"At one time skim milk was used only by dieting females," reads the copy in an article from the 1951 issue of Mechanix Illustrated. "But now government research labs have found other uses for the casein fiber derived from it. See above: 1, 3 and 7, brushes; 2 and 6, straight fiber; 4, curled fiber used in carburetor air filters; 5. stiff cloth produced from bristle fiber." Brushes? Bristle fiber? Delicious! (Click image to see the full story.) [Modern Mechanix]