Why is Yad Soledes Bo so Cold?

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  • #1765773

    Neville ChaimBerlin
    Participant

    The temperature generally described as yad soledes bo (110 degrees) is not actually that hot. It’s less than 20 degree hotter than human body temperature, which implies that it would not actually cause you to jerk your hand back. The water temp at which we bathe and shower is almost certainly higher than this or at least close.

    Why did the poskim set it so low? Did they shave a bunch of degrees off of true yad soledes bo to avoid accidental transgressions? And, why are there articles on kashrus sites that say there’s not a concern of sink water being too hot (eg. when one uses one sink for meat and dairy) when sinks easily go over 110?

    #1765839

    It’s less than 20 degree hotter than human body temperature, which implies that it would not actually cause you to jerk your hand back.
    Others describe it as the temperature a baby’s stomach will scald. Have you boiled water to 110 degrees (tested it with a food thermometer) and actually put your hand in?

    First it is the shita of R’ Moshe Feinstein TZATZAL that we have to be machmir that 43 degrees Celsius (approx 110 degrees F) as stated in (IGROS MOSHE ORACH CHAYIM (4:74) UNDER bISHUL NOTE GIMMEL) “HU KVAR CHOM GADOL SHEYESH LACHUSH LYAD SOLEDES KEFI MAH SHEHBDAKNU BATZMEINU. VEHASAFEIK YESH LACHUSH AHD 71 MAALOS CELSIUS (APPROX 160 DEGREES F) HU VADAI YAD SOLEDES.”

    http://hebrewbooks.org/pdfpager.aspx?req=920&st=&pgnum=137

    I am pretty sure that R’ Shlomo Zalman held it was 45 degrees Celsius (113 degrees F).

    #1765955

    rational
    Participant

    Indeed, Rw Shlomo Zalman zt”l held that it was 45 degrees Celsius.

    Machon Tzomet manufactures their Shabbat devices with this psak in mind, and because of the nature of thermostats, allows for a small error. Therefore, they set their products at a maximum of 40 degrees Celsius (104 degrees F).

    I’ll add that the halachah does not say אצבע סולדת בות but rather יד סולדת בו , indicating that any part of the hand that would recoil is considered too hot. Essentially, this criteria determines an upper limit. Once the hand recoils, it’s already too hot, so it’s best to be cautious and set the temperature less than the limit.

    One more thing. One cannot compare air temperature to being immersed in water. A human can survive very hot or very cold air temperatures, but not water. At a water temperature of 50-60 degree F, one can lose consciousness within a few hours. On the warmer side of the scale, cells start to die at a water temperature of 106 F.

    #1765951

    Avi K
    Participant

    Rav Shlomo Zalman Auerbach determined 45 degrees Celsius. He reasoned that if the blood does not prohibit the knife it must not be yad soledet. The kosher creature with the highest body temperature is a bird whose body temperature is slightly lower.

    #1766042

    Neville ChaimBerlin
    Participant

    “Have you boiled water to 110 degrees”
    No, and neither has anyone else. It’s physically impossible to boil water at 110 degrees F. It boils at 100 Celsius.

    “110 degrees (tested it with a food thermometer) and actually put your hand in?”
    I looked up average shower temperature and got 105, which makes sense because it’s going to be higher than human body temperature. I highly doubt an extra 5 degrees to the average would make it unbearable.

    Either way, the Reb Moshe you brought seems to answer the question.

    #1766094

    Neville, you are correct I was not precise in my terminology. I should have said heated up to 110 degrees. Rabbi Ribiat in his sefer the 39 melochos (Vol 2 page 58) agrees with you that bath water is around 104-105 degrees and is comfortable for some adults.

    #1766131

    interjection
    Participant

    110 degrees is starting to sting.

    5 minutes can make a huge difference. Just think about the difference in weather between 88F and 93F. In 88 you’re hot but it’s tolerable. 93 is already starting to be suffocating.

    #1766150

    ubiquitin
    Participant

    NC

    I once asked your question to R’ Belsky z”l (I am almost certain it was R’ Belsky this was years ago, it may have been R’ Heineman yibadel lechaim). He said that yad Soledes bo isn’t judged when you are bracing yourself for hot water, people can touch and not recoil and far hotter water than 110 degrees, when they expect it. He said that yad soledes bo is judged when you don’t expect it, imagine using your negel vasser and finding it 100 degrees, you’d be surprised but not recoil your hand at 110 degrees if you weren’t expecting it you would pull your hand back, though you could will yourself to keep your hand in place.

