A. Lange & Söhne has revealed the first of its new timepieces to be launched at January’s SIHH watch fair in Geneva: the Grand Lange 1 Lumen. A limited edition of 100 pieces, the watch features two firsts for the German luxury brand: a luminous outsize date and a partially transparent dial.
The watch comes in a platinum case and has a dial with sections made of semi-transparent sapphire crystal; only the outer ring and the surfaces of the subdials (one for hours and minutes, the other for small seconds) are made of blackened silver. The sapphire areas reveal the disk mechanism of the outsize date underneath the dial. The big date, a hallmark of the Lange 1 family of watches, is the first one that glows in the dark, along with the time and the power reserve display.
The Lange outsize date was inspired by the Five-Minute Clock in Dresden’s Semper Opera House, to which brand namesake Ferdinand A. Lange contributed his expertise in 1841. Like that of the clock, the date mechanism of a Lange watch maximizes the date display by means of two separate elements: the ring-shaped units disk with the numerals 0 to 9 switches once a day, until the transition from the 31st to the 1st, in which it stands still for a day. The “tens” cross, with the numerals 1 to 3 and a white blank space, advances by only one increment every 10 days. When it displays the 3, the tens cross advances to the blank space after only two days. The irregular switching sequence is controlled by two program wheels with a precisely calculated toothing pattern.
To solve the technical challenge of ensuring maximum luminosity for the date display, even immediately after the daily switching operation, Lange’s developers coated the tens cross with a white luminous compound before imprinting the black numerals, then used transparent glass imprinted with black numerals for the units disk, which rotates in front of a luminous background.
The sapphire areas of the dial are treated with a special coating that blocks most of the visible spectrum of light but not the invisible ultraviolet light spectrum, which means that UV radiation can pass through to the luminous surfaces of the outsize date unhindered. This is what the makes the date platform, with its manually applied perlage, normally seen only by the watch-maker during the assembly process, visible to the watch’s owner. The small, overlapping circular graining, produced by hand using a rotating abrasive peg, is normally concealed underneath the dial.
The movement, Lange’s manufacture Caliber L095.2, can be seen through the sapphire caseback. A. Lange & Söhne started using this new, manually wound caliber for the Grand Lange 1 just this year. The omission of a second mainspring barrel and a new arrangement of the parts reduced the overall height of the caliber without compromising any of the power reserve, and allowed for a dial arrangement in which none of the off-center subdials — for hours and minutes, small seconds and power reserve — need overlap each other or the outsize date display.
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