I purchased a hand held lemon squeezer which is meant to squeeze fresh lemon juice from a lemon into salad? I know that on Shabbos it is permitted to squeeze juice directly into salad. My question is if I can use this handheld nonelectric lemon squeezer to do so?
You should not use it on Shabbos even to squeeze lemon juice into your salad. It is only permitted to do so using one’s hands, being that using a specified vessel is a mundane act which defiles the sanctity of Shabbos.
Although there is no prohibition against squeezing juice into a salad for seasoning purposes, and according to some opinions there is no prohibition at all against squeezing lemons for juice, nonetheless, the Poskim of today and the previous generation write that one should not use a vessel that is designated for squeezing for this purpose. The reason for this is because we find precedent in the earlier Poskim to prohibit using designated vessels for even permitted activities such as the prohibition to use a grater to grate bread or cheese even though grating these products do not contain a grinding prohibition. Likewise, we find that one is not to use a designated Borer vessel for selection, and likewise is not to use a weekday brush for brushing hair, or use a weekday sponge for washing dishes, even if the brush and sponge are technically valid for Shabbos use. The reason for this restriction against using designated vessels is due to the fact that such vessels are usually used for a prohibited use, such as a grater which is used to grind foods that are forbidden to be ground on Shabbos, and a brush that is commonly used in a way that it pulls out hair. Accordingly, using such a vessel would be a belittlement of Shabbos as it appears like one is doing a mundane activity. Accordingly, the same should apply regarding a lemon squeezer, that since it can be used to squeeze fruits that are forbidden to be juiced on Shabbos, therefore using it even for permitted purpose, such as squeezing lemons into salad, would be viewed as a belittlement of Shabbos as a mundane act.
On the other hand, perhaps one can argue that a handheld lemon squeezer which is designated only for squeezing lemons should not have this prohibition of Uvdin Lechol being that its primary use is for squeezing lemons of which many Poskim rule that it does not contain any prohibition at all to be squeezed on Shabbos, and hence it ends up that according to these Poskim, this vessel is not at all designated during the week for an activity which is forbidden on Shabbos. Now, although we are practically stringent and avoid juicing lemons on Shabbos for the sake of drinking the juice, perhaps we do not need to go as far as to prohibit the designated vessel. Accordingly, it should be no different than a vegetable chopper vessel which contains large blades which the Poskim permitted to be used on Shabbos being that it is not designated for forbidden action during the week. However, in truth we can reject this notion being that a handheld lemon juicers can just as well be used for oranges and other citrus fruits, which does contain a prohibition to be juiced on Shabbos for the sake of drinking the juice, and hence once again we return to the issue of it being Uvdin Dechol. However, seemingly if it is designated only for lemons, and is apparent as so, then those who are lenient seemingly have upon what to rely, and hence we did not write above that it is straight out forbidden but rather that one simply should avoid it.
Sources: See Ketzos Hashulchan 126 footnote 19; Yalkut Yosef 320:8; Shabbos Kehalacha Vol. 2 p. 396; Piskeiy Teshuvos 320:1; See regarding the prohibition of using a grater on Shabbos due to the prohibition of Uvdin Dechol: Admur 321:8; Michaber 321:10; Rivash See regarding the debate if squeezing lemons for drinking their juice on Shabbos is forbidden: Forbidden: Yaavetz in Mor Uketzia 320; Tzemach Tzedek Shabbos 60 bring many arguments against this leniency of lemons, and thus sides to forbid it; M”B 320:9 and 22 in name of Chayeh Adam; Biur Halacha “Dino”; Kitzur SHU”A 80:12; Ketzos Hashulchan 126:11 footnote 25; Shabbos Kehalacha Vol. 2 p. 392 and 404; Permitted: Admur 320:10; Michaber 320:6; Teshuvas Rosh 22:2; Taz 320:5; M”A 320:8; Rosh ibid; M”B 320:22