I have two Lamy fountain pens. One I’ve been using for about eight years, with black ink, and one I got two or three years ago, with purple ink. Recently I realised that somewhere I had picked up a Lamy cartridge with blue ink. I suspect it was accidentally packed with black cartridges and I didn’t notice because I normally buy multiple packs at a time.

I decided to put it in the black pen and I wasn’t surprised that it didn’t immediately start flowing with blue ink. Because I normally stick with the same colours and I haven’t experienced blockages, I don’t normally clean the pens on each colour change. After a little while, the blue did start to appear although tinged black and then eventually more blue.

What surprised me though was that it hasn’t yet settled down two or three days later. I’m now sometimes getting blue and sometimes it drifts back to near black. To be honest, I’m quite enjoying the effect and, since it is only for personal note-taking, I am happy to keep watching it but it isn’t what I expected. I’m quite intrigued to see if I get similar vacillation when I put the next black cartridge in or whether the darker colour takes over more quickly. In addition, it will give me some idea of how many pages I can write between changes – another useful bit of information about my tools and materials.