Gemara

29b - Mishnah: It is forbidden to cut hair or launder in the week in which Tish'ah b'Av falls.

Rav Nachman (and R. Elazar): It is forbidden to launder to wear, but one may launder and leave the clothing (for after Tish'ah b'Av);

Rav Sheshes: It is forbidden even to launder and leave.

Support (Rav Sheshes, for himself): The launderers of Rav's house are idle this week.

Question (Rav Hamnuna - Mishnah): On Thursday it is permitted (to launder) for Kavod Shabbos.

If this permits laundering to wear immediately, this does not honor Shabbos!

Rather, it permits laundering to leave (for after Tish'ah b'Av). This is permitted only on Thursday, but the rest of the week is forbidden!

Answer: Really, it permits laundering to wear immediately. The Mishnah discusses one who has only one garment;

Rav Asi: One who has only one garment may launder it on Chol ha'Mo'ed.

Question (Beraisa): It is forbidden to launder, even to leave for after Tish'ah b'Av. Our Gihutz (in Bavel) is like their laundering (in Eretz Yisrael);

We are not concerned for Gihutz of linen garments.

Rav Nachman and R. Elazar are refuted.

Rav: Laundering is forbidden during the week before Tish'ah b'Av. After Tish'ah b'Av is permitted;

Shmuel: Even after Tish'ah b'Av is forbidden.

Question (Beraisa): It is forbidden to launder in the week in which Tish'ah b'Av falls. On Thursday it is permitted for Kavod Shabbos:

If Tish'ah b'Av is on Sunday, the entire week is permitted;

If Tish'ah b'Av is between Monday and Thursday, before it is forbidden and after it is permitted;

If Tish'ah b'Av is on Friday, Thursday is permitted for Kavod Shabbos. If one did not launder on Thursday, he may launder on Erev Shabbos after Minchah.

Abaye or Rav Acha bar Yakov cursed those who ruled like this (to allow laundering on Tish'ah b'Av itself after Minchah).

Answer: Tana'im argue about this:

Beraisa - R. Meir: It is forbidden to launder from Rosh Chodesh Av until the fast;

R. Yehudah says, the entire month is forbidden;

R. Shimon ben Gamliel says, only that week is forbidden.

In another Beraisa the Tana'im argue similarly about how long one conducts like an Avel.

Question: All of them expound the same verse - "V'Hishbati Kol Mesosah Chagah Chodshah v'Shabatah". R. Meir learns from "Chagah" (Rosh Chodesh is called Mo'ed), R. Yehudah learns from "Chodshah", and R. Shimon ben Gamliel learns from "v'Shabatah".

Rava: The Halachah follows R. Shimon ben Gamliel.

Rava: The Halachah follows R. Meir.

Both of these rulings are to be lenient; both of them are necessary:

Had he said only that the Halachah follows R. Meir, one might have thought that even from Rosh Chodesh is forbidden;

Had he said only that the Halachah follows R. Shimon ben Gamliel, one might have thought that even after the fast is forbidden.

Rishonim

Rif: The Halachah follows Rav Sheshes, who forbids even to launder and leave.

Ran (DH Shabbos): When Tish'ah b'Av it is on Thursday, one may not launder that day for Kavod Shabbos. Abaye cursed those who launder after Minchah on Tish'ah b'Av when it is on Friday. All the more so one may not when Tish'ah b'Av is on Thursday (for it is possible to launder on Friday)!

Ran (DH v'Chivus): One may not even spread laundered sheets on the bed or use laundered hand towels or tablecloths in the week of Tish'ah b'Av. The launderers of Rav's house were totally idle this week.

Rif and Rosh (4:32): Rava ruled like R. Shimon ben Gamliel and like R. Meir to be lenient like both of them, not to begin from Rosh Chodesh and not to continue after the fast.

Rosh (4:32): The Halachah follows Rav Sheshes in Isurim. Also, the Mishnah supports him. According to Rav Nachman, it should forbid wearing laundered clothing, not laundering. It is unreasonable to say that he forbids wearing only clothing laundered during the week. Also, a Beraisa supports Rav Sheshes. The Yerushalmi says that when Tish'ah b'Av is on Shabbos, both weeks (before it) are permitted. Since the fast is postponed to the 10th, there is no week in which Tish'ah b'Av falls.

Rambam (Hilchos Ta'aniyos 5:6): In the week in which Tish'ah b'Av falls it is forbidden to launder and to wear Meguhatz clothing, even linen, until after the fast. Even to launder and leave is forbidden.

Lechem Mishneh: The Rosh asked, according to Rav Nachman the Mishnah should just forbid wearing laundered clothing. The Rambam answers this. It is forbidden to wear Meguhatz clothing during this week, but laundered clothing is permitted. Rav Sheshes agrees with this. This is unlike the Magid Mishnah, who says that the Rambam forbids wearing even laundered clothing.

Magid Mishnah: The Rambam omits the Heter to launder on Thursday for Kavod Shabbos because according to our calendar, Tish'ah b'Av is never on Friday.

Rebuttal (Lechem Mishneh): The Pirush ha'Mishnayos says that this Heter is according to R. Shimon ben Gamliel, who forbids even after Tish'ah b'Av. The Halachah is, after Tish'ah b'Av is permitted. No one permits before Tish'ah b'Av for Kavod Shabbos. However, the Gemara says that the Heter applies when Tish'ah b'Av is on Friday! Perhaps he explains that Abaye cursed for this, unlike Rashi who says that he cursed only for permitting on Friday.

Hagahos Maimoniyos (8): The Gemara permits on Thursday for Kavod Shabbos when Tish'ah b'Av is on Friday. All the more so it is permitted when Tish'ah b'Av is on Shabbos, for then the previous week is not the week of Tish'ah b'Av; we are merely stringent. Avi ha'Ezri says that it is the custom of all Yisrael to permit on Thursday for Kavod Shabbos.

Poskim

Shulchan Aruch (551:3): It is forbidden to launder in the week in which Tish'ah b'Av falls, even to leave the clothing for after Tish'ah b'Av. Even if he has only one cloak it is forbidden. What was laundered beforehand is forbidden to wear, spread on the bed or use for hand towels or tablecloths.

Beis Yosef (DH u'Mah she'Chosav v'Afilu): Rashi says that laundering for afterwards is forbidden because it looks like he diverts his mind (from mourning).

Rema: Our custom is to forbid all this from the beginning of Av until after the fast, if not for a Mitzvah.

Taz (4): The Maharshal says that our custom is to forbid from Rosh Chodesh everything forbidden in the week of Tish'ah b'Av, except for what pertains to Kavod Shabbos, such as a shirt and towels. It seems that the custom is to be stringent about sheets.

Mishnah Berurah (31): One may launder on Thursday for Kavod Shabbos if he does not have a (clean) cloak. Certainly it is permitted through a Nochri.

Rema: One may not give to a Nochri to launder after Rosh Chodesh, but one may give to a Nochri before Rosh Chodesh even if he will launder after Rosh Chodesh.

Mishnah Berurah (34): Poskim argue about whether or not one may give after Rosh Chodesh on condition to launder it after Tish'ah b'Av. One may be lenient regarding linen.