The is the permanent waterproof black ink that Platinum has formulated for use in fountain pens.
As the Platinum Carbon Ink suggest, it does use carbon particles in its ink. The ultra-fine carbon particles are what provides the permanence, waterproof and archival features of the ink.
As with all pigmented ink, regardless of whatever nano-particles or super-nano-whatever size particles, it's recommended to clean your pen once in a while and definitely do not let the ink dry in the feed.
I like the design of the glass bottle. Looks beautiful and it has a wide opening suitable for dip pens and brushes.
This scan has been adjusted for exposure while leaving the paper texture intact. Below are the close-ups.
It's an intensely black ink with excellent covering strength.
It's able to keep a sharp edge.
When dry, it's resistant to erasing, rubbing, smudge and water.
The ink flow is smooth, and it does not bleed over the next page.
One downside is it dries to a slight sheen at concentrated areas. This is something to note if you apply ink with brushes.
It can be use in fountain pens but be careful to clean your pens regularly since it's still pigmented.
For watercolour sketchers, it's a nice choice because the ink is waterproof and you can layer watercolour over it.
For writers, the ink is dark and doesn't bleed.
This is one of the more expensive ink I've used. It's usually selling around US $20 for a 60ml bottle. I suppose it's still alright if you're going to use the ink for long period of time. However, for comic inking, there are other more economic choices.
The other comparable ink to the Platinum Carbon Ink is the Sailor Kiwa-Guro Nano Ink.
Not sure why but on the Leda Art Supply sketchbook, Platinum Carbon Ink features but not the Sailor Kiwa Guro