Imagable precursors for masks and for electronic parts comprise a polymeric layer applied to a substrate. The layer comprises at least one polymer having infra-red absorbing groups carried as pendent groups on the polymer backbone. Certain infra-red absorbing groups may also act to insolubilize the polymer in a developer, until it is imagewise exposed to infra-red radiation. Imagewise application of heat, resulting from imagewise exposure of the precursor to infra-red radiation, renders the polymer layer more soluble in the developer than prior to exposure to the infra-red radiation.