Painting without acrylic medium….what’s that? Well, if you water down your acrylics too much the tension between the particles breaks down and the paint starts to separate, it creates nice effects but can result in the paint not sticking to the canvas/surface and flaking off somewhere down the line. That’s why they invented acrylic medium, you can thin the paint but it will still stick. The other way around this is to varnish the work afterwards.
But…in terms of environmetal sustainability I a not happy with acrylics and think I won’t buy any more after this batch is used up. Acrylics leave miniature plastice particles floating around the water system. Perhaps egg tempera is the solution? Especially as I am disappointed by the dullness of acrylics