[Avodah] Rav Melamed on Metal Pots

[Eli Turkel via Avodah]

The article that discusses the experiment appeared in BDD vol 30 63-84
(Hebrew)
Experiments for comparing halakhic principles and empiric reality
regarding absorption and emission in utensils
by Yair Frank, Lavi Schiller and Rabbi Dr. Dror Fixler
earlier a halakhic discussion by them appeared inTechumim 34 113-129

They refer to several articles that discuss experimentation and halacha
by R. Nachum Rabinowitz and R. Ariel.
More specifically they refer to Pesachim 30b where Amemimar did an
experiment to check whether one can use certain vessels for Pesach. With
regard to glass Rashba also checked physically (shut Rashba 1:233)
The Radvaz was asked about porcelain and performed 2 experiments (shut
Radvaz 3:401) etc

The teshuva of R. Lior is found at http://www.yeshiva.org/ask/?id=71715
and http://www.yeshiva.org/ask/?id=56591

In terms of the experiment they did not test only for "taste" but also
for "absorption" . In particular, they weighted the vessel before and
after cooking food to see if it gained weight. This is the method used
by the Radvaz in his experiment. Today one can measure the diffusion of
molecules(or even atoms and ions) into the cooking vessel.

Since the general rule is that psak is not based on things that can only
be seen by a microscope they also check for specific molecules. Modern
taste research is based on 6 types of taste
    1) sweet
    2) salty
    3) sour (chamutz)
    4) bitter
    5) Ummami
    6) fat.
In the experiments they tested for types 1-3 as represented by specific
molecules and pH levels

They tested the following pots
    1) copper electrolytic
    2) Pleaze
    3) Steel 'with carbon
    4,5) 2 types of common noncorrosive steel
    6) aluminum
    7) pyrex
    8) glass
    9) clay (cheres)
the details of the pots are in the article. Most of the article details
the various experiments

Conclusions: the absorption in all the pots was extremely minimal except
for the clay pots.
using radiation the glass emitted much more than the metal pots. However
measuring a basic solution the metals and especially the steel emitted
more than the glass.

They suggest several future experiments including using pots from the
days of chazal and the rishonimIn. In particular R. Eitam Henkin (Hy"d) -
Hamayan 54:2 claimed that without comparing the results to ancient pots
the results are of limited value! The authors argue that we don't know
exactly what pots chazal used. They also didn't agree with the argument
that the sense of taste has changed from the days of Chazal.

The article concludes with an extensive table. One column is the change
is weight after cooking.
most were way less than 1%. while clay was about 9-10%

The more halakhic side was discussed in the Techumim article (deserves
a separate post)
While some poskim are willing to change the halakha based on modern
materials others like R Ariel and R. Asher Weiss disagree and insist on
the original halakha even for modern materials.

-- 
Eli Turkel