    I asked him where he got this distinction from, and he said its obvious, and that if it ws the same temperature, as that f scalding baby’s belly this had to be peshat

    #1766154

    Neville ChaimBerlin
    Participant

    “I asked him where he got this distinction from, and he said its obvious, and that if it ws the same temperature, as that f scalding baby’s belly this had to be peshat”

    If you’re already operating under the assumption that it’s 110 degrees, then yes I could understand why someone would say that this understanding is “obvious,” because it’s almost the only way that it makes sense. However, if one were just learning it raw, I don’t see how that’s so pashut.

    I’m not an expert on the lashon, and we’re talking in translation here, but is it definitely so pashut that “scalding a babies belly” would require a lower temperature than causing an adult hand to retract?

    #1766205

    Quayboardwarrior
    Participant

    “It’s physically impossible to boil water at 110 degrees F. It boils at 100 Celsius”
    -Neville ChiamBerlin

    Actually, the boiling point of water is dependent on atmospheric pressure. The lower the atmospheric pressure, the lower the waters boiling point.

    For example, higher altitudes. At 2400m, water boils at 92c.

    In a vacuum chamber, it would absolutely be “physically” possible to boil water at 110.

    #1767622

    Redleg
    Participant

    Different poskim have different values for yad soledes bo (YSB). I have seen values from as low as 110 degrees F to as high as 160 degrees. Current practice is to use both values l’chumrah. As a side note, I wonder how some poskim came up with their published values for YSB. Clearly, in the times of the Gemora, there was no way to objectively determine objective values for temperatures lower than boiling water. I have always understood that YSB was a temperature which was not simply uncomfortably hot but a temperature at which one’s hand would reflexively recoil. To my mind, the commonly accepted lower limit of 110 does not come close to meeting the the description.

    #1767638

    Neville ChaimBerlin
    Participant

    “I have always understood that YSB was a temperature which was not simply uncomfortably hot but a temperature at which one’s hand would reflexively recoil. To my mind, the commonly accepted lower limit of 110 does not come close to meeting the the description.”

    That’s essentially exactly what I was saying in the original post. See Ubiquitin’s comment about what R. Belsky said on this, which helps a little bit. Also, in the Reb Moshe mentioned above he calls 160 “vadai yad soledes bo,” which probably implies that’s the actual temperature where a normal, adult hand would recoil. 110 might be for an extremely sensitive hand (or an unsuspecting hand as in R. Belsky’s shittah) that we’re choshesh for.

    Would there be kashrus ramifications where we could rely on 160 if they’re d’rabbonon? (Not asking as a serious shailah, so don’t say “ask your LOR”)

    #1767734

    Reb Eliezer
    Participant

    It is not the hand but the belly of a baby כריסו של תינוק רופס.

    #1767776

    Reb Eliezer
    Participant

    I used above the wrong word רופס is where you put tefilin on the head.

    #1767774

    Reb Eliezer
    Participant

    Should be:

    טור אורח חיים הלכות שבת סימן שיח
    היד סולדת בו דהיינו כל שכריסו של תינוק נכוית בו

    #1767788

    Reb Eliezer
    Participant

    The baby’s stomach burns at a cooler temperature than the hand.

    #1767799

    Reb Eliezer
    Participant

    The source is:

    תלמוד בבלי מסכת שבת דף מ עמוד ב
    והיכי דמי יד סולדת בו? אמר רחבא: כל שכריסו של תינוק נכוית

    רבינו יהונתן מלוניל על הרי”ף מסכת שבת (לפי דפי הרי”ף) גמרא דף יט עמוד א
    יד סולדת בו, נכוית מלשון ואסלדה בחילה, כלומר מתחממת הרבה יותר מדאי עד שמושך ידו לאחור מדאגה שלא תכוה

    Too pull away the hand is before it actually burns.

    #1767843

    DovidBT
    Participant

    The baby’s stomach burns at a cooler temperature than the hand.

    How was this determined?

    #1767883

    Reb Eliezer
    Participant

    I think it is more sensitive,

    #1767887

    Reb Eliezer
    Participant

    I think you pull away your hand from the heat when the baby’s stomach would actually be scalded.

    #1767890

    DrYidd
    Participant

    halakha is not a good discussion topic for blogs. nor is science. a human with a temperature of 105 degrees can possibly survive, at least for a while. a body temperature of 110 degrees means you are about to die. i would not suggest trying it.

    #1767920

    Meno
    Participant

    a human with a temperature of 105 degrees can possibly survive, at least for a while. a body temperature of 110 degrees means you are about to die

    What shaychus?

