Urwerk Clads its Ultimate (and Final) UR-105 Edition in Tantalum—the UR-105 TTH

written by James Malcolmson, photos provided by Urwerk Geneve

With the release of the new The UR-105 TTH, Urwerk is closing out the production of its much-coveted UR-105 collection. And in many ways, the 12 pieces of this edition, all clad in ultra-durable tantalum, are the ultimate expression of the UR-105’s identity. Originally conceived to “shield” the precious satellite system within, the UR-105’s have sprung rotating guards to the satellites as well as elaborate case covers, each with differing and intriguing finish codes. The complexity and philosophic design perfectly illustrates the brand’s ethos. With the use of tantalum, the literal and figurative shield to the movement is taken to an even higher level.

“Tantalum is a very special metal. Its name comes from Tantalus, one of Greek mythology’s bad boys,” offers Urwerk co-founder Martin Frei. “Tantalum is precious, rare, and extremely painful to machine and finish. We made an UR-110 out of tantalum a few years ago – a first that almost was the last. The team made me promise never to use it again because tantalum ‘eats’ our CNC machines’ bits. It destroys them, reducing their life by a factor of three. But I love its blue-gray luster. The UR-105 TTH comes with a protective cover, a breastplate that protects the mechanism. Tantalum is a perfect protective shield against corrosion. Hence its name “TTH” stands for Tantalum Hull”

Fortunately, Urwerk’s drive for perfect aesthetics usually trumps the practicalities, and the brand proceeded to commission the laborious machining of 12 cases. “Tantalum is one of the most URWERK-ian metals I know of,” says co-founder Felix Baumgartner. “It is dark, almost anthracite colored, a shade which is an integral part of URWERK’s aesthetic signature.”

Activating the sliding “tongue” of the UR-105 TTH opens the hull to reveal its mechanics, featuring a satellite time indication built on a new skeleton carousel. The latter supports four-hour satellites, each displaying three hour numerals that rotate in turn along the minute track, providing both analog and digital time displays.

A power reserve indication and digital seconds complete the information on the dial. The digital seconds displaying the seconds in ten-second increments is particularly remarkable. To make it as light and as ephemeral as possible, the seconds disk was made using the LIGA photolithography process and the marker is openworked. The total weight of the display is less than 0.10 grams.

On the back, two turbines regulate the movement’s automatic winding system, which can be easily adjusted using a small lever according to how active the wearer is. In the "FULL" position, the slightest movement of the wrist is enough to wind the mainspring. In “STOP” mode, the automatic winding system is deactivated and the UR-105 is manually wound. A third intermediate position, “RED” (for REDUCED), moderates winding to minimize excessive tension and wear.

The weight of tantalum makes the UR-105 TTH a beautiful object, substantial and pleasing to hold. Its distinctive octagonal form features deep streaks along its entire length. It is angular, geometric, and symmetrical with strong influence from the Art Deco style piece, this may be the last opportunity to acquire a piece in this distinctive model series.

As Felix Baumgartner. explains: “At URWERK we took radical decisions very early on: deciding to remain independent at all costs and limiting our growth despite all the advice to the contrary were among the most important. To continue staying true to ourselves, to remain URWERK, we make less than 150 pieces per year. This means that we reluctantly have to ‘kill’ a collection to bring a new creation to life. And time for the UR-105 CT is now running out.”