In the Efectos Cruzados (2020) series, Monterroso uses a blue Mayan plant dye, indigofera guatemalensis. This dye is made by combining a clay mineral, palygorskite, with the pigment from the native Central and South American indigo plant, indigofera suffructiosa. Since 300AD, Mayans have used the dye to decorate their bodies as part of the ritual to Chaac, the rain deity. Monterroso uses traditional techniques to make her own dye; fermenting the indigo plant and extracting the distilled pigment from its leaves. The indigofera suffructiosa plant was also cultivated and exported by Spanish colonists. Deemed to be sacred because of its colour, the dye became a valuable commodity that played a role in the transatlantic trade routes that violently shaped the 16th century global landscape. For Efectos Cruzados, she contorts strands of thread around two wooden paddles, before submerging them into a pot of hot water mixed with indigo dye.