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Archive for January 5th, 2011

The Waterman Job

Posted by Dirck on 5 January, 2011

Yesterday I returned that Stalwart I spoke of on the last day of the previous year.

I think it’s fixed.

The problem as stated was this– the ink would slowly migrate from the reservoir into the cap, and soak the user’s hands when the pen was attempted to be used.  The assumption I made, as referenced on the 31st, was that the sac had some sort of subtle leak in it.  That’s what produces that kind of effect, after all, since I was able to rule out wild variations in temperature and atmospheric pressure.

But… there should have been some kind of evidence of the leak inside the barrel, too.  There was nothing at all.  The matter bore some investigation.  After a great deal of effort, including lowering the sac and section into a cup of water and trying to produce bubbles, there was still nothing.

This leads one to ponder misdirection.  If the problem isn’t down the inside of the pen, perhaps I should attend to the cap.  I have not quite played fair with the reader (were this a mystery novel, this is the point at which you fling the book into a puddle) for I have left out the important clue.  When I got the pen in hand initially, I took the cap off, and the inner cap dropped out.  “Well, that needs to be addressed,” I said to myself in a tone indicating that it was an afterthought right from the start.

Chorus:  You dummy!

The inner cap is a thing you tend not to think about too much.  It’s a little tube which is meant to seal against the face of the section, and most commonly it comes under consideration when it’s interfering with some other repair (concealing the mounting of a clip, for example).  There’s expensive gizmos to pull them free.  They’re meant to stay put.  One that drops out is inconvenient, but it doesn’t call attention to itself as a source of a leak.

Once the thinking cap was applied, though, I believe I found the mechanism of disease.  The inner cap is a seal, right?  If you look at the cap of an old pen, you’ll see vents drilled in– I have an ironically rather modern example here in which one is easily seen:

The point of this is to allow air into the cap while the threads are still engaged.  Without the inner cap, you wouldn’t need the vents, because the cap would be entirely sealed… but the vacuum caused by the extention of the sealed area during those moments of uncapping when the threads still hold tends to draw ink out of the feed, and eventually onto your trousers.

In the case of the dribbling Stalwart (does that not sound like a Hardy Boys title?), what appears to have happened is the inner cap followed the section on its way out, occluding the vents at exactly the time when they were most needed.  It wasn’t a slow leak but a sudden last-moment gush.  I was having trouble replicating the problem because, having been told I could expect a gusher, opened the pen with the cap lower-most.  The inner cap stayed where it was supposed to, and nothing untoward happened.

So, the inner cap is cleverly refitted to its correct place, the problem seems undone, and the pen is home.  The owner has been enjoined to let me know if the issue recurs.  I think I’ve learned a lesson on this pen, but it may be that I haven’t yet learned the right one.  Time will tell.

Today’s pen:  Waterman 52
Today’s ink: Pilot Iroshizuku Fuyu-Syogun (the grey one, in honour of the complete lack of vitamin D in my system)

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