When painters say acrylics, they mean acrylic paints: the bright, fast-drying colours that come in tubes or pots. The colour sits in a kind of plastic mixed with water, so you can thin them with water while you work, but when they dry they turn into a thin, tough skin that water will not wash off. Artists use the plural the same way they say oils or watercolours — not one tube, but the whole kind of paint. You hear it in art class and in the shop: a set of acrylics, work in acrylics. People also say acrylic paint; acrylics is the easy, painter’s-shop way to talk about them as a group. Though actually, acrylic by itself can also mean the clear hard plastic (a display stand, a phone case, a false nail), and in a salon acrylics often means those nails. In a studio, with brushes and water nearby, acrylics almost always means the paints.