Reply With Quotehad always wondered what the "t" meant thank you :idea:
In order for timepieces to be read in the dark, a luminescent material is laid on the dial indexes and hands. Generally speaking, the emission of light is either of photoluminescent type (determined by a exciting luminous radiation) or of radioluminescent type (determined by the radioactivity of the material).
Timepieces featuring radioluminescent emission are mostly designed for very specific uses : military watches, professional divers watches, etc. In this case, the use of radioactive material is strictly defined by ISO 3157 Standard which allows only two types of radionucleides : tritium (3H) and promethium (147 Pm). It is important to specify that these radionucleides emit a radiation of low energy.
ISO 3157 Standard allows an optional marking for timepieces emitting less than a certain value. The marking may be made on the dial as follows :
deposits activated by tritium : T
deposits activated by promethium : Pm
On the other hand, timepieces with a higher value, such as divers' watches, must be marked as follows :
deposits activated by tritium : T 25
deposits activated by promethium : Pm 0,5
The indication "T Swiss made T" means that the watch is Swiss and contains a certain quantity of tritium that emits less than 227 MBq (7,5 mCi).The indication "Swiss T<25" means that the watch is Swiss and contains a certain quantity of tritium that emits less than 925 MBq (25 mCi).
Most of the Swiss watches use a light emission of photoluminescent type. Some of them bear the optional marking "L Swiss Made L" to indicate it.
had always wondered what the "t" meant thank you :idea:
ktmog6uk
marchingontogether!
Every now and again you will run across a "Ra SWISS Ra" dial.
But, radium was becoming a rarity by the time this convention was starting to be established in the early to mid-sixties.
"Ha Swiss Ha"
Nice one Noah thanks for that
Thanks Noah, have to admit I didn`t know the details although I understand the principle from my Science studies in the distant past. A superb concise article.
Paul
Originally Posted by noah
That's very nice, did you hear about all the poor ladies who's job it was to paint the dial ?
Most if not all came down with some kind of Radiation paisioning
Yes.
But, less than 1% actually died from direct radiation effects, although a very high percent (compared to the rest of the population) came down with leukemia and other forms of cancer.
Some of the girls used the radium paint in non-standard ways such as painting their finger nails, or teeth to shock and amaze their boyfriends and family.
The importance of that case (originally brought about by five women, although, I believe the settlement was expanded to include all of the painters past and present) was not about the hazards of radium, which was generally known as a radioactive substance, but that of the duty of an employer to ensure workplace safety and communicate which substances are potentially harmful. As well as the right of employees to sue their employer for failing to a) provide proper protective equipment, and b) failing to inform employees about dangerous workplace materials or equipment.
The US Radium Corporation (the employer) did not inform the women of the dangers, which lead to the above dangerous uses of the paint.
That particular dial was made nearly 40 years after the "Radium Girl's" case had been settled.
You learn something new every day
Did you read about the Radium Girls too ..
I thought the paining of the teeth interesting
On A Panerai, it's the type of 'Lume' they use on the dial - either T or L. T is more desirable as it changes colour over time and developes a Patina...
Thanks for this - very informative
Never knew about the 'Ra Swiss Ra' dials, interesting stuff.
AFAIK the only man to doink a 'radium' girl was Captain James T Kirk :D
Respect the past, live the present, protect the future
Ya she was all Green, I think he had a few Purple one's too
Well they're all purple.... oh nevermind that :lol:
I'm not as think as you drunk I am.
Useful infomation. Thanks so much!!!
Posting Permissions