How confused things get over time & when ink manufacturers misname their products ! It is quite staggering that this is no longer commonly known any more , not even HERE in the pen & ink forum !
India ink is lamp black suspended in shellac & it is totally water proof .
when dry - which takes leaving it overnight to be certain but it depends on climate & temperature.
It can be diluted with water to make washes of any strength , when dry they too are waterproof - an artist can use this to their advantage as many subtle washes may be laid down on top of each other creating effects of overlapping them & glazing where a very thin wash can "pull together" a few others underneath etc. etc. - experiment !
Often after a while you might notice that the ink gets too thick & sticky in the bottle & needs to thinned - you must use distilled water as the chemicals that a lot of water suppliers add can ruin the ink immediately !
(If you don't live in too polluted an area put a couple of dishes out to catch rain & fill an old bottle. That works fine too.)
NEVER put Indian ink into a fountain pen - it will dry inside & kill it.
Only ever use a dip pen or brush but keep rinsing out in a glass of water after every few dips as it can ruin a nib or brush if it starts to dry.
It all sounds a bit of a hassle really doesn't it?
Well you'll see why many people persist with this traditional medium if you closely examine a drawing done with it - a slightly raised line sits on top of the page , you can feel it with a finger nail !
It is as BLACK as could be & totally waterproof.
It will outlast anything labeled as "permanent"
Used with Bristol board there is no better looking ink nor one that can achieve such sharp & fine lines.
There are different manufacturers & Indian inks do vary in quality.
The best is widely acknowledged to be "Winsor & Newton" Indian ink.
I personally like "Senellier" Encre de Chine " (Encre de Chine is the European term for Indian ink).
There are many very good ones & a few awful ones ! , worse of all there are manufacturers who include " india or indian ink in the title & they are not at all
-basically it must have shellac
in it for it to be Indian ink .