Indian ink pens are fountain pens contain India ink, a classic older form of waterproof ink that occasionally clogs and keeps the pen from writing. Cleaning your pen thoroughly once every four to six weeks will keep it from clogging. If you wait too long you may end up needing to send the pen to a specialist, which can be expensive and take weeks.
Take apart your pen and set aside the feed and nib. The nib is the point where the ink comes out and it is sometimes seamlessly attached to the feed, the part that holds and channels the ink into the nib.
Rinse out the feed and nib under running water to dislodge any excess ink. India ink is waterproof, so this will dislodge chunks but may not fully clean the pen.
Put the nib and feed in a solution of one part ammonia to four parts water for 15 minutes. If you have sensitive skin use rubber gloves to protect your hands.
Rinse the ammonia off under running water again, and gently rub the nib and feed to dislodge any remaining ink. If there is any ink remaining return it to the ammonia for another 15 minutes and rinse again.
Put the pen back together, reattach the India ink cartridge and test the pen. If it does not write after several tries, repeat steps 1-4 until the pen is completely clean.
If a pen is constantly clogging, try rinsing it with water after every use, as India ink often dries and clogs pens.
Make sure you work in a well ventilated space because ammonia can irritate the lungs if inhaled.