Abstract: Thin multilayer signature control films having a large differential between the indices of refraction of adjoining layers are characterized by the use as the low index layer or layers of a material having a high coefficient of extinction and a very low index of refraction. The enhanced differential between the indices of refraction results in signature control materials which, in one embodiment, may be comprised of just a substrate and a coating and, in another embodiment, may be a supported or unsupported multilayer film comprised of as few as three layers that have performance characteristics equal to or exceeding prior art films comprised of 15-30 layers. Both continuous films and pigmented liquid coating compositions for signature control are provided. Improved pigments for liquid coating compositions are comprised of appropriately coated microspheres and microballoons.

Abstract: The invention relates to honeycomb core components having an undulating configuration reinforced with structural rods or columns which provide nesting sites for indexing with the flutes or nodes of adjacent components when assembled in stacked relation. Methods are also disclosed for producing the core components and assembling them in finished honeycomb core configuration.