Mishnah Negaim 11:1: All clothing can become impure from Negaim [diseased patches on skin, clothes, or houses that create impurity] except those of non-Jews. One who buys clothing from a non-Jew should examine it as if in the beginning [of the Nega]. Skins of sea creatures do not become impure from Negaim. If one attached them to [clothing made] from that which grows in the ground, even a thread or even a string or anything which can become impure, is is impure.

כָּל הַבְּגָדִים מִטַּמְּאִין בַּנְּגָעִים, חוּץ מִשֶּׁל נָכְרִים. הַלּוֹקֵחַ בְּגָדִים מִן הַנָּכְרִים, יֵרָאוּ בַתְּחִלָּה. וְעוֹרוֹת הַיָּם אֵינָן מִטַּמְּאִין בַּנְּגָעִים. חִבֵּר לָהֶם מִן הַגָּדֵל בָּאָרֶץ, אֲפִלּוּ חוּט, אֲפִלּוּ מְשִׁיחָה, דָּבָר שֶׁהוּא מְקַבֵּל טֻמְאָה, טָמֵא:

Mishnah Negaim 11:2: Wool from camels or wool from sheep which were mixed together: if most of it came from the camel, it does not become impure from Negaim, if most of it came from the sheep, it does become impure from Negaim. If it was half and half, it does become impure from Negaim. And so too with linen and hemp that were mixed together.

צֶמֶר גְּמַלִּים וְצֶמֶר רְחֵלִים שֶׁטְּרָפָן זֶה בָזֶה, אִם רֹב מִן הַגְּמַלִּים, אֵינָם מִטַּמְּאִין בַּנְּגָעִים. אִם רֹב מִן הָרְחֵלִים, מִטַּמְּאִים בַּנְּגָעִים. מֶחֱצָה לְמֶחֱצָה, מִטַּמְּאִין בַּנְּגָעִים. וְכֵן הַפִּשְׁתָּן וְהַקַּנְבּוֹס שֶׁטְּרָפָן זֶה בָזֶה: