#Radium luminous paint mod

The ‘Circle P’ indicating its use can be clearly seen on Seiko quartz chronographs supplied to the British MOD and promethium notably found its way onto the hands and dials of the US Navy Tornek-Rayville Blancpains, leading to an alarming radiation warning being engraved on the case back. Promethium and tritium were the next candidates for use as low-grade radiation sources. Later dial details added by Rolex such as ‘underlines’ show that the replacement dials had been checked to be ‘strontium-free’. It also found its way into the Bakelite bezels of the early 6542 causing them to be recalled and changed for anodised aluminium. Over in Switzerland, strontium was used on dials by a number of manufacturers including Rolex. Luminous paint was invented in 1902 by William J Hammer who first mixed radium with zinc sulphide, but he failed to patent his creation and lost out to George Kunz at Tiffany & Co., who did. Radium is a curious element, always warmer than its surroundings due to the radiation it emits, but what suited it to watchmaking was the fact it glowed and could be used to impregnate the hands and dials of watches and clocks making them glow at night.

The substance that put the ‘time’ into night-time was discovered by Marie and Pierre Curie in 1898. In 1680 Daniel Quare created repeating watches that could tell time in the dark to the nearest quarter of an hour, but it would be a further 70 years before time to the nearest minute would be possible and even then, these marvels of miniaturisation were only available to the privileged rich. Before widespread public and domestic lighting, dark meant dark and passing hours might be marked by a chiming clock if you were rich enough, or close enough to a church. This means that early watches, however finely made or accurate, were at best part-time timepieces. Part 2: LumeĪ watch is only as good as its ability to tell you the time. Delve into the history of dial design and the elements that make up some of the most famous watch faces of our time.

Radium luminous paint