Yes, Charles Lewton-Brain is correct. One can solder after doing
keum boo. Although I usually complete my pieces before doing keum
boo, I had to repair a piece, which involved soldering it.
Figured I would make the repair, then re-keum boo. To my delight
I found that the subsequent heating and pickling in no way damaged
the keum boo. So, once again, Charles Lewton-Brain is correct. In
fact, if he says so, you can proceed with complete confidence.