Octopus Write and Draw Ink - Black Elephant Waterproof Ink for Writing, Drawing and Calligraphy - Non-fading, 50ml

Great ink, wish it was in bigger bottles as I go through it. Grey is subtle, but quite dark with layers, recommended.

Waterproof ink, nice brown colour would definitely recommend

I normally use this, and other such inks suitable for fountain pens, with watercolour. I've tried many such. This one is the best I've found for being waterproof, with no disturbance to the lines when watercolour is added. Almost all the others that are usable in fountain pens (I exclude dip pen shellack-type inks here), despite being advertised as waterproof, are far from being so, even after allowing much time for drying. (The only other ink I've used that comes close to it in this respect is the waterproof one manufactured by Sailor, which is also very commendable). In this regard, and in the fine flowing and enduring quality of the ink, I highly recommend this Octopus ink.

I've received a different colour (Grey Fox) than ordered (Elephant Grey), but that doesn't change the quality of the product and I'm going to keep it :). It is waterproof when completely dried, so I'm very pleased with that!

Good quality ink.Fully waterproof when dry. Refilled my fountain pen several times, and no issues with it getting clogged up with dry ink. I'm using it for sketching, and I chose a less black ink for a more subtle drawing effect. I use "Grey Meercat ", and it gives a nice grey/ black neutral tone.

This has become my go to ink for Drawing and line and wash. It flows well and when dry is very stable when putting a watercolour wash over a drawing. I use a Noodler fountain pen, which seems to suit it well.

Bought this ink to use in a Lamy refillable cartridge and can't fault it. Very smooth and lovely dark black ink and once dry, very waterproof

I got the Blue Koi some time ago, looking for some water-proof inks I could use at work. I had some pigment inks before but most often had issues with the flow and dry starts. So far this one performs with flying colours, but only really tried it in a handful of pens.It is a moderately saturated mid-blue with no undertones, and does present decent shading on fp-paper.