I tested Diamine Imperial Purple in a reused Sailor cartridge before putting it in a demonstrator, and the result was a stained cartridge. I love the color, but I haven’t had any luck getting it out of my cartridge with water, soap, a little bit of ammonia, and time.
I don’t write much, so a pen could stay inked up for months on end.
Is there a way to get this color out of plastic? Is it safe to use in converters and demonstrators without staining them too?
My go-to in cases like this it to just step up the solvent-molecular-weight scale until you either A) get the desired result, or B) destroy whatever polymer the thing is made out of.
I don’t know about ammonia, but isopropyl alcohol seems to dissolve all the constituents of every dye based ink I’ve ever tried it on, which ought to encompass all fountain pen inks – and also inkjet printer inks, for what it’s worth.