While the overall look of older brass instruments makes very little difference to the quality of the sound they produce, these musical instruments can loose their luster due to regular handling and exposure to moisture. With their brass bodies and internal mechanisms, trumpets are particularly susceptible to tarnishing. In the majority of cases, old trumpets simply require a good cleaning of the internal mechanisms, polishing and an application of spray on lacquer to protect the metal and return the shine.
Fill a bathtub with warm water. After it has been filled, place a thick towel on the tub's bottom.
Disassemble the trumpet by pulling out the mouth piece, valves and slides. Put the valves in a safe place for later.
Place the slides into the water one at a time. Let them soak for one minute before cleaning them with the snake brush found in the trumpet cleaning kit. The snake brush is a coarse brush attached to a wire. Push the wire through the tubes inside the trumpet and draw the brush through slowly. Do this a few times, rinsing the tubes in the water after each time in order to remove any debris.
Submerge the main body of the trumpet in the water and leave it to soak for two to three minutes so that all of the tubes fill with water. Use the snake brush in the same manner as described in the last step to clean out the tubes. Use the casing brush on the valve holes. Insert the casing brush into the holes where the valves would go and rotate the brush to clean them. Rinse out the valves in order to remove debris.
Place the trumpet on a clean towel to dry naturally before reassembling. A little slide grease can be applied to both slides and valves after the trumpet has dried.
Polishing and Relacquering
Apply a teaspoon of acetone-based nail varnish remover to a cloth and rub it onto small areas of the trumpet to remove any remaining lacquer. You don't need to apply much pressure when applying the acetone. Keep in mind though that the acetone may need a minute to start dissolving the lacquer.
Rub a small amount of brass polish onto the metal in a circular motion using a lint free cloth. Focus on small areas with each application in order to ensure an even covering of polish.
Buff the instrument using a clean, lint free-cloth. Start by vigorously rubbing in a circular motion before finishing by applying less pressure in a linear motion.
Place the instrument on a piece of newspaper and spray a layer of lacquer over one side of the trumpet. Let the trumpet dry for two to three hours before applying a further three thin coats. Applying thin coats is important as it results in a finish free of air bubbles. The lacquer's drying time may vary according to the brand, so check instructions before use.
Turn the instrument over and repeat the lacquer application process so that the brass is completely relacquered.
Apply the spray lacquer in a well ventilated area and make sure all doors and windows are closed when it is drying. Air currents can cause dust to get caught on the wet lacquer.