Repair a broken mirror using resin designed for filling cracks in windshields that is available at most auto parts stores, suggests eHow. Once the repair is complete, the crack becomes practically invisible, eliminating the need to throw away an otherwise serviceable mirror.
Clean the area surrounding the break in the glass. If debris is present inside the break, use the solvent to clean the area. Once the clean mirror dries, apply the stabilizer tape to the length of the crack. This tape has a peel-off backing that must be removed before application. Use your fingers to press bubbles that appear under the tape to the edge.
Fill the syringe included in the kit with the repair resin. Insert the syringe through the stabilizer tape and press the plunger to dispense the resin into the crack. Continue pressing the plunger until the material fills the entire length of the crack. Leave the tape in place while the resin cures. Refer to the kit directions to determine the curing time it requires.
Remove the stabilizer tape and apply more resin along the top of the repair. Immediately place the cure film from the kit over the resin. Once the second layer dries, remove the film. Use a razor knife to remove excess resin from the glass and clean the repair with glass cleaner.