Cerith Wyn Evans and Gillian Ayres: this week’s best exhibitions

From an ambitious commission by the Welsh artist to a timely retrospective of the veteran painter via west Africa and a Cornish beachNew works on paper by the globally renowned west African modern artist, who transforms junk into something beautiful. Salvage and recycling have become central to art in 21st-century Africa, and his ability to give new meaning to found objects has a lot in common with Robert Rauschenberg, Joseph Cornell and Kurt Schwitters. Yet the romanticism and passion for refle