Using Bar and Liquid Soap on Shabbos
Question: Why is it prohibited to use bar soap on Shabbos?
Discussion: While it is generally accepted in the Ashkenazi community53 that bar soap is not used on Shabbos, the exact reason for this is unclear. The poskim suggest several possibilities as to how this custom evolved:
- Certain types of bar soap were so abrasive that they uprooted hair, possibly transgressing the Shabbos Labor of Shearing.54 This reason would no longer apply to soaps nowadays.
- Some poskim55 compare using bar soap to crushing ice or snow into water, which is prohibited because of molid, transforming a solid into liquid. Similarly, when one washes with a bar of soap, a solid substance is changed into a creamy liquid. Other poskim, however, reject this comparison and maintain that using bar soap is not a violation of molid. 56
- In the past, bar soap was not a solid, rigid bar like it is today, but rather soft and pliable with a wax-like consistency. Using it entailed smoothing and evening it out, thus possibly transgressing the Shabbos Labor of Memachek, Scraping.57 Some poskim feel that this remains a problem even with some modern-day soaps, since the edges of the bar get rounded off and evened out when used. This is especially true when a started bar of soap has been left standing partially submerged in water, causing the bottom of the bar to become extremely soft and uneven. When this bar is used next, one inevitably will smooth the uneven surface of the partially “melted” bar.
Although all the reasons stated above are debatable and may or may not be applicable to modern-day bar soaps, it is still accepted that bar soap is not to be used on Shabbos. This longstanding minhag Yisrael remains inviolate.58 Bar soap, therefore, is muktzeh.
Question: Does the custom which prohibits using bar soap apply to liquid soap as well?
Discussion: No, it does not. The majority of poskim59 permit the use of liquid soap on Shabbos and the prevalent custom follows their view.60 Since none of the concerns mentioned earlier regarding bar soap apply to liquid soap, no custom was ever established to prohibit its usage.
A dissenting opinion is found in Igros Moshe.61 Rav Feinstein debates whether Smearing applies to liquid soap as well, since we can see that liquid soap becomes runnier and more “smooth” during the washing process. While he does not render a final ruling on this issue, he recommends that one be stringent, and he instructed the members of his household to be stringent in this matter.62 In deference to Rav Feinstein’s ruling, some people dilute their liquid soap (before Shabbos) so that it is considerably watered down.63 But, as stated earlier, the prevalent custom follows the opinion of the poskim who permit using liquid soap without first diluting it.
But some poskim maintain that not all liquid soaps are created equal. There are some liquid soaps that have a high viscosity level and pour out very slowly. These liquid soaps are more like thick oils and creamy lotions which are subject to the prohibition of Smoothing, and they may not be used on Shabbos64. Short of using a viscometer, anyone can estimate the viscosity level of a particular liquid soap by pouring some out onto a level surface. If the liquid spreads immediately, as water would, then its viscosity level is low and it may be used. If, however, it begins to pool and does not spread right out, chances are that its viscosity level is high and one should not use this product on Shabbos.65
53. See Yechaveh Da’as 2:50 and Ohr L’tziyon 2:35-5 regarding the custom of the Sefaradim.
54. Rashi, Shabbos 50a, s.v. lo, and Ran, ibid.
55. Rema O.C. 326:10
56. Mishnah Berurah 326:30.
57. Tiferes Yisrael, quoted by Mishnah Berurah 326:30.
58. Ketzos ha-Shulchan 146:32; Rav S.Z. Auerbach (Shemiras Shabbos K’hilchasah 14, note 49). See earlier note concerning the custom of the Sefaradim.
59. Aruch ha-Shulchan 326:11; Kaf ha-Chayim 326:43; Rav Y.S. Elyashiv (Koveitz Teshuvos 1:38).
60. Kitzur Hilchos Shabbos 32:4.
61. O.C. 1:113. See also Chut Shani 14:2.
62. In a personal conversation, Rav Feinstein stressed that he is aware that his opinion is a minority opinion and that it differs from that of the other poskim who discuss this matter.
63. Az Nidberu 10:16.
64. See Chut Shani 14:2. Rav Elyashiv, however is quoted is permitting all types of liquid soap, regardless of their viscosity level; see Ashrei ha-Ish, Shabbos 29:6.
65. According to the Star-K, who used a viscometer in their testing, Softsoap Liquid Hand Soap and Softsoap Anti-Bacterial Liquid Hand Soap with Light Moisturizers, for instance, have a high viscosity level and may not be used on Shabbos, while Ultra Dawn Concentrated Dish Liquid/Anti-Bacterial Hand Soap, as well as most regular liquid dishwashing soaps, have a low viscosity level and are permitted to be used on Shabbos. (Kashrus Kurrents, vol. 24, no. 2)