This specification covers expanded honeycomb core made of glass cloth impregnated with polyimide resin and supplied in the form of blocks, slices, and ordered shapes.This core has been used typically for bonded sandwich structures requiring high strength and corrosion resistance for long-term service up to 450 degrees F (232 degrees C) and short duration up to 700 degrees F (371 degrees C), but usage is not limited to such applications.