I wanted to ask about applying gel deodorant on Shabbat. The specific deodorant at hand is this one: http://oldspice.com/en/content/fresh-sweat-defense-soft-solid-antiperspirant
I’ve heard some say it’s soft enough to be applied, and others say the opposite. I’m not sure if it makes a difference, but I’m Sefaradi so maybe there are 2 psak halachot?
I have not seen the product, but it is marketed as a solid. This indicates it retains it’s form until smeared over the body, and is not a pourable substance. If this is the case it should not be used on Shabbos, as it may involve the Melacha of Memachek, smoothing out solid substances.
While the exact level of thickness may be unclear, it would seem one should be stringent as many spray deodorants are available.
The Maamar Mordechai (303:10) and Shut Zera Emes (Yoreh De’ah 89) address a similar issue issue and treat it as a Torah prohibition, and the Mishnah Berurah (303:81) writes similarly. Shut Yabia Omer (Vol. 4, Orach Chaim 28) writes that this is at least a rabbinic prohibition.
See also Shemiras Shabbos Chap. 14, nos. 48, 50.
See Igros Moshe O:C 1:112,113 with regards to liquid soap and toothpaste on Shabbos.