22-08-2013, 11:31 PM
Vildt gode billeder - skyd flere ヅ
James Dowling kommer i det efterfølgende med en god (og ikke mindst rigtig) forklaring på hvorfor Rolex begyndte med hvidguldsmarkeringer.
[i]
"Hi all;
The white gold circular indices were introduced during the period when Rolex was using tritium as an exciter.
You have to understand what the luminous indices on the dial were made of then, we call it 'tritium' but in fact that was the smallest of the three ingredients. The actual shine comes from a phosphor, which lights up when 'charged'; you can charge it with direct light but the usual way it was charged was by emission of beta particles during the decay of the tritium.
The stuff you see on the dial is well under 1% tritium, 3 or 4% phosphor and the rest is a binder to hold the important ingredients together. The crucial thing for the binder is that it has to go on as a liquid (essentially a paint) but has to become a solid fairly quickly. This is done by firing the completed dial in a low temperature oven, this forces all the liquid in the binder out, but it leaves it in a hygroscopic state; that is it loves water, it wants to revert to its original state. This doesn't easily happen because watches are not naturally wet; however, if the watch is kept in a humid atmosphere for any length of time, the binder will absorb moisture from the atmosphere & as it sucks in the moisture it will expand. This is the cause of what is sometimes called 'Tritium Spread', seen here on this Submariner.
It was in order to prevent this spread that Rolex went to using white gold frames around the tritium indices, they used white gold, not because it is shiny or expensive or blingy, but rather because it is a so called 'noble metal' which is not affected by the phosphor in the lume.
James Dowling.
James Dowling kommer i det efterfølgende med en god (og ikke mindst rigtig) forklaring på hvorfor Rolex begyndte med hvidguldsmarkeringer.
[i]
"Hi all;
The white gold circular indices were introduced during the period when Rolex was using tritium as an exciter.
You have to understand what the luminous indices on the dial were made of then, we call it 'tritium' but in fact that was the smallest of the three ingredients. The actual shine comes from a phosphor, which lights up when 'charged'; you can charge it with direct light but the usual way it was charged was by emission of beta particles during the decay of the tritium.
The stuff you see on the dial is well under 1% tritium, 3 or 4% phosphor and the rest is a binder to hold the important ingredients together. The crucial thing for the binder is that it has to go on as a liquid (essentially a paint) but has to become a solid fairly quickly. This is done by firing the completed dial in a low temperature oven, this forces all the liquid in the binder out, but it leaves it in a hygroscopic state; that is it loves water, it wants to revert to its original state. This doesn't easily happen because watches are not naturally wet; however, if the watch is kept in a humid atmosphere for any length of time, the binder will absorb moisture from the atmosphere & as it sucks in the moisture it will expand. This is the cause of what is sometimes called 'Tritium Spread', seen here on this Submariner.
It was in order to prevent this spread that Rolex went to using white gold frames around the tritium indices, they used white gold, not because it is shiny or expensive or blingy, but rather because it is a so called 'noble metal' which is not affected by the phosphor in the lume.
James Dowling.
Cheers, Jesper
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