So I recently stumbled across a Fountain Pen set whilst doing some cleaning. It is a Osmiroid brand, with five nib units. I'm now in possession of it, but have no ink for it, nor ink cartridge. Is it possible to use any other ink with this, and if possible, could someone recommend me a quality, yet relatively cheap ink brand.
NB: The manual states not to use any spirit based inks, so yeah.