Put simply, a Geiger counter cannot differentiate between various radioactive materials.įor example, Radium-226 has a half-life of 1600 years, meaning that after 1600 years its emission rate will be halved. Since a whole range of different radioactive materials have been used, this makes identification using a tool as blunt as the Geiger counter fraught with problems. Further, the amount of radioactive decay from one material to the next can be very different. Why is this relevant with respect to the use of a Geiger counter? Well, different radioactive materials give off different types of emission. So if different radioactive materials were used, why is that important for Geiger counter usage? So, to clarify, the second conclusion that can be drawn is that a wide range of radioactive materials were in use in the pre-Tritium era. It is now known that other Radium variants (for example. Most typically, when one reads about the use of Radium on watch dials, what is being referred to is Radium-226. The 6542 GMT was, of course, being sold before this scare, which begs the question of how far back was Strontium being used? Finally, not all Radium is the same. The Strontium-90 scare with the Rolex GMT 6542 originated in the late-1950s. It is similarly documented that the US Navy responded to the 1960 AEC ruling by replacing Radium with Strontium-90. For example, as mentioned above, the use of Promethium-147 was still permitted under the 1967 International Standard. In fact, it is known that a whole range of different possible radioactive materials were being used. The second conclusion, however, is that just because Tritium was probably not in use before 1960 does not mean that Radium-226 was the only other possible luminous material being used. Rolex didn’t just use Radium-226 - they used all sorts of different radioactive materials Having said this, it seems a reasonable first conclusion to draw that pre-1960, dials are unlikely to have contained Tritium. As ever with Rolex, there is no definitive truth. It is known that some US motor manufacturers started using Tritium on its instrument dials from 1959.

Realistically, one could argue that some watches from the early 1960s will have had Tritium, yet at the same time other watches - even from the same reference - from the late 1960s could well have still been produced with Radium. Furthermore, the 1967 International Standard on luminous materials still permitted the use of Radium in watches, albeit recommending the use of Tritium or Promethium-147. The US army still used Radium-226 in its dials well into the late 1960s. The US military were notably patchy in their replacement of radium dials. Although the Atomic Energy Commission (AEC) ruled on 13th December 1960 that Tritium would replace the use of Radium in timepieces, one cannot identify a specific time-line for when Radium was stopped in the manufacture of watch dials. It is in this area where there is most contention and as such more value in making the picture clearer. Given the enormity of the subject matter, this article will focus specifically on the use of Geiger counters in evaluating pre-Tritium Rolex dials. This article will explain why the Geiger counter has no place in the process of evaluating a watch. The answer is that there are simply too many variables that can affect the use of a Geiger counter to provide anything reliable. It is not a question of experience or of having tested many watches. The short answer is that the Geiger counter is most unlikely to be able to offer any reliable insight into the evaluation of the radiation on a watch’s dial. I will give two versions of the answer a short one and a more detailed one. This article aims to answer a very simple question Is the Geiger counter a reliable tool in the evaluation of radiation on a watch dial? It is a very simple question, yet the answer is anything but simple.

Radium dial watch