but how would you lower the pitch of a reed?
You file or sand metal off the lower third or so of the reed. That weakens the spring effect and slows the vibrations = lower pitch sound.
When one of you answer this one please add your thoughts on the use of solder/ untempering.
I try to avoid using solder on all but the lowest reeds, those which have weighted tips anyway. I have once or twice seen reeds more or less ruined by having solder applied to the lower third of the reed which in theory does raise the pitch, but also ruins the reeds response, making it sound dull and weak.
Untempering?
Tempering is the heat treatment process applied to steel after it has been hardened to reduce the hardness by a controlled amount to make it useful for its intended purpose. So if any thing soldering might temper it more, ie make it softer
Reed steel is tempered at temperatures higher than soft solder needs to melt, so using a good electric soldering iron you are unlikely to adversely affect the reed tongue.