Sailor Kiraguro Nano Carbon Black Ink

I hesitate to use fountain pen ink at work for many reasons.  One of them is the watersolubility.  Things get spilt on them and then they become unreadable.  

On the other hand I have never bought a waterproof ink because knowledge of the ink's watersolubility is reassuring when I spill some, or stain my fingers or if the pen leaks. 

My explorations in watercolour have got me looking for waterproof inks, that I can watercolour wash over. 

The Australian pen and ink world rave about De Atramentis Document ink but I haven't been able to find it in any shops.

Noodlers bulletproof inks are also quite popular, but the shopkeeper told me there is currently a shortage of Noodlers inks. 

OK... Another ink I kept hearing about is Sailor Kiraguro Nano Carbon Black Ink.  I've always thought highly of
Japanese stationery and it's so easy to order online.  I bought a 50ml bottle.  You can get packaged of cartridges too.

It's supposed to not clog up fountain pens, hence the fountain-pen-friendly label.  It's a matte black black colour because it contains ultra fine particles of carbon. It's called a pigment ink, because the colour sits on the paper, which means it doesn't feather or bleed either.

I've used it for about a week now, in a cheap disposable Pilot fountain pen that I don't mind ruining.  I have heard that it can clog up pens if left too long unused.  It's been joyful to use and has become my daily pen. I can't believe I didn't buy it earlier. It glides on the paper I use at work, it's dark black, it photocopies well.  I haven't seen it smearing, but I'm not sure if that's because I'm careful when writing to blow on the paper or wait for it to dry before I touch it (this is a habit from experience). 

Another flash thing about the bottle is that there is a funnel within, so you can fill fountain pens from the bottle to the very last drop.  That doesn't do anything for me because I fill my pens with syringe and needle.