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1 Wash the glass backing plate in running tap water. Dry it with a clean paper towel and place it flat on another piece of clean paper towel on a clean, smooth, horizontal surface. This should be a table or a lab bench, which is at a comfortable working height for you. Wash your hands with soap and water and dry them with a towel. Seat yourselves (this is a team project) in chairs or lab stools around the table or bench.

2 Color the flat face of both mirrors with a permanent marker pen or colored grease pencil. The colored metal will show how much of the surface needs to be ground away. (When you have ground all of the color away, and the surface of the mirror is a uniform, dull gray, you will have properly removed the machine tool marks from the face of the mirror.) If you can't find a colored marker, that will be O.K. You can still judge your grinding progress by seeing if there are any shiny places left on the face of the mirror. Pick up the brown dropper bottle labeled "Aluminum Oxide Grinding Slurry." It contains a soupy, pink-colored mixture of very small particles of aluminum oxide powder suspended in water. When thoroughly mixed, this slurry is the consistency of cake batter, paint, or thick soup or cream. Shake the bottle vigorously for about a minute to mix

Using the dropper the water and aluminum oxide well. Squeeze the dropper bulb and release it to pull some grinding slurry up into the dropper. Unscrew the dropper, hold its tip over the center of the glass plate, and squeeze the bulb to release ten drops of slurry onto the plate. Put the dropper back into the bottle and tighten the cap. Pick up one of the mirrors (this will be your #1 Starshine Mirror) and set it face down into the middle of the slurry. Use the mirror to spread the slurry out evenly. Press down on the back of the mirror and grind its flat face against the
slurry on the plate, moving the mirror as though you were firmly writing the number "8" with it. Use enough downward pressure to feel the mirror drag on the glass. You will feel and even hear the grinding. Try not to tip or rock the mirror as you move it around in a "figure 8" motion, because that would round off the outside edge of the mirror and make it unusable. Don't hang onto the mirror stem; just press down on the back of the mirror with your fingers and let the stem act as a guide to keep your fingers in place while you Grinding the mirror
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