Re: over painting in watercolour linocut
Any water mixable oil paints/inks will dry waterproof, but the watercolour might not stick to those. The dried ink surface will remain bit oily that repels water and there is probably nothing where the watercolor could stick to. Many printmakers do color their prints using watercolors, but it is applied in the non-ink areas on the paper. That combination would work if you can design the artwork so that there is no need for watercolor on top of the ink.