Based on the above, we can perhaps explain a difficult Tosfos in Ta’anis (30a). Tosfos writes, that in a year when Tisha B’Av falls on Thursday, one is allowed to wash clothes on Tisha B’Av itself from midday and on, in honor of Shabbos. The Beis Yosef already asks, how can it be that one is allowed to wash clothes on Tisha B’Av itself? Moreover, asks the Beis Yosef, when Tisha B’Av falls on erev Shabbos, the Gemara (29b) says that if one didn’t manage to wash his clothes on Thursday he can wash them on erev Shabbos which is Tisha B’Av from Mincha time and onwards. The Gemara then brings, that Abaye would curse someone who did such a thing. The Beis Yosef asks, that if washing clothes on Friday is a problem, then certainly when Tisha B’Av falls on Thursday when there is still plenty time left until Shabbos, there should certainly be a problem?
If however, we explain that the heter to wash clothes on Thursday is because of takonas Ezra, in order to ensure that one is not too busy on erev Shabbos, then Tosfos is very understandable, and the reason Abaye cursed one who washes his clothes on erev Shabbos is because he is violating takonas Ezra as he should have washed his clothes on Thursday.
Based on the aforementioned Tosfos, the Bach (551:11) writes that if one is too busy on erev Shabbos to wash his clothes, he is allowed to wash his clothes on Wednesday (erev Tisha B’Av) even after midday in honor of Shabbos. Moreover he writes, if one is travelling during the week that Tisha B’Av falls out on, and he won’t be able to wash clothes in honor of Shabbos after Tisha B’Av, he can wash clothes in honor of Shabbos (even for a number of Shabbosos) during the week of Tisha B’Av. However, the Magen Avraham argues, and the Mishnah Berurah (551:39) says, that in such a case, one should give his clothes to a non-Jew to wash.
Based on all the above, there is certainly room to be lenient with washing clothes in honor of Shabbos, even on motzei Tisha B’Av itself. However, one should only wash clothes that are needed for Shabbos, clothes that are only needed for after Shabbos shouldn’t be washed until after midday on Friday (or ideally not until after Shabbos due to takonas Ezra). If however one washes them together with clothes that are needed for Shabbos, R’ Shlomah Zalman Auerbach is lenient (see Shalmay Mo’ed, Perek 93).
From the poskim it seems that the leniency of washing clothes, is only in regards to clothes that are being washed for Shabbos. Therefore, even on Friday morning before midday, one should refrain from washing clothes that are not needed for Shabbos, as in the end of the day, the minhogim [customs] of aveilus [mourning] are still in place. However, the Netei Gavriel (89:8) maintains, that since Chazal were lenient in regards to washing clothes for Shabbos, and according to all poskim one may wash clothes from Friday morning and on, Chazal no longer differentiated between washing clothes for Shabbos or for weekday, and they allowed all washing.
