This article examines the selective use of plant materials in design in Melanesia. It explores – through an analysis of pandanus leaf mats in New Ireland, Papua New Guinea – how makers select fibres on the basis of their capacity to express social relations to varying temporalities before their natural decay. J.J. Gibson's theory of affordance and Donald Norman's concept of mapping are critically applied for this purpose. This approach emphasizes how social and temporal relations are condensed into objects, and refocuses anthropological attention towards materials and their affordances in the production of material culture.