YES, the Platinum Bars MUST be Enchanted by a lvl 34+ Enchanter. I found it
is best to just buy them for you as they only cost the Enchanter about
105pp, and a non-guild/friend Enchanter will only charge 10-15pp on top of
that for enchanting them. If you /hail Gavel, he will tell you who in the
Temple to give the enchanted platinum bars to in order to get the
appropriate piece in return (vulcanized, magnetized, etc). Although, please
note that the proper people do not respond to questions about the type of
platinum they give in return. You just have to trust (remember) what Gavel
says.