I have El Greco acrylic paints, purchased and opened some 1.5 years ago, of course, I open them only when I use them. But now I observe that water is not an efficient solvent for them any more. I don't manage to arrive at delicate, soft, liquid, flowing paint easily. Should I use some additives or some other solvent for my acrylics?
Of course, at the end I managed to liven up my paints but the flow is still not so smooth and liquid as expected.