Radium

Thread: Radium

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  1. #1
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    Question Radium

    I have a question I could not find an answer for on the 'Net.
    Radium (used as ingredient in Luminous paint for dials in the old days) is Radioactive all the time (very long half live).
    Why do you need to "charge" it under a lamp or sun to get the max. and most long lasting lume?
    Should it not be luminous at the same strength at all times, not depending on the charging?

  2. #2
    Member JohnF's Avatar
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    Re: Radium

    Hi -

    Radium hands, like tritium lume, doesn't need to be "charged" under a UV light source. Both shine on their own.

    Other lumes, such as SuperLuminova etc., must be charged, as their composition requires that a certain quanta of light be effectively absorbed, sort of like a battery, in order for them to have long-term endurance.

    Ra226, a breakdown product of U238, has a half-life of 1602 years. Tad overkill to use it for lume.

    Radon gas is a by-product of Radium decay.

    Tritium has a half-life of 4500±8 days (approximately 12.32 years). The tritium itself doesn't actually glow, but the radiation emitted causes phosphors to glow. It occurs naturally (H3), but not in meaningful amounts, and was first manufactured in 1934.

    SuperLuminova and its derivatives are modified crystals that act as a light "bank". They have no meaningful half-life, but must be "charged" up.

    JohnF
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  3. #3
    Member Eeeb's Avatar
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    Re: Radium

    True Radium dials do NOT need to be 'charged' under a light. Dials which do are either not true radium or are a mixture of radium and 'normal' lume paint.
    "Forever is composed of nows." - Emily Dickinson

    "The watch has to be surrounded by a history.
    You need more than just a great design. You need to create an atmosphere around the product.
    Who is the company behind it? Why are they using this material?
    People need to be able to identify the watch with themselves. It's based on emotion." - Ralph Furter

    ...that's just my opinion and I've been wrong before and will be again and might be now!

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  5. #4
    Member Eeeb's Avatar
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    Re: Radium

    Quote Originally Posted by JohnF View Post
    ...
    Ra226, a breakdown product of U238, has a half-life of 1602 years. Tad overkill to use it for lume....
    Ah John, but it was done!! ... then folks began to realize the dangers of radioactivity exposure to the workers... And alternatives became viable.

    Here is an interesting website on it's use and the exposure problem.
    "Forever is composed of nows." - Emily Dickinson

    "The watch has to be surrounded by a history.
    You need more than just a great design. You need to create an atmosphere around the product.
    Who is the company behind it? Why are they using this material?
    People need to be able to identify the watch with themselves. It's based on emotion." - Ralph Furter

    ...that's just my opinion and I've been wrong before and will be again and might be now!

  6. #5
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    Re: Radium

    Aha! So it is the zink sulfite that emits the light! And it can deteorite! That explains why only the hands are luminous on my watch! The paint is much thicker, so I guess it will take longer for the zink sulfite to get damaged!
    Interesting site, Eeeb!
    Thanks all! Janne

  7. #6
    Member gatorcpa's Avatar
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    Re: Radium

    Quote Originally Posted by Janne View Post
    That explains why only the hands are luminous on my watch! The paint is much thicker, so I guess it will take longer for the zink sulfite to get damaged!
    If the colors of the lume are different, it's likely that someone had the hands relumed (or replaced) at some point in the watch's life. It was much easier to refinish the hands than the dial.

    Here one from my collection where this process has been done.



    This one probably had the hands redone with radium paint years ago. It no longer glows at all.

    Hope this helps,
    gatorcpa

  8. #7
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    Re: radium

    hi everybody I read the link eeeb attached regarding the radium in watches and noticed I have a watch with the same symbol on it ,, its a Phasar Quartz should I be concerned ?
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  9. #8
    Member Eeeb's Avatar
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    Re: radium

    Quote Originally Posted by osiris View Post
    hi everybody I read the link eeeb attached regarding the radium in watches and noticed I have a watch with the same symbol on it ,, its a Phasar Quartz should I be concerned ?
    yes... it means you should not eat the watch.
    "Forever is composed of nows." - Emily Dickinson

    "The watch has to be surrounded by a history.
    You need more than just a great design. You need to create an atmosphere around the product.
    Who is the company behind it? Why are they using this material?
    People need to be able to identify the watch with themselves. It's based on emotion." - Ralph Furter

    ...that's just my opinion and I've been wrong before and will be again and might be now!

  10. #9
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    Re: radium

    "Not eat the watch" -

    A bit more info on your watch: The information on your watch indicates that the watch contains tritium (3H) which is a radioactive isotope of hydrogen. It does not contain radium. Note that the radiation emitted by tritium is very low energy and does not even penetrate the watch case.

  11. #10
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    Re: radium

    On the Phasar, where is the Tritium? It looks like a Digital watch! LCD?

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