There are many ink bottles in my drawer. Many I've reviewed many years ago and don't use often.
Recently, I opened the bottle of Daler Rowney Kandahar that I have and found out the ink pigment had settled and solidified into a huge block at the bottom.
I would usually put two stainless steel ball bearings into the bottle to help mix the ink. But this time the ball bearings are effective because the ink pigment block is too hard, and impossible to dissolve except with grinding it back down.
These are the smaller broken up ink pigment blocks from the larger block.
It's not surprising that the Kandahar ink is now diluted because it's mostly just binder left. The Daler Rowney Calli that I have still works fine. I can't remember when I bought that but the ink doesn't seem to have solidified despite not being used for a long time too.
Thankfully these inks are cheap so I'll probably throw away the one with the problem.
Let me know in the comments section if you have similar or different problems with your old inks and bottles, and what you did to make your ink work again.