[Avodah] Kashering with libun kal - some theory

[Arie Folger]

Rabbosai,

In the hope of clearing up some confusion, and at the risk of creating more 
confusion, I shall try to grapple with the difference of heteirah bala' and 
issura bala'. I dealt with these matters one and four years ago, but am 
writing from memory, I pray that lo ekashel bidevar halakhah.

We have all read on list how beli'ot heter can be purged with hag'alah, and 
hence also with libun kal. However, while this is based on a gemara (IIRC, a 
Mishnah, as explained by the gemara), why is that so? There is no indication 
in kelei Midyan that one should distinguish between beli'ot heter and beli'ot 
issur, nor is there any such indication from any of the other pessuqim 
dealing with beli'ot, in kelei qodashim.

Having perused the sources, I came to the conclusion, confirmed in a 
conversation with Rav J.D. Bleich, that mideOraita, we always need kol asher 
yavo baesh ta'aviru vaesh, etc. That, 'Hazal could and would NOT change.

However, as the gemara teaches, kelei Midyan were all benei yoman. Once 24h 
passed (or, according to a minority opinion, a night), mideOraita the vessels 
were permissible, and only by dint of rabbinic law were they subsequently 
prohibited. Heim amru veheim amru, and when they required kashering vessels 
that weren't benei yoman, they permitted kashering beli'ot hetter with 
hag'alah.

According to this logic, libun kal could only be performed after  24h. The 
most sensible heter IMHO for allowing libun kal without waiting 24 hours 
might be what R' "Celejar" (vie heist ihr?) suggested, that our ovens 
are 'hatzuvot (trivets) and otherwise only suffer from zei'ah, which can be 
dealt with through hag'alah.

RYM asked:
> While I suppose it's possible to argue that he's referring to libun
> hamur, what is the source or rationale for the idea that when doing
> libun kal, some hametz may reenter the utensil?

I see it differently. Libun kal doesn't sufficiently burn beli'ot to be 
sufficient on a deOraita level. Thus, only rabbinically considerable beli'ot 
can be removed that way. If one performed libun kal too early, the libun 
won't have any effect, for medeOraita it is worthless, and the time of heter 
for the deRabbanan didn't kick in yet.

Mo'adim lesim'hah,
-- 
Arie Folger
http://www.ariefolger.googlepages.com