The Nitty Gritty of Dirty Pens
If any ink, not just permanent ink, dries in a piston-filler or twist-converter pen, it will harden, and when the user twists the filler knob, they may drag the piston across the inner surface of the reservoir, ruin the piston or scratch the inside of the barrel or converter.
In case you are working with dried ink, we recommend using household ammonia, which will break down most non-permanent inks so they can be flushed.
Dried permanent ink is very challenging to remove and is most times a repair job.
Avoid using alcohol, paint thinner or lacquer thinner when cleaning ink from a pen.