Do Jefferson Golden Hour Clocks have radioactive paint?

Discussion in 'Clock Repair' started by THTanner, Jul 18, 2019.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. THTanner

    THTanner Registered User
    NAWCC Member

    Jul 3, 2016
    2,228
    117
    63
    Male
    Carson City, Nevada
    Country Flag:
    Region Flag:
    Someone I respect - in a different forum - who has been working clocks for many years - and whose father is a nuclear engineer and scientist - tested three Jefferson Golden Hour clocks and found that the X1 Scintillation scale went to the peg (maxed out on the scale)

    The emission is Beta particles from the paint flaking or chipping off. The danger is if you inhale that dust.

    I suspect that originally these clocks were well lacquered over the paint in which case the paint dust will not occur.

    I am not a nuclear scientist by any means, but have worked in hospital nuclear material labs where these sensors were used to monitor radiation levels. They are quite accurate and sensitive and I suspect this gentleman was getting valid readings.

    Has anyone else ever heard of this?

    tom

    Scintillation counter - Wikipedia
     
  2. bruce linde

    bruce linde Technical Admin
    NAWCC Member

    Nov 13, 2011
    5,409
    469
    83
    oakland, ca.
    Country Flag:
    Region Flag:
  3. Willie X

    Willie X Registered User

    Feb 9, 2008
    11,709
    600
    113
    Should be easy enough to check.
    WIllie X
     
  4. bruce linde

    bruce linde Technical Admin
    NAWCC Member

    Nov 13, 2011
    5,409
    469
    83
    oakland, ca.
    Country Flag:
    Region Flag:
    my geiger counter has a broken mainspring... or i would have checked already
     
  5. bruce linde

    bruce linde Technical Admin
    NAWCC Member

    Nov 13, 2011
    5,409
    469
    83
    oakland, ca.
    Country Flag:
    Region Flag:
    apparently this has been discussed many times... the numbers and stripes on the centers of the hands had luminescent paint. the luminescence is typically gone but the radiation has a half life of 1600 years

    jefferson clock radioactive paint - Google Search
     
    THTanner likes this.
  6. THTanner

    THTanner Registered User
    NAWCC Member

    Jul 3, 2016
    2,228
    117
    63
    Male
    Carson City, Nevada
    Country Flag:
    Region Flag:
    The analysis this man did showed that the radioactive dust had migrated, probably through the air or handling contact, to pretty much every surface on the three clocks he tested.
    This led him to the concern that it seems loose enough to become airborne. Contact with the skin is no real concern for this low energy particle, but inhaled it can cause serious problems. Tritium releases a similar low energy particle that does no harm to the skin, but causes cancer if inhaled or swallowed. And the tritium sights and other lighted items are safe as long as they are handled properly.

    I wonder what the proper handling of these clocks might be. A simple wipe down with a damp cloth would seem to limit most of the airborne dust potential. But as the customer brings it into the shop uncovered there could be some danger?
     
  7. bruce linde

    bruce linde Technical Admin
    NAWCC Member

    Nov 13, 2011
    5,409
    469
    83
    oakland, ca.
    Country Flag:
    Region Flag:
    ahhh... i’ve had mine running for years and rarely move or touch it... but will do so with a different perspective from here out.
     
  8. leeinv66

    leeinv66 Moderator
    NAWCC Member

    Mar 31, 2005
    9,469
    116
    63
    Male
    Industry Specialist
    Launceston Tasmania
    Country Flag:
    Region Flag:
    There is some danger in getting out of bed in the morning. Unless you are in the habit of licking your clocks, I think you are pretty safe.
     
  9. novicetimekeeper

    novicetimekeeper Registered User

    Jul 26, 2015
    8,958
    423
    83
    Male
    retired and on my second career
    Dorset
    Country Flag:
    Region Flag:
    If it is radium, which seems likely, it is gamma and alpha that are the main sources of the count. If it is tritium it would be pretty much spent by now with a half life of 12.5 years.
     
  10. bangster

    bangster Moderator
    NAWCC Member

    Jan 1, 2005
    19,083
    292
    83
    utah
    Country Flag:
    Region Flag:
    Who'd a thunk it?
     
  11. THTanner

    THTanner Registered User
    NAWCC Member

    Jul 3, 2016
    2,228
    117
    63
    Male
    Carson City, Nevada
    Country Flag:
    Region Flag:
    I was curious about what was used for the glowing hands and could not find a reference. Radium was the most common for awhile, and you are right about the decay into mainly Alpha with some Gamma from Radium. He referenced Beta as the problem he detected but did not explain the source.

    The best explanation I could find states

    "Radioluminescent paint consists of a radioactive material mixed together with a luminescent crystalline powder. The first radioactive material to be used was radium-226 (Ra-226), but it hasn't been employed since the 1970s, at least in the U.S. Today, tritium (H-3) and promethium-147 (Pm-147) are the radionuclides of choice. Other radionuclides have also been used, e.g., strontium-90 (Sr-90) and carbon-14 (C-14). Zinc sulfide powder has been the most widely used luminescent material.

    The light emitted by the paint is due to the radiation energy deposited in the luminescent crystals by alpha and/or beta particles. Next to no light is due to gamma rays."

    From that I suspect it may have been the Zinc Sulfide powder, which tends to flake and get dislodged more easily.


    My reference to Tritium was just as an example of similar "safe" radiation unless ingested.
     
  12. THTanner

    THTanner Registered User
    NAWCC Member

    Jul 3, 2016
    2,228
    117
    63
    Male
    Carson City, Nevada
    Country Flag:
    Region Flag:
    I wonder if there is any reason to try to explain the possible danger to customers, especially if they have children in the house?
     
  13. shutterbug

    shutterbug Moderator
    NAWCC Member

    Oct 19, 2005
    40,238
    622
    113
    Male
    Self employed interpreter/clock repairer
    Iowa
    Country Flag:
    Region Flag:
    The alarm about luminescent hands was raised when the women who painted them began to get cancer. They would shape the brush tip to a point by using their lips. I've never heard of a case where just being in proximity to the hands caused any issues. We are exposed to radiation by many natural sources every day.
     
  14. gmorse

    gmorse Registered User
    NAWCC Member

    Jan 7, 2011
    10,319
    1,085
    113
    Male
    Retired from Xerox
    Breamore, Hampshire, UK
    Country Flag:
    Region Flag:
    Hi shutterbug,

    Including the radon gas which is itself a radioactive decay product of radium.

    Regards,

    Graham
     

Share This Page