Mechanical strain is one of the most common tools used to tailor the properties of materials. In this sense, the ability to control chirality on demand, turning a right-handed structure into a left-handed one, is very desirable. The MPSD researchers have now shown that mechanical strain provides precisely such a handle. To demonstrate this effect, the team monitored the appearance of the crystal’s optical activity – a characteristic signature of chirality – while applying controlled mechanical strain. Tensile and compressive strain generate opposite handedness, while applying strain along different crystal directions provides another way to select the resulting chiral state.