The rabbonon did not impose tumah on peshutei klei zechuchis as a heker that the tumah is only d'rabbonon. Where is the heker in tumah yeshona of metal keilim that the tumah is only d'rabbonon? Why isn't there a concern that people will burn terumah and Kodshim that comes in contact with a restored metal keli that is tamei with tumah yeshona?
Shmuel Leifer, New York, USA
Tosfos at the beginning of 15b (and at the end of 16a) maintains that one does burn Terumah and Kodshim that became Tamei through Tocho of glass vessels, since glass vessels are deemed similar to earthenware vessels, which are Metamei d'Oraisa through Toch. It is only when Terumah touches the outside of Klei Zechuchis, which is Metamei because we compare them to metal (to which they are not really similar), that we decline to burn the Terumah. In that case, there is no reason to assume that we do not to burn Terumah and Kodshim that touched Tum'ah Yeshanah of metal vessels.
This also appears to be the opinion of the Rambam, who cites the Halachah that we do not burn Terumah and Kodshim with regard to Peshutei K'lei Zechuchis (in Hilchos Kelim 1:5), but says nothing about not burning them when they touch Tum'ah Yeshanah of metal vessels (12:2). Indeed, the Gemara doesn't either.
It therefore seems to me that Chazal drew a distinction between K'lei Zechuchis, whose Tum'ah is purely mi'de'Rabbanan, and K'lei Matchos, whose basic Tum'ah is mi'd'Oraysa (see Tosfos DH 'Ela'). If so, it is possible that even Rashi, who claims that there are only six cases of Tum'ah de'Rabbanan that are burned, may concede that one does burn Terumah and Kodshim which came into contact with the Tum'ah Yeshanah of Klei Matchos, since that Tum'ah is an extension of Tum'ah d'Oraisa. (The list of six Tum'os is referring only to Tum'os which are purely of Rabbbinic origin.)
b'Virchas Kol Tuv,
Eliezer Chrysler.