Before marching season begins:

Take your horn completely apart and clean it thoroughly. Make sure you have plenty of space to do this and it is very well lit. Many of us, including the author, know how easy it is to lose valve springs if you take your horn apart in an area that is poorly lit or if you do not have a place to put small parts. It is best to have a plastic bowl to keep all small parts like valves, valve springs and valve caps.

Place a towel in the bottom of your bath tub and lay the disassembled horn (minus the really small pieces) on it. The towel keeps any abrasives from scratching the finish of the horn.

Fill the tub with about 6 inches of lukewarm water. Next pour a couple tablespoons of dishwashing soap in the water and mix it up with your hands. The two best brands of soap for cleaning your horn are Palmolive or Joy. Other bands tend to leave a residue on the horn after it is rinsed. Put soapy water in the plastic bowl containing the smaller parts, but try to avoid getting the felt pads on top of the valves wet.

Let the horn soak for a few minutes to loosen any gunk, then use a valve casing brush to clean valve casings. The snake and the mouthpiece brush should be used to clean other parts of the horn.

Use a 100% cotton cloth to clean the exterior of the horn. Special cleaning cloths can be purchased from music stores for this purpose. If you do not have a cleaning cloth, an old, clean, plain T-shirt will work.

For smaller parts, like valve end caps, use cotton swabs to remove dirt, grease and foreign bodies. If you cannot remove dirt from end caps and old toothbrush can be used. You should avoid using toothbrushes on precision parts like piston valves and trombone slides as they may damage them.

Thoroughly rinse the horn and smaller parts to remove any soap residue.

Dry the horn with a soft cotton cloth.

Check with your director or local repair shop for any special instructions for bathing your horn. Some finishes require special care.

Spend a little time going over your horn when cleaning it. This will allow you the opportunity to find any problems that need to be addressed prior to the beginning of marching season. It is not uncommon for problems to develop with trombone slides, turning slides and water valves during the school year. If you thoroughly clean your horn prior to marching season, you should be able to identify the problems and get them fixed before the season begins.

Valve brasses should check felts, springs, etc. If there is a lot of noise or click once reassembled, new felts, springs or guides may be required. New springs or water keys or corks may be needed. Repair shops should be able to fix horns faster if they are clean!

Once the season begins:

Practicing outdoors exposes your horn to the elements. A horn will collect a lot of dust and dirt over the course of a season. This is especially true if you practice or perform in dusty or sandy conditions. Small particles of dust and sand readily stick to oiled parts like trombone slides and micro close tolerance piston valves. Add a drop or two of oil each day on every piston and slide. You should also plan on cleaning your horn at least once a month during marching season.

Also, clean the mouthpiece with a brush every couple days, and every day during band camp week. Long hours of playing cause them to get dirty, sweaty, etc., and keeping them clean keeps the horn cleaner longer as well.

Other tips:

Take care of your case. The purpose of your horn case is to protect your horn, but if your case is damaged, it may not be able to do its job properly. Cases are generally pretty durable, but I have seen people drop cases from high places and use them as battering rams, which can destroy them and their contents. Also, refrain from stuffing a lot of objects other than your horn in its case. The case your horn comes in was designed specifically for that type and model of horn. Putting a lot of extra items in the case with your horn could scratch the finish or worse. This is especially true for trombone players. All trombone players know that the slide is very easy to dent. Putting books or other rigid items in your case with your horn and then closing it can put pressure on your slide and cause it to bend.

Your horn is your best friend on the field. Without it you cannot perform your show. Protect and take care of it and it will perform well for you all season.