Has anyone tried sealing the inside of a piston horn's valve casings with a sealant, such as Great Slide Slickcoat Sealant? Since the casings are brass like the inside of a bone's outer slide, it appears that it might work. My 6/4 size tuba could benefit from faster valves.

I tried it on my wifes Cornet and Tenor Horn with Hey Days. Seemed to work OK, hard to tell if it was a big improvement - probably not. Truth be told they worked well enough before but I can say it didnt have any detrimental effect - go for it!!