A simple cube is a brilliant way to understand some of the most important ingredients in realistic painting: light, shadow, reflected light and three-dimensional form. In this tutorial I’ll introduce you gently to masking fluid before we paint a lovely bright orange block. We’ll study how the light falls across each surface and explore the difference between the highlight, mid-tone, cast shadow and that subtle reflected light which bounces back into the underside of the shape. I’ll show you how to build the colour gradually, soften where needed and resist the temptation to keep fiddling once the paint begins to settle. It’s a wonderfully simple project, but there’s so much to learn from it. Once you start recognising these little shifts in light and tone, you’ll begin seeing them everywhere – and they’ll help you give all sorts of subjects much more depth and solidity.