Could someone recomend a blue, blue/black international cartridge with a very smooth ink? I use Waterman in my piston fillers and they don't make an international size cartridge.

How 'bout refilling your international size with a syringe and the Waterman you like. I do that. Got the syringe from my vet, tho' some state allow you to get from drugstore without any Dr approval.

I've also picked up some international size converters to use in place of the cartridges. But some pens need a slightly different international size converter making life ... interesting.

PS I love mixing waterman inks and the syringe and converter or cartridge are great places for mixing.

What do you mean by all of this? Unless I'm mistaken, Waterman is one of those which makes an "international" cartridge. I'm able to use both long and short Waterman cartridges in my S.T. Dupont pens. I'm using a Waterman convertor in my FILCAO Leader pen. Not to mention, I've just checked Pendemonium's site, and they also list Waterman as one of those that uses / makes International cartridges.

http://www.pendemonium.com/ink_facts.htm#cartridges

Waterman makes "long (standard) international" cartridges. There are also "short international" cartridges, which seem to be the most common these days, but as far as I know, Waterman does not make the short ones.

The "nipple" is the same on both types, and they are the same diameter, so they are compatible as far as inserting the cartridge into the little spike in the section. However, some pens may have a shorter barrel that will not accomodate the longer cartridges.

(addendum....hmmm...upon further exploration, it appears that waterman makes "waterman lady" cartridges, which are an inch and a half sized mini-cartridges. I am not sure what the nipple connection looks like on these, however. If it is the same, I would suspect it would fit as a short international cartridge substitute. However, I have only found black and blue as available colors.)

Waterman makes European standard cartridges, both short and long. I believe those are also called international size.
I asked about these Waterman cartridges some time ago. See the thread with topic title "Does Waterman make short cartridges?" here in "Inky Thoughts."
(Sorry I do not know how to insert a topic link because I do not know the ID#. Incidentally, where do you find the topic ID# of a topic?)
You will find lots of info in that topic, as well as references on FPs that take the cartridges.

They can be bought on eBay at very good prices. I bought some just today (see #250102338527, but also several other sellers). I have been using these cartridges in a MB without problems. I also used them in a CS.

Jea