May one wash his hands with liquid soap on Shabbos?
Using liquid soaps on Shabbos touch upon the following three issues.
- The prohibition of Molid Davar Chadash [i.e. melting or dissolving].
- The Mimacheik/Mimareiach [i.e. smoothening] prohibition.
- The Molid Reiach prohibition [i.e. making a new smell].
The law by unscented liquid soaps:
Unscented liquid soap may be used on Shabbos. Doing so does not consist of a Molid prohibition or a Mimchaeik prohibition, or of any other prohibition. This includes even if the soap is slightly thick to the point that it cannot be poured like actual liquid but is rather more like a pasty substance. [However there is an opinion who is stringent against using liquid soap even when the soap is thin like water due to the smoothening prohibition. However, if one adds water to the soap, and it has thus already been dissolved with water, then it is permitted to be used according to all.] Practically, the custom is to avoid using thick liquid soap on Shabbos [and rather to mix it with water from before Shabbos]. [If one did not do so before Shabbos, he may nevertheless do so on Shabbos.]
Scented liquid soaps?
It is forbidden for one to wash his hands with scented water, as although the main intent is not for the scent but rather for the cleanliness, nevertheless one also intends in having his hands absorb the good scent and it is hencve forbidden to do so. [Accordingly, it is forbidden to wash ones hands with scented soaps, if one also intends that his hands absorb the good smell, and accordingly it is best to avoid washing hands with scented soaps on Shabbos as it is difficult to ascertain that one has no intent to absorb the good scent into his hands. However, if in truth one has no intent at all to create a good smell on his hands and is using it simply for cleanliness purposes, then it may be used. Furthermore, some Poskim rule that if one’s intent of using the scented soap is to remove a bad smell from his hands, then it is permitted to be used even if one intends to benefit from the good smell, being that its purpose is to get rid of the bad smell.
It is permitted to use liquid soap on Shabbos, although the custom is to liquify it with water before Shabbos, or to liquify on Shabbos before use if this was not done before Shabbos. Ideally, one should use only unscented soap to wash his hands, although if unscented soap is not available, then scented soap may be used so long as one does not intend at all to place the scent on his hands but simply to clean them.
 See regarding the prohibition of using a bar of soap: Admur 326:10; Rama 326:10; Tur; Iggur 486; Baal Hateruma 235
 See Admur 314:21; 327:1; 328:28; M”A 316:24, Levushei Serud on M”A; M”B 316:49; Ketzos Hashulchan 146 footnote 32
 See C!
 Ketzos Hashulchan 146 footnote 32; 138 footnote 31 regarding toothpaste; Aruch Hashulchan 326:11; SSH”K 14:16 footnote 49; Shabbos Kehalacha Volume 3 17:73
 The reason: As it is already a liquid and the bubbles that it creates have no significance. [ibid]
 Implication of Ketzos Hashulchan ibid; Shabbos Kehalacha ibid
 Igros Moshe 1:113
 So rules Az Nidbaru 1:16 brought in Piskeiy Teshuvos 326:8
 Shabbos Kehalacha Vol. 3 17:73
 The reason: As there is no prohibition of Molid in liquifying soap, as explained above regarding bubbles, and thus the entire remaining issue is Mimacheik, which is avoided once the soap is liquified. Furthermore, the Poskim rule that one may place even hard soap in a cup of water for it to make soap water on Shabbos, however one may not shake it. [See Ketzos Hashulchan 127 footnote 13; SSH”K 14:16 as explained above in Halacha 2 Q&A there, based on Ketzos Hashulchan 127 Footnote 2]
 Admur 511:7; Taz 511:8; Halachos Ketanos 1:19; Ben Ish Chaiy 2 Tetzaveh 11; Rav Poalim 2:51; Shoel Umeishiv Tinyana 2:7; Minchas Yitzchak 6:26 [see below in opinion of M”B]; Poskim in Kaf Hachaim 128:44 and 511:44 and so concludes the Kaf Hachaim ibid; Magen Avraham 511:11; 128:8 prohibits placing the secnt into the water, although he does not mention if this prohibition applies even if the scent was placed from before Shabbos.
