I was not able to find anything on the subject of lume on Shabbos.
I asked my LOR. He is not familiar with it either.

Lume is a paint they use on watch dials that charges from light and then shines in the dark temporarily.

If the watch was in the dark for an extended period of time, the dials will not be charged, and bringing it to the light will cause the dials on the watch to change color.

Is there an issue of "tzovayah", dyeing, when wearing this type of watch in the light on Shabbos?

  • 1
    This is called photoluminescent paint
    – Rabbi Kaii
    Commented Mar 13, 2023 at 15:01
  • ohr.edu/ask_db/ask_main.php/34/Q1 mutar according to Rav Scheinberg AH
    – Rabbi Kaii
    Commented Mar 13, 2023 at 15:05
  • 3
    can you explain the question please. What do you want to do with the watch? Commented Mar 13, 2023 at 15:23
  • 2
    What would the potential problem be? Commented Mar 13, 2023 at 21:35
  • Isn't this a form of "glow in the dark", I know this kind of watches, and I believe that the watch-owner does not have to do anything to let the watch glow up so to speak.
    – Shmuel
    Commented Mar 14, 2023 at 17:26

1 Answer 1


The Orchos Shabbos, Volume 1, ch. 15, footnote 96 (page 456), says that it is permitted to go outside with a watch with hands covered in luminescent material, even though this will cause them to give off light when they are in the dark. But when one does an action whose sole purpose is to change the color, for example a thermometer, it is forbidden because then his action gets the name "dyeing".

(The thermometer that he is discussing is the kind that he mentioned earlier in that footnote, which is the kind that is placed on the forehead and changes color based on the temperature.)

וכן מותר לצאת אל האור בשעון שמחוגיו מצופים זרחן אף שמחוגים אלה יאירו מעתה בחשכה, אבל כאשר עושה פעולה מיוחדת שכל מטרתה לשנות את הצבע,וכגון לגבי מד-חום, הרי זה אסור דאז מקבלת פעולתו שם של מעשה צביעה.


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