Hello…glad you asked as maybe someone has an answer.

I use Gamblin relief inks a lot and for several colors I have they are very stiff. My Portland Intense Black, Pthalo Green, Hansa Yellow and Pthalo Blue are all very stiff. I do have tack reducer that I usually have to use with them.

The white has a nice flow to it and isn’t stiff what so ever. I really like it which is why I bought a lot of the other Gamblin colors. I’ve had major issues printing the yellow, but the others usually work out in the end.

It’s definitely not your batch. It might be normal. I usually mix the ink up with a putty knife and as it gets folded over on itself it usually starts to loosen up. I also use the tip of the knife to get as many of the lumps out of the ink as I can before printing. Once I do that with the black it usually goes pretty smooth from there.

I do think it may just be their ink.

I use a different ink but have similar issues. I find whites are fluid, blacks very stiff and the other colours somewhere in between. I’ve always assumed it was something to do with the chemical and physical properties of the pigments used.