Reference for Kelim 10:2
בַּמֶּה מַקִּיפִים. בְּסִיד וּבְגִפְּסִיס, בְּזֶפֶת וּבְשַׁעֲוָה, בְּטִיט וּבְצוֹאָה, בְּחֹמֶר וּבְחַרְסִית, וּבְכָל דָּבָר הַמִּתְמָרֵחַ. אֵין מַקִּיפִים לֹא בְּבַעַץ וְלֹא בְעוֹפֶרֶת, מִפְּנֵי שֶׁהוּא פָתִיל וְאֵינוֹ צָמִיד. אֵין מַקִּיפִין לֹא בִדְבֵלָה שְׁמֵנָה, וְלֹא בְּבָצֵק שֶׁנִּלּוֹשׁ בְּמֵי פֵרוֹת, שֶׁלֹּא יְבִיאֶנּוּ לִידֵי פְסוּל. וְאִם הִקִּיף, הִצִּיל:
How do they tightly fit the cover? With lime or gypsum, pitch or wax, mud or excrement, crude clay or potter's clay, or any substance that is used for plastering. One may not make a tightly fitting cover with tin or with lead because though it is a covering, it is not tightly fitting. One may not make a tightly fitting cover with swollen fig-cakes or with dough that was kneaded with fruit juice, since it might cause it to become unfit. If he did make a tightly fitting cover [from such material] it protects.