    #1767937

    Neville ChaimBerlin
    Participant

    “a body temperature of 110 degrees means you are about to die.”
    That has nothing to do with what we’re talking about. Running a fever of 110 and dipping your hand in 110 degree water are two very different things.

    “I think it is more sensitive,”
    How is this determined? Wouldn’t the gemara imply that scalding a baby and reflexively retracting a hand occur at the same temperature? Either way, the baby thing doesn’t really change my kasheh. I firmly do not believe 110 Fahrenheit would scald anything. It really isn’t that hot.

    #1767994

    DrYidd
    Participant

    meno, to the comments that five degrees are not that critical. it is both illogical and disrespectful of the halakhic system.

    #1768181

    Neville ChaimBerlin
    Participant

    “to the comments that five degrees are not that critical. it is both illogical and disrespectful of the halakhic system.”
    I don’t think you understood the context. Whatever vadai yad soledes bo is, 5 degrees less than that should feel uncomfortable, not like prime bath temperature. But, yes, you’re right: whatever YSB is, there’ll always be something 5 degress less that isn’t.

    I think the thread has well established that YSB isn’t actually based on when your hand reflexively retracts. Now the question is, when and why did it become universally accepted that YSB doesn’t mean what it sounds like it means?

    #1768208

    GAON
    Participant

    Nev,
    I will quote a similar approach by the Darkei Teshuvah:

    בעל “דרכי תשובה” (על שולחן ערוך יורה דעה, סימן קה) ציטט את שיטת בעל הלכות גדולות, ולפיה חלב הנחלב מבהמה נידון כ”צונן”. ובכן, בדקו ומצאו כי טמפרטורת החלב בשעת החליבה היא כ45 מעלות צלזיוס. מכאן כתבו רבים, שחימום עד לשיעור זה בוודאי אינו מוגדר יד סולדת, שכן הבה”ג הגדירו “צונן”. ובכן, אין לקבוע ששיעור יד סולדת הוא 45 מעלות צלזיוס, אלא שפחות מ45 מעלות צלזיוס בוודאי איננו שיעור יד סולדת

    The above point is that fresh milk which is basically warm i.e. body temperature of the above 45c is considered “cold” regarding halacha.

    Another interesting definition of YSB, Harav Ovadia quotes the Ben Ish Chai :

    הרב עובדיה זצ”ל (לוית חן, אות מח) מביא את הגדרת הבן איש חי :”כל מקום שזה החמין ראוי לשתיה או לאכילה שאין האדם נמנע מכח ריבוי חמימותו הרי זה לא נחשב יד סולדת בו”. כלומר, אם אתה יכול לשתות או לאכול את התבשיל מיידית ללא נשיפה לקירור וכו’ אז אינו יד סולדת בו. אם אתה שותה אותו לאט מחמת החום כמו תה רותח אז מוגדר היד סולדת.

    #1768603

    harimak
    Participant

    When I set the mikvah (men’s) temperature at 100, most people refused to enter, and those that did sounded like a cat’s choir at midnight.
    Now imagine how that would feel on a baby’s belly.
    110 is definitely a very plausible degree. (This is not a measure of “boiling”.)

    #1768871

    Neville ChaimBerlin
    Participant

    Goan:

    That was actually very helpful. So, what we call “yad soledes bo” is actually “vadai aino mugdar yad soledes.” It’s the highest temperature we can definitely still consider not yad soledes bo. So, 46 degrees C could potentially still be not yad soledes, but there’s no rayah in halachah. The highest temp that’s provably not yad soledes if 45 on account of the cow milk.

    I’m not sure I follow the Ben Ish Chai you brought. Isn’t it just describing the pashut definition of yad soledes bo without giving an actual temperature or mashal?

    #1768884

    Reb Eliezer
    Participant

    Nev, the highest temperature where the baby’s belly is scalded but not the hands, so you pull it away before it.

    #1768917

    Neville ChaimBerlin
    Participant

    “Nev, the highest temperature where the baby’s belly is scalded but not the hands, so you pull it away before it.”

    Yes, we know. We’re talking about how the exact temperatures are derived. I personally think the best answer is the Darchei Teshuva that Gaon just brought, which also seems to be how Rav Shlomo Zalman held according to Avi K above.

    It is, however, possible that I like that answer because I’m not a farmer and therefore just take their word for it that milk leaves a cow at 113 degrees. A little web research does show that animals have higher body temperatures than humans. It seems like goats might be hotter than cows; I wonder if they went by cows or the most hot kosher milk animal.

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