How long does it take for a dial to have strong radium burns to the dial where the hands have sat for a long time? Any ideas?
Thanks, makes senseIt will depend what sort of material the dial is coated with.
A ceramic dial would probably hardly ever show signs of burns, but a painted dial could, depending what type of paint.
I have played with gamma radiation of polymers and composites a while back, some requires a very minimal dose, others are pretty much immune to radiation.
Polyester for sure didn't like radiation, polyamide wasn't too happy neither. Opposed to common belief, PTFE didn't seem to be harmed.
Carbon composites also seems less prone to damage, which would in many cases equal black paint.
A big variable here is that the age of radium burns isn't necessarily a function of the age of the watch, but rather of how long the watch has been stopped. So in theory, a 1930 watch that was used consistently up until recently may not have any radium burns at all, while a 1950 watch that was put in a drawer in 1952 may have significant burns.
But the dial is not burnt, just the plastic crystal.
Nope - not to the extent one would expect.I do see a slight haze around the numbers on the pocket watch.
Agreed.Nope - not to the extent one would expect.
The horizontal escapement of radium must be equal to vertical. Yet vertically has in both cases imprinted the crystal with the number
Agreed.I think you also have to consider how the hands are filled with the lume. If you have skeletal (cathedral or baton) then the relationship between the lume and the dial is different if you have a solid hand with a "lume well". Think about how tough the dials often look on 1950s watches which had the lume applied to the backs of solid hands which back lit them (I forget the trade names for this...).