Army Painter Warpaints too thick.

[Mr. Peabody]

Opened one bottle and found something inside that looked like a coloured version of vallejo's Heavy Gel

Yeah, that's not "too thick", that's just broken. I'm with Obsidian3d, that paint has been stored incorrectly at some point in its life.

Maybe the Army Painter folks just didn't understand when you described the paint, quite rightly as too thick. They may not have a real customer service department or policy, just someone answering emails. 

[zizi666]

Sounds unusual really. I wonder if the place he bought them from stores them somewhere a little too hot? That's the only reason I can think of that they'd all be thick like that.

I've bought several single bottles, a small starter set plus their mega paint set and have never had any issues with the Army Painter stuff. I've stayed away from the Zombicide sets because I heard they were a lot thicker (and I don't need any more paint). If you find the water mixture affects the coverage too much, go with a higher ratio of matte medium.

I believe he ordered everything directly from Army Painter.
as for mixture, I already went for a 3:2 mix + a hint of flow release agent.
I have another unused dropper bottle so I could mix up a new batch with less water to try.