While one may use liquid soap to wash one’s hands, the general practice is to be stringent about bar soap or thick liquid soap. There are two reasons for this. First, using bar soap or thick liquid soap resembles Memaĥek, since using a bar of soap smooths its surface and thick liquid soap is spread on the hands or body. Second, when one uses these kinds of soap it looks like he is producing something new, since the soap changes from solid to liquid. Although according to many poskim this use is not technically prohibited, because the person using the soap does not intend to smooth it and because the small amount of soap that is used is dissolved in the water, so it does not seem like anything new is being created, nevertheless, since there is some resemblance to Memare’aĥ and Molid, the common custom is to be stringent and avoid using bar soap or thick liquid soap. Those who are lenient have an opinion to rely upon.
If a thick liquid soap spreads out upon being left on a surface, it is considered liquid, and all would agree that one may use it on Shabbat. If it is uncertain whether a substance is considered thick or liquid, one may be lenient.
One may use wet wipes to clean a baby, to clean one’s body in general, or to clean a table and the like. Some are stringent because they maintain that there is a problem of Seĥita, since when using a wipe, one presses on it and squeezes out some moisture, which would help in cleaning. Nevertheless, the lenient opinion is the primary one, because the purpose of a wipe is to use the moisture on the surface of the wipe to clean more effectively. The purpose is not to squeeze out the moisture inside the wipe in order to wet the dirty area. If that were one’s goal, he would simply wash the area with water. As long as the wipe remains damp, he has no interest in the moisture that has not been squeezed out and separated from it, and thus no transgression has taken place. Even if, by chance, a couple of drops were squeezed out, since one did not intend for this to happen, he has not transgressed.
As we have seen (above 13:11), if one went to the bathroom and has no way to wipe himself other than to tear toilet paper, he may do so with a shinui such as using his elbows to pull the paper from the roll. This is because the Sages permitted transgressing a rabbinic prohibition to avoid great embarrassment. One may also, when necessary, wet toilet paper so it will clean more effectively, as long as one does not intend to squeeze out water from the toilet paper but only to make use of the moisture.
. MB 326:30 is stringent, based on Tiferet Yisrael, and maintains that one should not use this kind of soap because of Memare’aĥ. This is also the opinion of Ma’aseh Ish, p. 109, and R. Shmuel Laniado, Shulĥan Ha-melekh. Ben Ish Ĥai Year 2, Yitro 15 is stringent on account of Molid. However, several poskim are lenient, including Paĥad Yitzĥak, Ginat Veradim, and Pe’ulat Tzadik. Ketzot Ha-shulĥan agrees (138, Badei Ha-shulĥan 31). Yabi’a Omer 4:27 elaborates on this approach, adding that Rambam presents it in a responsum. R. Shlomo Zalman Auerbach, cited in SSK ch. 14 n. 49, states that technically one may use this kind of soap. Rather, it is an example of “things that are permitted but custom forbids,” and in such cases one should follow the custom. In practice, both SSK 14:18 and Or Le-Tziyon 2:35:5 forbid using it. R. Ovadia Yosef writes in Halikhot Olam vol. 4, p. 108, that it is proper to be stringent, and that this is the custom. However, it would seem that under pressing circumstances one may rely on those who are lenient, and even more so if one is uncertain whether his soap is considered thick or liquid. If there are cracks in bar soap and one wishes to smooth them out, this is prohibited according to all opinions.. Those who are stringent include Orĥot Shabbat 13:46 and Ĥut Shani vol. 2, p. 209. Minĥat Yitzĥak 10:25 and Shevet Ha-Levi 8:59 and 10:58 incline this way as well. Opposing them are Har Tzvi 1:190 and Va-ya’an Yosef OĤ §163, which rule leniently. Many others have also permitted this, including Igrot Moshe OĤ 2:70; SSK 14:37 and n. 99 based on R. Shlomo Zalman Auerbach; Rivevot Ephraim 6:194:3; Menuĥat Ahava vol. 2 ch. 12 n. 20; and Be-mar’eh Ha-bazak 3:48. See Harĥavot.