*** I only officially accept Eureka ultem ink cartridge as main ink storage device for my pens.
I no longer officially recognize Con-70 / Con-40 as main converter for Eureka fountain pen models.
Although they are still compatible, you must read con-70 related manuals / tips before using them.
It is tricky to get it right, although if you are skilled / experienced with the system, it is possible.
For those having difficulties , I recommend the machined ultem cartridge instead.
please note that because of the way Con-70 was produced, external surface is not consistently accurate between batches / not perfectly round.
So some of them may require "taming" by wearing the external surface down to match eureka grip part.
This is only problematic for fitting into eureka grip section, which uses external surface to seal (as opposed to internal surface).
For some people it was very difficult to install Con-70 all the way.
below is an example of wrong installation:
it needs to be pushed in further.
to do that easily,
simply empty the ink converter,
then push the end against the floor / desk (protect the surface with some paper, if needed).
use two hands if necessary, although you don't want to apply extreme pressure.
because a large force can be applied, even with one hand.
below is the correct installation photo
(you will have to install the o-ring, please check inside with a flashlight).
there should be around 0.7mm space outside as the oring gets compressed.
*for ebonite grip sections, it is not necessary to insert the con-70 all the way.
ebonite is more flexible and made from natural rubber,
so it will seal better than peek / ultem material.
the opening of the con-70 will push firmly against Oring inside,
and this will assist the seal.
Thanks to this research,
with the periodic replacement of the internal o-ring / converter, this sealing system will last very long.