Background: This ruling of Admur follows the ruling of the Taz which hold that the prohibition to create a new smell applies as well to skin. The Magen Avraham 511 [as well as Magen Avraham in 128:6]
Other Opinions: Some Poskim rule the prohibition of Molid Reiach does not to one’s skin being the smell does not last, and it is hence permitted to place perfume/cologne on the body on Shabbos. Thus, if one placed the perfume in the water from before Yom Tov it may be used. [Chacham Tzevi 92; Elya Raba 128:8; Ginas Veradim 3:16; Nechpah Bakesef 4; Shaareiy Teshuvah 511:4; Mishneh Berurah 128:23 and so is implied from 511:28; Beir Moshe 1:34 rules one may be lenient by skin, although one who is stringent is blessed; SSH”K 14:32 rules leniently that perfume may be applied anywhere on one’s body, as learns the Chacham Tzevi, as brought in M”B] These opinions can draw proof for their ruling from Michaber 327:1 and 328:36 in which the Michaber allows smearing rose oil on the body, and cheing scented gum in the mouth. Admur and the Poskim ibid however elarn that the scnted oil is permitted because one has no intent for the scent, while the gum is permitted because its intent is only to remove the bad smell.
According to the M”B may one add smells to other parts of one’s body other than the hands? In M”B 128:23 he rules that one may be lenient like the Chacham Tzevi and Elyah Raba that one may wash hands with perfume water. However the Minchas Yitzchak 6:26 explains that the M”B himself only allows this to be done to ones hands and not to the rest of one’s body, as perfume on ones hands rubs off quicker then on the rest of the body. To note however that the Minchas Yitzchak himself there leans to be stringent like Admur and the other Gedolei Haposkim which prohibit perfume on any part of the body. However Rav SZ”A [brought in SSH”K 14 footnote 92, and so they rule in Halacha 32] learns that the M”B permits applying perfume to any part of one’s body.
Placing perfume on ones hair: Is forbidden according to all opinions being that hair is considered like clothing to which all agree there is a prohibition of Molid Reiach. [Piskeiy Teshuvos 327:1, see Minchas Yitzchak ibid.]
 The reason: The reason for this is because they intend to create a new smell on the hands of the Kohanim. Now, although the scented oil is placed into the water from before Yom Tov, nevertheless [this is forbidden] being that on Yom Tov when the Kohanim rinse their hands they are creating a new smell on their hands, and they benefit from this smell, and it is pleasant for them and they intend to do so , therefore they are to refrain from doing so.
 See Shabbos Kehalacha Vol. 3 18:4 footnote 13 that it is very difficult to ascertain that one truly has no intent to absorb the smell.
 Shabbos Kehalacha ibid; See the following Poskim that it is permitted to do an action that causes a smell to enter into an item if one does not have any intention to do so: Admur 327:1; 511:7; Michaber 327:1; Mishneh Shabbos 111; Rashal Beitza 2:34; Taz 511:8; implication of M”A 511:10; Kuntrus Achron 511:1 based on proof from many Rishonim [Ramban; Ran; Rosh; Rif]; Neziros Shimshon; Mamar Mordechai; So rule regarding rose oil, that it may be smeared for pleasure purposes, thus proving that it does not contain a prohibition of creating a new smell if that is not one’s intent: Admur 327:1; Michaber 327:1; Mishneh Shabbos 111
The reason: As Holadas Reiach is a light prohibition and is hence permitted if one does not have intent to do so. [Machatzis Hashekel 658:2 in explanation of Rashal; Implication of Admur in Kuntrus Achron ibid] Others however explain the reason is because these Poskim rule one may be lenient by a Pesik Reishei of a Rabbinical prohibition, and especially if Lo Nicha Lei. [P”M 321 M”Z 7 and 511 M”Z 8; Chemed Moshe; Nehar Shalom; Shaar Hatziyon 658:6; as rules Terumos Hadeshen, brought in M”A 314:5; Shaar Hatziyon 316:21; See Beis Yosef brought in Taz 316:3; Admur 314:3 regarding bees] This however is incorrect as Admur rules stringently regarding Pesik Resihei Delo Nicha Lei even by a Rabbinical prohibition, as brought in 316:4 and 320:24]
 Beir Moshe 1:34 rules that good smells may always be applied in order to remove bad odors, and so rules Piskeiy Teshuvos [327:1, 328:26] Shabbos Kehalacha Vol. 3 18:6