Modified Ink Converters
for Pilot Double Spare Fountain Pens
and Platinum Pocket Size Fountain Pens
and Sailor fountan pens.

Some old Pilot fountain pens such as the Capless (Vanishing Point) models take the old Pilot ink cartridges that were discontinued in the 1970s. These old ink cartridges were shorter and narrower and had smaller openings. You could actually put two cartridges in the Capless cartridge holder. These were officially designated "Double Spares" by Pilot.

Because the mouth diameter of the old and current cartridges is different, old model Capless pens require these old cartridges. These cartridges have become as rare and valuable as the pens themselves. Fortunately, Pilot has created a special squeeze converter called the CON-W that fits double spare pens. Unfortunately, these are very hard to obtain, and Pilot seems reluctant to sell them to just anyone.

I've been using a CON-W in my 1965 Capless pen with no problems, but recently when I went to refill it I noticed the rubber sac had detached from the plastic blue opening (maybe it would be called a nipple) and had bunched up inside the metal tube. So I took it all apart (apparently they are held together with friction and not glue). It would be simple enough to glue the original Pilot rubber sac to the blue nipple with clear nail polish, but I decided to use a regular number 12 rubber sac because I have a lot of them and I never seem to use them often because of their slim size. I could have used a number 16 sac, but the fit was a bit snug, and I thought the function might be hindered. Still, it would have probably worked. A size 14 sac would work as well, but I didn't have any.

The size 12 sac works well, and there is more space for it to expand and empty out than there was before.

Here are some ideas for those who can't obtain a CON-W converter for their old Pilot pens. I've also included a few ideas (some that were sent to me) for working with other makers' converters.

Pilot converter using ink sac

The first simply involves cutting the back end off of an empty Pilot "Double Spare" cartridge and gluing in a size 16 silicone or rubber ink sac. The sac will fit snugly inside the cartridge, so you can glue down a large area of the sac for better leak prevention. Glue it in place with some glue that works well on plastic and silicone or rubber. Before you start gluing, you'll have to trim the sac to fit your pen.

Naturally, this simple solution will work with many different types of cartridges if you find the right size sac. They are not as efficient as bulb fillers with a breather tube, and will not fill up completely, but they do get the job done.

Pilot converter using a Pilot CON-20 converter

The second solution requires a modern Pilot CON-20 squeeze type converter which is easy to obtain. Simply cut off the lip of an empty Pilot "Double Spare" ink cartridge and insert it into the lip of a Pilot squeeze converter. It is a snug fit, but you'll still need to glue it in place with some glue that works well on plastic.

Please note that this modified converter will not fit in all Pilot Double Spare pens, particularly some Capless (Vanishing Point) models. You have to check if your pen barrel is long enough to accomodate a Pilot squeeze converter first.

Platinum converter using a Pilot CON-20 converter

Many Platinum fountain pens out there are the short pocket size type that were popular in the 1970s and 1980s. Platinum used to make a short aerometric squeeze type converter that fit these pens, but they no longer produce it.

I went to Platinum headquarters once to search for some, but they told me these converters are all gone! Platinum still makes their long piston converters but they will not fit these pocket size pens.

I have one original Platinum short squeeze type converter, but I'm not letting go of it.

For those who are bent on having a converter for these pens, here is one solution. Please note that this modified converter will not fit in all Platinum pocket size pens, since it is slightly longer than the original Platinum short converter. You have to check if your Platinum pen barrel is long enough to accomodate a Pilot squeeze converter first.

Simply cut off the lip of an empty Platinum ink cartridge and insert it into the lip of a Pilot squeeze converter. It is a snug fit, but you'll still need to glue it in place with some glue that works well on plastic.

Note: This above solution will also work with a Sailor cartridge. It's a tight fit, but it will work.

Platinum short converter using a Platinum long converter

Here is an idea that was suggested by Margana Maurer who heard of it from Dillon Ang, pen repairer and proprietor of Dillo Ink and Pen Shop:

Look at this photo of a Platinum ink cartridge compared to a Platinum ink converter. They are the same width, but the turning knob on the converter makes it too long for the short barrel of a pocket size pen. We must find a way to shorten the converter. (The cartridge just fits the barrel.)

You can unscrew the brass covering, revealing the piston rod and the turning knob.

Simply remove the turning knob and replace the brass covering

Now the converter is only slightly longer than a cartridge.

Using the turning knob as a key, insert the small end in the brass covering, grab the piston rod and move it by either turning it or simply thrusting it in or out.

The only problem I've encountered with this is that the piston rod cannot be extended all the way, or it will be too long for the pen barrel. You can snip it (probably something you will regret someday) or simply don't fill the converter all the way. When you screw the barrel back on to the pen it will push the center rod back to the proper position -- and also expel ink, so remember to do this over the ink bottle!

Sailor converter for slim pens using a standard piston converter

(Note the solution using Pilot squeeze converter solution above will also work with a Sailor cartridge)

The metal covering for a modern Sailor piston converter will also unscrew, but I found it was too wide for use in a Sailor short pen. However, one person did find a way to use the converter without the metal piece in his Sailor trident, and I would assume the solution would also work for a short pen. Here is his message and photo of his converter:

Dear Russ

I got a sailor trident as I wrote before the body is narrow to accommodate the original converter, then I use the technique that you explain in your page and unscrewed the metal ring, put glue in the bottom and it is working

thank you very much


There is a small plastic disc in the end of the converter through which the center rod slides (on the right side in this photo). When you remove the metal piece, the disc becomes loose and moves with the rod, but the glue secures it in place.

Sailor short converter using a standard piston converter

Dillon Ang, pen repairer and proprietor of Dillo Ink and Pen Shop also sent me his solution for making a Sailor short converter:

I am currently working on a solution for the short pen converters for the Sailors. The Sailor short converter was made so that when it was inserted, only the plunger rod top would show when fully retracted. It is a very short converter and tends to have a problem with ink sticking in odd places. When in use, the converter needs a small metal or plastic ball inserted into it so that the rolling of the ball would break the surface tension of the ink. You have to pull the plunger rod to remove the converter.

When gluing plastic parts, I find Gorilla Glue useful I used Gorilla Glue to glue the little white plug on the sailor converter to the body of the converter. I was able to successfully use it in my pen. The ink capacity is the same as that of the original short piston converter. You just need the metal ring that comes with the converter in case you need to remove the converter, and be sure to mark the stem of the converter (Pilot paint marker?) so that you know how far to pull it out.

Update, July, 2008:

Dillon has sent me a photo of his latest modified Sailor converter that has the metal part and which will fit a pocket size pen:

He says:

This solution requires me to fit every converter into the short pen by hand. It works very well, but it's still too expensive. It can be used like normal Sailor converter and holds almost the same amount of ink. It takes at lot of work to do and I cannot do this to every pen because of size restriction, so the price is so high that it is embarrassing. It can be removed like any other converter to use cartridges.

If anyone out there has found a new converter solution or improvements on the ones already described here, please send me a description (a photo would be nice, too!) and I will add it to this page.