I have been having some fun with the Masterpiece 60mm marker. I quickly exhausted the speedflow black ink it came with. This ink has the best effect through a new nib. I was unable to get this quality of streaking with any of the other inks. All of the following drawings are 18″x24″ in size.
Seriously though, look at these streaks:
Then I experimented with the purple One4All ink. Straight out of the bottle it is a little too thick to flow easily in this pen. I thinned with water and got some good effects although it became too fluid when the nib was fully saturated. My favorite effects were when the nib was still mostly dry.
I added black paint in an attempt to get a thicker effect.
Finally I used a bottle of india ink for fountain pens. This produced a good color and and flowed very well through the nib.