Reference for Kelim 9:5

חֲרָסִין שֶׁנִּשְׁתַּמֵּשׁ בָּהֶן מַשְׁקִין טְמֵאִין וְנָפְלוּ לַאֲוִיר הַתַּנּוּר, הֻסַּק הַתַּנּוּר, טָמֵא, שֶׁסּוֹף מַשְׁקֶה לָצֵאת. וְכֵן בְּגֶפֶת חֲדָשָׁה, אֲבָל בִּישָׁנָה, טָהוֹר. וְאִם יָדוּעַ שֶׁיּוֹצֵא מֵהֶן מַשְׁקִין, אֲפִלּוּ לְאַחַר שָׁלֹשׁ שָׁנִים, נִטְמָא:

If potsherds that had been used for unclean liquids fell into the air-space of an oven, if the oven was heated, it becomes impure, for the liquid would eventually come out. And the same with regard to fresh olive pomace, but if it was old, the oven remains pure. If it was known that liquid comes out, even after three years, the oven becomes impure.

Jastrow

Jastrow