Gemara

Beraisa: Peros (e.g. wine) of Shemitah may not be used for soaking (flax) or laundering;

R. Yosi permits this.

Question: What is Chachamim's reason?

Answer: It says "To eat" - not to soak or launder;

R. Yosi expounds "For you" - for all your needs.

Question: What do Chachamim learn from "For you"?

Answer: It includes other needs, but only those similar to eating, in which the benefit comes at the same time as Bi'ur (when the produce is used up);

This excludes soaking and laundering, for the wine is ruined immediately, and the benefit comes much later.

Question: How does R. Yosi expound "To eat"?

Answer (Beraisa): "To eat" - not for a bandage.

Suggestion: Perhaps we should rather exclude laundering!

Rejection: "For you" permits laundering.

Question: Why not learn the other way? Perhaps "To eat" forbids laundering, and "For you" permits a bandage!

Answer: It is more reasonable to permit laundering, which everyone needs, than a bandage, which not everyone needs.

Question: Like whom is the following Beraisa?

Beraisa: "To eat" - not for a bandage, Ziluf (sprinkling wine on the floor to scent the house), or to induce vomiting.

Answer: It is like R. Yosi. If it was like Chachamim, it would also exclude soaking and laundry.

Rishonim

Rambam (Hilchos Shemitah 5:10): Kedushas Shemitah takes effect on things used to launder such as Boris (an alkaline plant) and aloe. One may use them to launder, for it says "For you" - for all your needs. One may not use Peros Shemitah to launder or for a bandage. It says "For you to eat" - this excludes a bandage, Ziluf, inducing vomiting, soaking and laundering.

Kesef Mishneh: The Rambam rules like Chachamim. The Beraisa and verse ("L'Ochlah") connote that the argument is only about laundering with foods, but all agree that one may use soaps to launder, even though the Hana'ah is after Bi'ur.

Question (Kapos Temarim 40a DH Gemara): The Rambam (e.g. 5:21) holds that Kedushas Shemitah does not apply to wood. It should be like soaps!

Suggestion: Those texts of the Rambam that say that things used to launder do not get Kedushas Shemitah are correct.

Rejection #1 (Kapos Temarim, ibid.): The Yerushalmi explicitly says that they get Kedushas Shemitah! A Beraisa in the Bavli (Shabbos 50a) says that Boris and aloe have Kedushas Shemitah. It is difficult to say that it is like R. Yosi, who says that wood gets Kedushas Shemitah.

Rejection #2 (Aruch ha'Shulchan ha'Asid Zera'im 24:19): If they do not get Kedushas Shemitah, the Rambam would not need to expound why they may be used to launder!

Answer #1 (Kapos Temarim, ibid.): The Rambam holds that the benefit of things used to launder comes at the same time that they are used up (see Ri Korkus below).

Question: Chachamim expound "For you" to include other needs similar to eating, in which the benefit is at the time of Bi'ur. How can the Rambam use it to include laundering, in which the benefit comes later?

Answer #1 (Ri Korkus): The benefit of laundering is not wearing the laundered garment, rather, having a clean garment. When soaking laundry in wine, indeed, the benefit comes after the wine is spoiled. Regarding things used to launder, the benefit comes at the same time that they are used up. Rashi (Bava Kama 101b) explains similarly regarding dyes.

Answer #2 (to Questions (ii) and (vii) - Aruch ha'Shulchan, ibid. 21): The Yerushalmi expounds "for you" - for something everyone needs. This includes laundering; the Yerushalmi does not require benefit at the same time it is used up. The correct text of the Rambam say that things used to launder do not get Kedushas Shemitah, like the Bavli. He teaches that even according to the Yerushalmi, they may be used to launder because this is "for you".

Chazon Ish (Shevi'is 13:6): Rashi holds that it is permitted to use Peros Shemitah for dying, soaking and laundering only if vegetation usually used for these gets Kedushas Shemitah. R. Yosi permits these uses, and holds that such things and firewood get Kedushas Shemitah. Chachamim forbid these uses, and hold that such things do not get Kedushas Shemitah. The Yerushalmi says that they get Kedushas Shemitah, and does not say that it depends on this argument. According to Rashi, this is unlike the Bavli. The Rambam rules like Chachamim, but also like the Yerushalmi. He holds that Chachamim and R. Yosi argue about whether or not intent for produce for these uses uproots their normal status (of being to eat). R. Yosi holds that intent helps, and the produce gets limited Kedushas Shemitah, like dyes. Chachamim hold that intent it does not help, and they get full Kedushas Shemitah.