Sounds like you’re a pro at restoration!
I’ve never had a rhodium plated piece in the shop for repair. If I
did, I’d remove the rhodium and/or nickel to get down to the base
alloy. Not doing so would be like soldering on top of firestain which
would produce a weak join.
Unfortunately, I’m not a big fan of Tix. It’s very brittle and the
flow quality is less than desirable. It’s akin to using a
cyanoacrylate - poor shear strength. Sorry Jo. So, when working with
white metal, I tend to go with plain ol’ tin/lead solder, drawing it
down to approx…020" and using short lengths as opposed to stick
soldering. If I do get a bit of solder on the plated piece I’m
working on, I’ll use a sharp burnisher (not a scraper) to remove it.
Or, I’ll gently heat that area and remove it with a Q-tip.
Then I’ll use Wright’s silver polish on a Q-tip and gently remove
any remaining residue. (Shhhhhhh, that’s a trade secret!). Since I
don’t do any plating, I make my customers aware that I will be doing
a STRUCTURAL REPAIR, and they may see a very thin solder line where
the white metal piece was reattached. There have been times that a
previous repair revealed the base metal, so after I re-repaired the
piece I’ll send the piece to my plater, should my customer desire.
The very rare occasions I will use tin/silver solder is if I
absolutely cannot identify if every last bit of lead solder had been
removed. It sometimes depends on the piece I’m working on. If I can
use my pulse arc welder, I go that route to maintain the integrity of
the object. For even if there’s lead hiding, the welding is so
localized that it won’t’ flow the lead. And Jo’s absolutely correct -
the high temperature when melting hard silver solder will of course
melt the lead, allowing it to eat into the silver like the Ebola
virus, creating its own alloy. I learned this lesson very early :~/
I hope this helps.