Update: I mentioned that you can use any ink in the pens. But you should keep in mind that if it's an ink that dries and clogs naturally on it's own when left out, then you would expect some clogging to happen, especially on the crowquill nibs. The chinese ink clogged it. But since the parts of the pen could be dismantled, I washed it off, filled it with fountain pen ink and it's working again.
Update: I mentioned that you can use any ink in the pens. But you should keep in mind that if it's an ink that dries and clogs naturally on it's own when left out, then you would expect some clogging to happen, especially on the crowquill nibs. The chinese ink clogged it. But since the parts of the pen could be dismantled, I washed it off, filled it with fountain pen ink and it's working again.