I drew this eagle sculpture at church yesterday, using my favorite Lamy Safari (dark lilac!) filled with an ink mixture I mixed myself. I know many ink artists out there advise against mixing inks but I've never run into problems doing so.
I originally bought the purple Lamy cartridges to go with this pen but they were a pinkish-purple -- too pink for my preferences. So I used a syringe to pull the purple ink out, mixing it with some brown samples I had decided against and a bit of black ink (all water-soluble). I ended up with this shadowy earthy purple-brown ink and love it!