CLR is a commercial product available just about anywhere. Remember...delute it down 15 to 1. It is an acid that reacts with brass.
Glad you liked the lead pipe solution. However, becareful of pushing rods down the lead pipe as you do not want to scratch them. The swab on a nylon string easily wraps up and can be stored in a baggie in your trumpet case. It is so easy to use. Just take out your tuning slide, shake it to get spit out, take your mouthpiece off, drop the weighted swab and one second later...a clean lead pipe.