Altmann × Isotope Osaka Cloisonné Enamel
"For many years, I wanted to create a watch inspired by the remarkable artistry of Japanese manhole covers.
These objects belong to everyday urban life, yet they often display an extraordinary level of graphic sophistication, cultural symbolism, and civic pride. For a long time, however, I could not find the right way to approach the idea.
When I came across Björn Altmann’s book Manhole Covers of the World, it became clear that I was not alone in recognising the artistic value of these designs. The book documents their typography, composition, and visual language with the same respect normally reserved for more conventional forms of art.
After a short conversation with Björn, we realised there was a natural way to bring two artistic expressions together: his book and a very small series of watches." - Jose Miranda, Isotope Co-Founder
That conversation eventually led to the creation of the Altmann × Isotope Osaka Cloisonné Enamel.
From Osaka to the Dial
The dial reproduces a municipal manhole cover from Osaka, Japan, featuring Osaka Castle at its centre.
The design is framed by flowing water patterns and cherry blossoms in bloom. These elements reference Osaka’s relationship with water and the symbolism of seasonal renewal.
The Japanese characters cast into the original cover read 大阪市 (Ōsaka-shi), meaning Osaka City. This identifies the design as an official municipal manhole cover rather than a decorative reinterpretation.
This connection to real civic infrastructure is precisely what makes these designs so compelling. They are functional objects created for everyday use, yet they quietly carry layers of cultural identity and graphic artistry.
Translating this design into a watch dial was not about simplifying it. Instead, the goal was to preserve the spirit of the original while adapting it faithfully to traditional watchmaking techniques.
Cloisonné Enamel
To reproduce the Osaka design properly, the dial had to be made using grand feu cloisonné enamel.
Each dial begins as a solid sterling silver base, which is first CNC-engraved to create recessed sections that define the structure of the design.
Fine silver wires are then shaped and applied by hand to form the cloisonné cells.
These cells are filled with vitreous enamel powder, which is then fired in a kiln at approximately 850°C. During firing, the enamel melts and bonds permanently to the silver base.
After the first firing, the enamel shrinks, leaving the surface uneven. More enamel must then be applied before the dial returns to the kiln.
This filling and firing process is repeated around ten times until the dial reaches the correct thickness and colour depth.
Once complete, the dial is polished and carefully inspected. If air bubbles or micro-holes appear, the dial must return to the kiln for further enamel work.
Because of the pattern's complexity and the number of firing cycles required, completing the five dials took almost a full year.
A Collaborative Project
The watch was created in collaboration with Björn Altmann, an independent designer, illustrator, and typographer with more than 17 years of experience.
Björn has worked extensively within the watch industry, contributing to projects for brands including TAG Heuer, Ollech & Wajs, Benjamin James, TWAC, De Rijke, and Bremoir, as well as special order projects for collectors of Cartier, Audemars Piguet, and Andersen Genève.
He also recently collaborated with TAG Heuer on the book TAG Heuer Carrera: The Race Never Stops, producing illustrations of more than 500 Carrera references.
Björn is the author of Manhole Covers of the World, published by the Swiss publisher Niggli.
Only Five Dials
Due to the complexity of the dial construction and the intensive handwork required, only five cloisonné dials were completed.
Each watch owner will also receive a signed copy of Manhole Covers of the World by Björn Altmann.
Technical Details
The watch is built on the Isotope Mercury platform.
Case
316L stainless steel
Diameter
38mm
Thickness
10mm
Lug to Lug
44.5mm
Crystal
Domed sapphire with anti-reflective coating
Caseback
Screw-in sapphire exhibition caseback
Water Resistance
100m / 10 ATM
Movement
Calibre I-7
Swiss-made modified ETA Peseux 7001
Manual winding
17 jewels
21,600 vph
42-hour power reserve
Functions
Hours, minutes, small seconds
Strap
20mm leather strap with signed steel buckle
Availability
The Altmann × Isotope Osaka Cloisonné Enamel is limited to five pieces worldwide.
Each watch includes a signed copy of Manhole Covers of the World by Björn Altmann.
The watches are available for purchase on March 24 at 3:00 PM GMT.
They are now ready to ship. GET YOURS HERE!