Why does the Torah keep on repeating the different kinds of garment on which the Nega appears (See Pesukim 49 & 51-53)?
Ramban, Seforno and Moshav Zekenim: To stress the fact that Tzara'as on garments is a miraculous phenomenon that has no natural explanation. 1
Which explains why Tzara'as Begadim is confined to white garments and only occurs in Eretz Yisrael (Ramban and Seforno). Refer also to 14:34:2:2* in connection with Tzara'as Batim.
What is "le'Chol asher Ye'aseh li'Melachah" coming to include?
What is the definition of "Tzara'as Mam'eres"?
Rashi #1 and Ramban #1: It means a painful Tzara'as. 1
Rashi #2 and Ramban #2: It hints 'Ten lo Me'erah' ('Curse it' - Do not derive any benefit from it). 2
Rashi #3 (in Yechezkel 25:24), Targum Onkelos 3 and Targum Yonasan: It means 'a lacking Tzara'as'. 4
Rashbam: It is a Lashon of curse and of lacking. 5
Moshav Zekenim and Hadar Zekenimm (in Pasuk 46): A Me'eirah (curse) was sent into it, which will spread to all of it, in which case it will have to be burned.
Similar to "Silon Mam'ir" ('a piercing thorn') in Yechezkel, 25:24 (Rashi - See also Ramban).
See Ramban, who elaborates.
The Ramban's text in Targum Onkelos is 'Segira Mechazra' (in place of 'Segira Mechasrsa), and he explains it like Rashi's first explanation (Refer to 13:51:2:1).
Which presumably, means that it detracts from the garment and destroys it.
Rashbam: As in Yechezkel, 28:24 and in Devarim, 28:20.