Detach the slide assembly from the bell. Now go find a sink with a plug. Fill the sink up with warm water.
Hold onto the inner slide brace with one hand and use your thumb to plug one of the holes. Dip the other hole under the water. Hold onto the outer slide brace with the other hand.
Quickly and forcefully work the outer slide up and down. You are using the suction power of the slide to force water up into the inner slide. You should see slide-cheese coming out into the sink.
Now switch holes: plug the other hole with your thumb and pull the water up into the inner slide opening.
Bonus Tip: Cleaning the Mouthpiece
Here's how to clean your mouthpiece if you don't have your mouthpiece brush with you! Get a piece of paper towel and rip it into thin strips. Roll a strip up length-wise, and work one end into the cup of the mouthpiece, down to where you can grab it coming out of the shank. Pull it through, and repeat several times with more paper towel strips. Wash the mouthpiece with hand soap and rinse thoroughly.
Related Web Sites
YouTube Video with Original Music
Cleaning Your Trombone
Online Trombone Journal
Keep it Clean: A Basic Guide to Trombone Care
Brad Howland is the Principal Trombonist of the Victoria Symphony Orchestra.