Abstract: A double-insulated glass window consists of at least two panes of glass held apart by plastic spacer members between the rims of the two panes. To prevent contamination of the space between the two panes by volatiles emitted by the plastic, the surface of the plastic spacer member, which is normally exposed to this space, is sealed by applying to it a very thin coating of foil or metal. To further improve the efficiency of the window this metallic surface is sloped at an angle so as to reflect radiant heat back toward the inside surface of the glass in order to help raise the temperature of the inside face of the glass pane.