This piece of fabric is from Fokker Dr. I 425/17, the Fokker Dr.I triplane which Manfred Von Richthofen crashed and died in on April 21st, 1918.  It is from the underside of one of the wings.  The fabric was initially covered in light-blue pigmented dope and then painted with a turquoise blue oil paint.  This oil paint was subsequently painted with vermilion red oil paint.  The light-blue pigmented dope is soluble in acetone whereas the turquoise blue and vermilion red oil paint are not.  The turquoise blue color you see are flakes of the vermilion red paint that have flipped over exposing the underlying coat.  Thread count is 54 threads per inch.  This piece measures 4-5/8 in. x 3-3/8 in. or 12 cm x 8.6 cm.  The second to last photo is a microscopic cross-section revealing the built-up layers.  This artifact is now on display in the Smithsonian Institution's National Air and Space Museum's new gallery, World War I: The Birth of Military Aviation in Washington, D.C., which opened on July 28, 2025; it's shown on display in the last slide.