Today most signs are made from pressed sheet metal or twisted tubes filled with coloured neon gases. However, years ago, signs were made out of a metal core surrounded by a porcelain layer. The signs were then painted with text and images before being sealed with enamel. These old porcelain signs are growing in popularity as a collector's item. You can find porcelain signs at flea markets and antique stores. Unfortunately, because of their age, you may find that the sign you have purchased is damaged and needs to be restored. You could pay a professional to restore the porcelain sign or you could easily repair it yourself.
Use a mild soap and water to clean the dirt from the sign. Rinse away the soap and dry it with a clean, soft cloth.
Remove any rust that has formed where the internal metal plate is exposed. Wear rubber gloves. Wet the rust stain and use the pumice stone to rub the spot in a swirling motion. Pumice stones are volcanic rock that is traditionally used to slough off dead skin from your feet. Rinse the spot under running water to see if the spot is removed. If not, continue to rub the spot. Thoroughly dry the sign once the rust is gone. You can purchase pumice stones at beauty supply stores and at your local grocery store.
Touch up rusted spots. Add a layer of cold enamel to the spots according to package direction. Cold enamel is an adhesive that hardens, usually used in jewellery making and can be found at craft stores and hardware stores.
Polish the sign. Use an ammonia-based glass cleaner and paper towels to finish the restoration.
Leave dents alone. The only way to remove a dent is to hammer it out, which will cause more damage to the sign.
For extreme jobs, contact a professional. Do not over-restore the sign or you will lose the aged look. If there are just minor defects to the sign, it is probably best to leave the sign alone to avoid overworking the sign and detracting from the original work.