Is soldering 18k y gold to palladium the same as soldering 14ky
gold to palladium?
In a word, yes.
Now for the details…
Flux as per normal, use an 18K white easy solder (must be cadmium
free otherwise embrittelment can result). Don’t over polish (you can
undercut the solder seams), and try to pre finish the palladium part
as much as possible (less likely to polish away the gold part) as
palladium like platinum is much harder than gold.
An “almost” example:
yes it is using 14K, but the “rules” apply just as well to 18K.
Cheers, Thomas Janstrom.