Unless you happen to have a ton of cartridges lying around, converters are probably your Huckleberry. They allow you to use bottled ink, saving some cash as you go. More importantly, they free you from the rather short color menu that cartridges offer.
Like anything man-made though, these small machines have their quirks. I limit this post to converters currently available from the Japanese Big 3 as these are the ones I have the most user experience with.
Pilot/Namiki currently make three converter models. The CON20 is a pressure bar variant while the CON50 is their rendition of the ubiquitous twist piston filler. The CON70 is a unique pump widget that is different from any converter I have seen before.
Of the three, the CON70 holds the most ink. It is however, a royal pain to flush. Disassembly is ill-advised and reassembly rivals a dice roll. If you are monogamous in your ink choices, this is of little consequence. Those who suffer from ink ADD might want to skip this one.
The CON50 is easier to manage but has its own shortcomings too. First, it holds an almost pitiful amount of ink. If Fines are your poison, this is not going be an issue (though you may want to top off daily.) Wider nib sizes make a travel pot of ink a really good idea.
Getting a full fill is challenging, as the thing seems to breed air pockets at will. Also, ink clings to the chamber walls which creates flow problems at the most inconvenient time. New releases incorporate a metal nipple that agitates the ink to ensure an easier fill and a more reliable flow. Having used both versions, I find that the newer iteration works better but is still far from optimal.
Lastly, it does not tolerate disassembly very well. The threads that mate with the rear coupling tend to strip easily and I realized this after going through 4 converters in just under two months. Not very inspiring.
The CON20 is the least expensive of the lot. You can’t see the ink level so you have no cue that you are running low. It holds less ink than a 70 but a bit more than the 50. The simplicity of the 20 makes it a breeze to clean and dry. I have not had any issues with it and it is what I recommend if you value stress-free living.
Sailor make but one converter type, a twist piston filler with a translucent ink chamber. Their plastic seems softer, more pliant than what the competition employs. Almost low rent, to be polite.
The rear is too easy to remove for cleaning, as only a suggestion of pressure is required to unscrew the coupling. Keeping this joint tight is a must and a bit of silicone grease is cheap insurance against leaks.
With the Sailor, the piston seal seems to be the weakest link. In the ones I’ve had, ink would always creep past the piston seal during filling. It did not affect flow in any way but I was more concerned with ink eventually trickling out from the rear. Not the most robust converter in my opinion but it works adequately.
Platinum/Nakaya also employ a twist filler converter. It comes with a clear ink chamber and like the Sailor, it will hold more Iroshizuku than a Pilot CON50. The tail end takes a fair bit of pressure to unscrew but all threads seem to hold their fit despite regular field stripping. The piston seal is good and I have yet to get unexplained air pockets or see ink loiter behind seals.
Its Achilles’ heel is where it mates with the pen. Within a gold-colored collar is a white plastic bushing that slips over the rear of the feed. This bushing wears over time, and once it loses grip, the converter will not stay seated for long. The slightest tap or shake can jar the whole thing from the feed’s nipple.
The intuitive solution would be to make the bushing out of a hardier material. However, this might wear down the nipple instead. Converters are easy to find. Feeds are a different matter.
Looking at all these quirks, I begin to wonder if the Japanese actually favor cartridges over converters. After all, I never suffered any of these headaches using their carts.
Whatever their design predilections may be, knowing where these micro-machines can fail allows us to solve their problems before they begin.