Polishing GoldPure gold is one of the most delicate metals in existence, which is why it is usually mixed with other metals (commonly nickel or zinc) to make it harder. When it comes to polishing gold, remember not to handle the metal more than you need to (it is preferable to wear cloth gloves), as the acid in your sweat can remove protective waxes in the polish you have just rubbed on and cause oxidization. For the polish, professional polishers use a gold-polishing compound made from ferric oxide and synthetic wax. If you wish to polish your gold at home, obtain this compound from a professional jeweler as some variants are far too abrasive for gold and could damage the piece. To polish, take a soft cloth, dab it with a little of the compound and buff. Once you have brought back the luster, finish with a coat of polishing wax.
Electric Weld CleanersFor the cleaning of industrial metals, such as brown oxidization marks on newly welded steel, an electric weld cleaner is often used. Using a mixture of electricity and phosphoric acid, the device restores the luster without disturbing the grain of the metal. To use, wrap a small fiberglass cloth around the wand to prevent drips. Then dip the wand of the cleaner into the phosphoric acid, switch the machine on and drag the electrified wand across the piece and the weld mark will disappear.
Steel and ChromeSteel and chrome usually require polishing because they have been used for motorbike or car parts and as such have acquired rust damage. Chrome is a hard metal, and if the rust has not corroded the metal to a significant degree, a professional can remove it with fine or super-fine steel wool, then polish with good-quality polish. If you're trying this at home, scrub the metal with the steel wool using plenty of water as lubricant. After the rust is removed, get rid of the small scratches caused by the steel wool with chrome polish and a soft woolen cloth.
For steel parts (such as your exhaust pipe) use a good-quality steel polish. To bring back the luster, motorcycle repair site Hawg Wash recommends dabbing the polish on a cloth and wrapping it around your exhaust, then quickly tugging the cloth back and forth until it shines.