Keilim2: 5
[ה] כִּסּוּי כַּדֵּי יַיִן וְכַדֵּי שֶׁמֶן, וְכִסּוּי חָבִיוֹת נְיָרוֹת — טְהוֹרִין, וְאִם הִתְקִינוֹ לְתַשְׁמִישׁ — טְמֵאִים. כִּסּוּי הַלְּפָס, בִּזְמַן שֶׁהוּא נָקוּב וְיֶשׁ לוֹ חִדּוּד — טָהוֹר; אִם אֵינוֹ נָקוּב וְאֵין לוֹ חִדּוּד — טָמֵא, מִפְּנֵי שֶׁהִיא מְסַנֶּנֶת לְתוֹכוֹ אֶת הַיָּרָק. רַבִּי אֱלִיעֶזֶר בַּר צָדוֹק אוֹמֵר: מִפְּנֵי שֶׁהִיא הוֹפֶכֶת עָלָיו אֶת הָרוּנְקִי.
[The] cover of wine jugs and of oil jugs and the cover of Neyarian barrels are tahor, but if it was prepared for [some] use, they are tamei. [The] cover of a stewpot — when it has a hole in it or it has a protrusion — it is tahor; if it does not have a hole or it has no protrusion, it is tamei, since she strains the vegetables into it. R’ Eliezer bar Tzadok says: Since she overturns the mass of cooked vegetables upon it.
Keilim2: 6
[ו] גִּסְטְרָא שֶׁנִּמְצֵאת בַּכִּבְשָׁן, עַד שֶׁלֹּא נִגְמְרָה מְלַאכְתָּהּ — טְהוֹרָה; מִשֶּׁנִּגְמְרָה מְלַאכְתָּהּ — טְמֵאָה. טִיטְרוֹס — רַבִּי אֱלִיעֶזֶר בַּר צָדוֹק מְטַהֵר; רַבִּי יוֹסֵי מְטַמֵּא, מִפְּנֵי שֶׁהוּא כְמוֹצִיא פְרוּטוֹת.
A gistera that was found in a kiln before its manufacture was complete is tahor; after its manufacture was complete, it is tamei. A titros: R’ Eliezer bar Tzadok rules [it] tahor; R’ Yose rules [it] tamei, since it lets out [liquid] drop by drop.