What's That Fiber?

Day 154: Today, we're going to play a little game called "What's That Fiber?" I was curious as to whether my fingers could distinguish the bamboo/rayon in a mixed roving, so I put some samples under the microscope. There are two cellulose fibers here (as in "plant-based") and wool from two different breeds of sheep (Coopworth and Merino). Cellulose fibers are made by pulping plant material and treating it with chemicals to break it down into a solution which can be extruded, and therefore they tend to be smooth. On the other hand, wool is a protein-based fiber with a rough cortex (outer layer). As opposed to other sources such as rabbit or camel, sheep's wool varies in diameter from breed to breed. Merino is classified as a fine wool, rated at 15-25 microns; Coopworth comes in at 30-39. By comparison, an average human hair measures 70 microns. Cotton fibers average from 11-22 microns, rayon for fabric production falls between 8-25. Given this information, you should be able to identify the bamboo, cotton, Merino and Coopworth fibers shown above. In the top and bottom rows, magnifications are 40x, 200x and 800x. The second row shows a "mixed" fiber at 40x and 200x, with the two fibers isolated in the third row at 800x. Are you ready? Go! (Answers below.)

(Top row: cotton; Second row, mixed; Third row, bamboo and Merino; Bottom row, Coopworth)