Holey carbon films mounted on standard EM grids are routinely used as specimen supports in electron cryo-microscopy, Adroplet of the sample containing, for example, a suspension of virus particles or protein molecules, is applied to the grid, blotted to a thin layer and rapidly frozen. The particles are then imaged where the liquid spans the holes, without interference from an underlying carbon support film. Many recipes for holey films have been presented in the literature, generaiiy employing some method of forming bubbles in a layer of solvent in which a material is dissolved that then forms a discontinuous layer as the solvent evaporates.