Provided the ink is labeled as "fountain pen ink", you can use it in your pen. But, remember, it has to be labeled "fountain pen ink". If it isn't labeled "fountain pen ink", it will probably cause you some grief: from clogging up the feed to causing damage to internal seals.
India ink is not fountain pen ink! Using India ink in a drawing pen (like a Rapidograph) is perfectly ok. But, don't use it in a fountain pen, unless you want to have a premature experience with nib and section disassembly!
Also keep in mind that all true fountain pen inks are water soluble. If it isn't water soluble, don't even consider using it in your pen.
We sell quality engraved pens and custom pen sets $50 and up. We have the largest selection of nice engravable gift pens and presentation pens including Waterman, Waterford, Parker & engravable fountain pens. The best custom gift for an associate, a friend, or yourself is something used everyday - a pen! We do not cheapen our pens by laser marking or surface printing, we customize our fine pens and pen sets with 'jewelers' quality machined engraving. So if you want quality engraving or a logo on that special pen from Waterford, Waterman, Parker and more in quantities of 1 to 500pcs Then you have found the right store.
