The cool thing about Waterman’s ink is the fact you can tip the bottles on their side:
This makes getting the last of the ink from the bottle fairly easy. South Seas Blue (now “Inspired Blue” after the EU made them reformulate without phenol) is the only bottle I have on the go at the moment. It’s a really nice shade of turquoise that gets very exciting with a flex nib.
Even better, if you lay it on very thick you get a fantastic red sheen at the edges:
It’s pretty but not something I would write with often. And I found that it had flow issues in an Ahab.
Waterman inks are good, cheap and generally safe. Richard Binder recommends them for vintage pens (along with Diamine). If you like their limited range of colours they’re a safe bet. But that bottle design is just great, which is why I’m hanging on to my empties.