Crown Operations International, Ltd., and Mr. Marshall H. Krone (collectively “Crown”), appeal the decision of the United States District Court for the Western District of Wisconsin denying Crown declaratory relief that Solutia’s U.S. Patent No. 4,973,511 (“the ’511 patent”) is invalid for lack of novelty and non-obviousness, and that Solutia’s U.S. Patent No. 5,091,258 (“the ’258 patent”) is invalid for lack of enablement and written description. Crown Operations Int’l, Ltd. v. Solutia, Inc., No. 99-C-802-S, slip op. at 8 (W.D. Wis. Aug. 30, 2000) (memorandum decision and order granting summary judgment) (“August 30 Order”); Crown Operations Int’l, Ltd. v. Solutia, Inc., No. 99-C-802-S, slip op. at 24, 27 (W.D. Wis. Aug. 22, 2000) (same) (“August 22 Order”). Because we find no error in the district court’s opinion with respect to the ’511 patent, we affirm that portion of the district court’s decision. However, because the district court erred in its analysis of enablement for the ’258 patent, and did not address the written description issue for the ’258 patent, we vacate the district court’s grant of summary judgment on that issue and remand for additional proceedings consistent with this opinion.
I. BACKGROUND
The patents at issue in this appeal relate to layered films used to create safety and solar control glass. An example is an automobile windshield. Most windshields have two layers of glass with a multi-layer film between the glass layers. The multi-layer film adds properties to the glass assembly, such as impact resistance or providing a conductive layer that facilitates defrosting the windshield. An inner layer of the film has solar control properties to selectively reflect, absorb (and thus convert to heat) or transmit defined percentages of certain wavelengths of light. This inner layer is called the solar control film. It is made of a substrate coated by one or more layers of metal or metallic substances. ’511 patent, col. 3, l. 64 to col. 4, l. 2. Typically, manufacturers laminate the solar control film between layers of plasticized polyvinyl butyral (“PVB”) (sometimes called the “safety film”) in a process known as encapsulation. Then, the encapsulated solar control film is sandwiched between two pieces of glass for a final assembly of multi-layer glass with safety and solar control properties.
