To ensure reliable ink flow, it is important to keep your calligraphy pen clean. Commercial reservoir pens may be stored with the cap on without drying out, but will need cleaning from time to time. Dip-pens should be cleaned after each use. The easiest way to do this is to simply rinse the pen in running water - cold or warm, never boiling. Allow to dry before storing. To remove dried ink, add a little ammonia to the water. Ammonia-based window cleaners are handy for stubborn deposits.