Hand lotions are popular products, particularly during the winter when dry hands can benefit from moisturizing. Can they be applied on Shabbos? The answer is not as clear cut as some may think.
The presumed prohibition is memarei’ach, a sub-category of the Shabbos labor memachek. Memarei’ach means spreading. The Shulchan Arukh (Orach Chaim 316:11) rules that you may not rub your foot on spit on the ground on Shabbos because that smooths the dirt. The Magen Avraham (ad loc., 24) infers that you may rub the spit on a tiled floor. He asks why this is not a prohibited act of memarei’ach, since you are spreading the spit across the floor. His answer makes all the difference to our question.
The Magen Avraham explains that memarei’ach only applies when you intend to spread one item on top of another. Here, you want the spit to be absorbed by the floor rather than remain on top. Memarei’ach is a forbidden act of spreading a substance on top of another that that smooths it out, creates a smooth surface above it. Significantly, the Mishnah Berurah (ad loc., 49) rules according to this Magen Avraham.
Moisturizers come in both lotions and creams, the former being thinner and less viscous (link). Based on the above logic, R. Nachum Rabinovich (Si’ach Nachum, no. 20) rules that you are allowed to apply non-medicinal lotions on Shabbos. For his purposes, he determines that a handcream or vaseline (קרם ידיים או וזלין) is a lotion if it is a liquid that emerges from its tube with very little pressure, it immediately dissolves and is absorbed into the skin, and does not create a visible layer on the skin. Similarly, R. Shlomo Aviner (She’eilas Shlomo 3:123, 4:98) permits applying skin lotion on Shabbos if you make sure that it is completely absorbed into the skin.
However, R. Eliezer Melamed (Peninei Halakhah, Shabbos 6:5 – link) argues that users of hand lotion desire a thin layer on top of the skin that softens it. Therefore, he contends that it is dissimilar from the case of spit on a tiled floor and is forbidden.
In three responsa, R. Moshe Feinstein (Orach Chaim 1:112-114 – link) invokes the prohibition of memachek: toothpaste, liquid soap and lipstick. If we assume that R. Feinstein really meant memarei’ach, we can infer from the second case that he would probably prohibit hand lotion. Although, as R. Joseph B. Soloveitchik reportedly said (Nefesh Ha-Rav, pp. 168-169), R. Feinstein’s rationale is extremely difficult to understand.
R. Yehoshua Neuwirth (Shemiras Shabbos Ke-Hilkhasah ch. 23 n. 58) quotes R. Shlomo Zalman Auerbach as permitting hand lotion if it is fully absorbed. He also quotes some who said that the Chazon Ish leaned toward leniency on this. R. Neuwirth points to a contradictory ruling by the Chazon Ish and generally argues for stringency on this issue.
Setting aside the strict views of R. Feinstein and R. Neuwirth, I am at a loss to understand the debate. Is it whether hand lotion does, in fact, absorb completely into the skin? Or is it how much of a layer is necessary to be considered non-absorbed, a visible layer or just a desired layer of any depth?
(See the related post on toothpaste: link)