A transparent drying medium called Mont Marte Impasto is used to add texture and hold on to brushstrokes. Impasto can be directly blended with acrylics without affecting the final color's effect. Use water to clean up. Since it's water-based, you can't mix it with oils, but you can paint over it with oils once it dries. It gives paintings a more expressive quality and can even make paintings appear three-dimensional.