To cut a mirror without breaking it, prepare a clean, flat work surface covered with felt or cardboard. Measure and mark the cutting line on the mirror face using a grease pencil and straight edge. Apply a thin line of cutting oil along the intended path. Using a quality glass cutter, score the mirror surface with a single, continuous stroke applying firm, even pressure—you should hear a consistent scratching sound. Never go over the same line twice. Place a dowel rod directly under the score line and apply gentle, even pressure on both sides until the mirror snaps cleanly along the score. Immediately sand any sharp edges with fine-grit sandpaper. For curved cuts, make multiple straight scores following your curved line, then use running pliers to break away small sections gradually. Always wear protective eyewear and gloves, and practice on scrap mirror pieces before attempting valuable cuts.
