Mishnayos Keilim Perek 25 Mishnah 6

The bases, rims, hangers or handles of vessels that have a receptacle upon which an unclean liquid fell, one dries them and they remain clean. But [if unclean liquid fell] on any part of any other vessel which cannot hold pomegranates (or in which no distinction is made between its outer and inner sides), the whole becomes unclean. If the outer side of a vessel contracted uncleanness from a liquid, only its outer side is unclean but its inner side, rim, hanger and handles remain clean. If its inner side contracted uncleanness the whole is unclean.

כַּנֵּי כֵלִים, וְאֹגְנֵיהֶם, וְאָזְנֵיהֶם, וִידוֹת הַכֵּלִים הַמְקַבְּלִים, שֶׁנָּפְלוּ עֲלֵיהֶן מַשְׁקִין, מְנַגְּבָן וְהֵם טְהוֹרִים. וּשְׁאָר כָּל הַכֵּלִים (שֶׁאֵינָם יְכוֹלִין לְקַבֵּל רִמּוֹנִים), שֶׁאֵין לָהֶם אֲחוֹרַיִם וָתוֹךְ, שֶׁנָּפְלוּ מַשְׁקִין עַל מִקְצָתוֹ, כֻּלּוֹ טָמֵא. כְּלִי שֶׁנִּטְמְאוּ אֲחוֹרָיו בְּמַשְׁקִין, אֲחוֹרָיו טְמֵאִים, תּוֹכוֹ וְאֹגְנוֹ וְאָזְנוֹ וְיָדָיו טְהוֹרִין. נִטְמָא תוֹכוֹ, כֻּלּוֹ טָמֵא: