I had used this method for many years, within 1-5 minutes in proper solution distilled water and a few drops of liquid detergent soap works well. For the most stubborn of stubborn a pre-soak overnight in a soapy solution is a good prep for the ultrasonic.
Read these articles for more information. Hmm, this link appears rather long. Otherwise, just Google.... how to use ultrasonic cleaner for fountain pens.
on April 20, 2026, 10:01 pm, in reply to "