Rather than discard a mirror you've had for a long time, repair it. Repairing mirrors takes skill and patience, but it is a project worth the time. With a mirror resilvering kit, you can remove the damaged mirror backing and restore the mirror with a new reflective coating. Test your resilvering techniques on an inexpensive mirror before restoring the silvering on your valuable mirror. Give your old mirror a totally new appearance with a decorative frame as well.
Put on goggles and heavy-duty gloves during this project, and work in a well-ventilated area.
Dissolve the painted mirror back with paint remover. Apply a generous amount of the paint remover to the back of the mirror over the damaged area. Work it into the area, and wipe it away to remove the paint.
Apply the nitric acid solution in the resilvering kit to the mirror silvering on the back of the glass.
Gently scrape the glass with a glass scraper, but do not apply any pressure to the glass because it may crack.
Clean and wipe the glass surface with a lint-free cloth. This removes any remaining specs of debris from the glass that would interfere with resilvering.
Apply the new mirror silvering. Follow the instructions in the resilvering kit. Apply an even coat of the silver nitrate over the exposed glass surface.
Apply the protective backing to the mirror. Resilvering kits contain paints that seal and protect the silver. The first paint to be applied is the copper, and once that sets, coat the back of the mirror with the protective paint. Once it dries, you will have a restored mirror.
Remove the old frame of the mirror.
Measure the width and length of the old mirror. Use these measurements to cut the picture frame wood.
Mitre the frame wood with 45-degree-angled cuts. To overlap the edges of the mirror so that the frame supports it and it doesn't fall through, subtract one-half an inch from the width and one-half an inch from the length. This gives the frame a 1/4-inch overlap at each corner. Apply the measurements to the inner edge of the frame that meets the mirror.
Line up the mitred corners, apply wood glue at the joints, clamp them together and tap two tacks into each corner on the back side of the frame. The tack must overlap where the two pieces meet at the corners. Allow the frame time to dry over night.
Lay the mirror face down onto the back of the frame, and line it up at the corners. Screw the mirror brackets over each corner of the mirror, into the mirror frame.
Cut the craft paper to fit the back of the frame, and apply a thin bead of glue around the edges to secure it in place.
Screw on the picture-framing hardware. The weight of the mirror will determine whether the frame needs standard or heavy-duty picture-framing hardware. Line up the hardware at the top centre, or a few inches from each side if using two pieces, and screw them into the wood frame.
Do not put any stress on the mirror because it will break. Dispose of old silvering properly -- it may contain mercury.