Swiss independent URWERK, a favorite of Iron Man actor Robert Downey Jr, is killing-off its UR-105 model to make way for a new design.

The UR-105 TTH or Tantalum Hull is a final, limited run of 12 pieces with a case made from tantalum, a particularly hard precious metal with a density similar to platinum.

“Tantalum is a very special metal,” URWERK co-founder Martin Frei explains. “It’s 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, reducing their life by a factor of three. But I love its blue-gray luster.”

The “Hull” of the title is the retractable breastplate that shields the movement and can be released by pushing a sliding catch, revealing the brand’s “satellite time” indication, a sci-fi take on the classic wandering hour complication. A carousel with four hour satellites, each displaying three revolving hour numerals, rotates against a minute track so that the current hour always points to the current minutes.

A seconds disc, which rotates in ten-second increments, sits at the left of the dial while a power reserve indication sits to the right. The UR-105 also features a unique automatic winding system, regulated by two air turbines and adjustable depending on the lifestyle of the wearer, whether active of sedentary.

URWERK’s decision to retire the model stems from the brand’s desire to make no more than 150 watches each year and points to the imminent arrival of a new design.
Urwerk presented the new UR-105 Tantalum Hull (TTH), the model that marks the end of the 105 Collection. In fact, with a production of just 150 pieces per year, the Swiss brand has to replace a collection in order to bring new creations in their catalogue.
The new watch comes in a “soap bar” case in titanium and tantalum that is 39.5 mm wide, 53 mm long and 17.8 mm high.

Characterised by a fascinating blue-gray luster, Tantalum is a precious metal that is very difficult to machine and finish. Rarer than gold, harder than steel, and highly corrosion-resistant, tantalum is an alternative to platinum for its inertness. Thanks to its high density, it is extremely resistant to acids.

A limited edition of just 12 pieces, the UR-105 TTH reveal its mechanics by sliding the catch on the top of the case: an openworked carousel carries four satellites, each bearing three numerals for the hours that rotate in turn along the minute track, providing both analog and digital time displays.
Introduced first in 2017, to mark URWERK’s 20th anniversary, Felix Baumgartner and Martin Frei have just announced the end of series version of the UR-105CT, with UR-105 TTH “Tantalum Hull”. Why so? Simply put, for a watchmaking endeavor such as URWERK’s, which to this day produces a nominal 150 watches per year, some creations from within the fold must be brought to a conclusion, in order to make room for the next greater timepiece to forward the brand’s watchmaking story.
In its final form, the UR-105 CT has been given a tantalum shroud with less aggressive ribbing down its front, which somehow makes the watch more rounded than the original. Part of the reason why the UR-105 TTH has been given this lesser ribbed design could very simply be because of challenges involved in milling tantalum.
Says Martin, “Tantalum is a very special metal. Its name comes from Tantalus, one of Greek mythology’s bad boys. 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. Pure magic!”

Seeing it in the pictures though, it has to be said that it’s almost criminal that more URWERK watches aren’t rendered in tantalum. But conceding to the difficulty, the UR-105 TTH will be produced in a limited run of just 12 pieces.
“Tantalum is a precious metal weighing approximately the same as platinum. It has a solid presence on the wrist,” adds Felix. “To machine it is a nightmare, but it has incomparable beauty. Tantalum is one of the most URWERK-ian metals I know of. It is dark, almost anthracite colored, a shade which is an integral part of URWERK’s aesthetic signature”
The Urwerk UR-105 TTH ‘Tantalum Hull’ is the last iteration of the brand’s highly acclaimed UR-105 series. Partially housed in tantalum, a rare metal that is very difficult to machine and polish, the appearance of the material and its various attributes made it a worthy choice for Urwerk, a brand that is not afraid of tackling technical challenges.
Founded in 1997, Urwerk’s models stand out from the congested watch market thanks to the brand’s distinctive design language, playful use of materials and high-end finishing. A few years ago, the Swiss brand lent me a UR-210 model and I wore it for an extended period lasting several weeks. The horological behemoth proved comfortable to wear and its wandering hours display was highly intuitive to read.

Having marvelled at the UR-210 and noting its various attributes, I was somewhat surprised to hear the brand call a halt to production. Thereafter, it was not long before the firm released the UR-220 Falcon Project. At first glance, the watch appeared similar to the UR-210 and certainly some of its genetic code had been carried over to the newer model. However, the UR-220 Falcon Project was hand-wound, slimmer and its curving case bestowed a superior ergonomic fit.
At the heart of the company’s paradigm is an overriding desire to deliver advancement. The firm has made several different models over the years and has never been afraid to slay an existing reference in order to make way for a new addition to the Urwerk family. Furthermore, the marque has always strived to keep its model range limited in size, a trait that was recently touched upon by Felix Baumgartner. The Maison’s genius watchmaker remarked, “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.”

Once a model has joined the current line-up, the firm invariably releases a number of animations throughout its life. Colour, textures and materials are all subject to co-founder Martin Frei’s penchant for creative expression. Martin Frei and Felix Baumgartner have employed materials from a variety of sources, some ordinarily used for aerospace or medical applications. With many large watch brands, an animation is a comparatively inexpensive step, however, for a brand like Urwerk, making approximately 150 watches per annum, selecting a different case material is incredibly expensive. Put simply, when producing small quantities of components, Urwerk won’t benefit from the same economies of scale enjoyed by a big brand that has an annual production figure running into six figures.
Now, the time has come to say goodbye to the UR-105, a popular model that has sired many offspring. The Maison has played with a variety of materials and finishes, ingeniously creating a new look each time. Indeed, if one contrasts the UR-105TA Clockwork Orange, the UR-105CT Streamliner and the UR-105CT Maverick, they all share the same jawline but look markedly different.

The UR-105’s swansong is the Urwerk UR-105 TTH ‘Tantalum Hull’. The case combines titanium and tanatalum. This latter metal is rare, corrosion-resistant, hypoallergenic, robust and exhibits a blue-grey appearance. Certain grades of titanium are highly problematic to machine, causing tools to wear out more readily. Moreover, milling speeds have to be reduced to prevent heat damage, thereby heightening production times and inevitably costs. According to the brand, tantalum also presents many challenges to the CNC machine operator. Nevertheless, Urwerk has repeatedly demonstrated over the years that it is not afraid to confront technical obstacles in order to achieve the look or performance it seeks. The wandering hours display features a new skeleton carousel and the brand has made the seconds disc using LIGA technology.

As I look at the Urwerk UR-105 TTH ‘Tantalum Hull’, I lament its passing and I perfectly understand the reason why many horophiles will crave one of the 12 pieces available. However, based on experience, I predict there will be many more delights to come from this progressive brand.
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 analogue 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.