Rapidograph and air bubbles
I've been at this for many years and have been satisfied with Rotring. (I tried multiple brands and this is the best.) However, recently I'm having far more than normal trouble with air bubbles that is forcing ink out and making it very difficult to work. I switched to a new head and still have the problem. I cleaned the other head and tried it again and nothing has changed. I even switched to a new cartridge. I open and pop the air bubbles and put take the head on and off a few times to release the air. Ink is still often coming out the tip. I'm using Dio Lanetzach (I don't want to use over the counter ink and I had been using Hadar 17 but it was very difficult to work with.) Could the ink be the issue? The bottle is a few years old and maybe something to the remaining ink in the bottle?