The Rotring company makes the famous Rapidograph technical pen that provided a simpler, less messy way to draw precise lines than with a ruling pen. Although computer-aided design has taken over most of the work done by Rotring pens, some draftsmen and artists still find uses for the Rapidograph, and still need to clean their Rotring pens.
Unscrew and remove the Rotring technical pen's cap. Unscrew and remove the barrel from the pen body and nib assembly. Unscrew and remove the colour-coded ink cartridge clamp ring from the pen body. Pull off the ink cartridge and rinse with clean water. Scrub the cartridge interior with a pipe cleaner if necessary.
Tap the back of the pen body on a paper towel to remove residual ink. Unscrew the nib from the pen body using the nib key. Flush the nib and pen body under a faucet of lukewarm water, or soak the parts in a cup of Rotring technical pen cleaning solution. The nib and pen body may also be flushed in a cup of cleaning solution using a large rubber bulb.
Shake off any remaining fluid and wipe all the parts dry with a paper towel. If desired, fill the ink cartridge with technical pen ink. Reassemble the pen and store it with the cap on and the tip facing up.
Rotring technical pens may also be cleaned by submersion in the chemical bath of an ultrasonic pen cleaner.