Beautiful Vintage Conn 12A Coprion Professional Cornet - eBay (item 270278217415 end time Sep-27-08 15:29:51 PDT)
Photo #7 shows some suspicious areas on the bell bow of that Conn 12A.
I asked the seller if there is any red rot corrosion there on the bell bow or anywhere else on the cornet, and he said no.
But that area on the bell bow does not just look discolored.
It actually looks pitted.
But it is impossible to know if the pitting is from the inside (red rot) or from the outside (the Holton Super Collegiate I once owned had *extremely* minor exterior pitting in the copper in that same area of the bell bow).
Any expert opinions here about whether that is red rot?
I admit that the bell bow would be an unusual place for red rot to happen.