Visitors to Tate Modern over the past few months will have been greeted by two massive ancient Andean-inspired quipu (knot) sculptures before shimmying off to immerse themselves in the Cezanne exhibition experience or to wander through the permanent collection.

The quipus, displayed at each end of the vast Turbine Hall of the old power station, represent poems in space, a metaphor for the union of all, that were burned and banned by the conquistadors. Yet their spirit lives on.

The two Hyundai Commission installations, ‘Dead Forest Quipu’, by Chilean artist Cecilia Vicuna are 27 metres high, are pale and ghostly and represent mourning for the destruction of forests, the impact of climate change and violence against the indigenous people. Made from found objects, unspun wool, plant fibres, rope and cardboard gathered by local Latin American communities along the banks of the Thames. With musical quipus resonating around the artworks, Vicuna is inviting people to create spaces for imagining and dreaming.

With artworks this delicate – Vicuna calls the assemblage of imperfect and modest items precarios (precarious) – and on such a large scale, how best to clean them? They are just about to come down at the end of their time in Tate Modern. LCN resident expert Roger Cawood says gentle vacuuming is probably one method. Any other suggestions? Answers on a postcard, please. Or maybe nowadays email is best. ­