have to interact with directly again until it perishes, because the pen in question is a lever-filler (as seen on youtube). This will be my first attempt at doing any such thing, mind, so it's entirely plausible that I'll end up with an uncontrolled leak regardless, but hey -- fingers crossed!
(More detail if you want it!)