Acrylic paint consists of pigment, water, and a man-made, soft plastic called polymer emulsion. The emulsion is a simple unpolymerized compound having a low molecular weight and when suspended in water stays intact as a liquid compound. Without a pigment, this milky-looking liquid plastic (known as polymer medium) will dry to a tough, flexible, and transparent film when brushed on a surface to allow the water to evaporate.
Most acrylic paints can be thinned with water or polymer medium and used as washes or glazes. Due to its rapid drying period and permeability, it is an excellent painting medium for abstract and non-objective paintings or decorative surfaces.