Altmann × Isotope Osaka Cloisonné Enamel

Isotope Watches presents the Altmann × Isotope Osaka Cloisonné Enamel, a highly limited collaboration that transforms an unexpected source of urban design, Japanese manhole covers, into a work of horological art.

Limited to just five pieces, the watch features a hand-crafted grand feu cloisonné enamel dial, created through an intensive process that required nearly a full year of development and production.

Each watch is accompanied by a signed copy of Manhole Covers of the World, the book that inspired the collaboration.

From Urban Infrastructure to Horological Art

For years, Isotope founder José Miranda had been fascinated by the remarkable artistry of Japanese manhole covers. These everyday objects are part of urban infrastructure, yet many display extraordinary levels of graphic sophistication, cultural symbolism, and civic pride.

The idea of translating these designs into watchmaking remained unresolved until Miranda encountered Manhole Covers of the World, a book by designer and illustrator Björn Altmann. The book documents the typography, composition, and visual language of manhole covers with the same attention typically reserved for more traditional forms of design.

A short conversation between Miranda and Altmann revealed a natural connection between the book and a potential watch project. What followed was the creation of an extremely small series of watches that brings together two artistic expressions: Altmann’s documentation of manhole cover design and Isotope’s expertise in unconventional watch dials.

The Osaka Manhole Cover

The dial is based on a municipal manhole cover from Osaka, Japan, featuring Osaka Castle at its center.

Flowing water motifs and cherry blossoms in bloom surround the castle, symbolizing the city’s connection to water and the cyclical renewal of the seasons. The Japanese characters 大阪市 (Ōsaka-shi) appear on the original cover, identifying it as an official municipal design rather than a decorative reinterpretation.

This direct connection to civic infrastructure is precisely what makes these objects compelling. They are functional, public, and quietly artistic.

Translating the design into a watch dial was not about simplification but about fidelity. Every line, color, and proportion was carefully adapted to preserve the spirit of the original design while reinterpreting it through traditional watchmaking techniques.

Cloisonné Enamel: A Year in the Making

Because of the complexity of the pattern, producing the cloisonné dials proved exceptionally demanding. To keep the project commercially viable while maintaining depth and definition, nearly 12 months were spent developing the production process.

Each dial is built on a solid sterling silver base and crafted using traditional grand feu cloisonné enamel techniques.

Fine silver wires form the structure of the design, while multiple layers of vitreous enamel are applied and fired individually in a kiln. Each color requires its own application and firing stage. Due to the complexity of the design and the repeated kiln cycles required, completing the five dials took almost a full year. In the end, only five dials were successfully completed.

Dial Production Process

1. CNC Engraving

The solid silver dial base is CNC-engraved to create recessed sections that define the design's structure.

2. Hand-Applied Silver Wires

Fine silver wires are shaped and positioned by hand to create the cloisonné cells.

3. Enamel Filling

Vitreous enamel powder is carefully placed into the spaces between the wires.

4. Kiln Firing at 850°C

The dial is fired in a kiln at approximately 850°C, where the enamel melts and bonds permanently to the silver base.

After each firing, the enamel shrinks, and the surface becomes uneven. Additional enamel is applied, and the dial is fired again. This filling and firing process is repeated around ten times until the dial reaches the correct thickness and depth.

5. Polishing and Inspection

The dial is polished to achieve a perfectly smooth surface. If air bubbles or micro-holes appear, the dial must return to the kiln for additional enamel application and firing.

Each dial undergoes extensive hand finishing and strict quality control before approval.

About Björn Altmann

Björn Altmann is an independent designer, illustrator, and typographer with more than 17 years of experience in the creative industry.

With a strong focus on branding and a longstanding interest in watches, he has contributed to the watch industry as an illustrator, dial designer, and type specialist.

After many years working in London, both within agencies and independently, he has collaborated with major international brands.

Within the watch industry, his work includes projects with TAG Heuer, Ollech & Wajs, Benjamin James, TWAC, De Rijke, and Bremoir, as well as special projects for collectors of Cartier, Audemars Piguet, and Andersen Genève. He has also worked alongside designer Emmanuel Gueit.

Altmann recently collaborated with TAG Heuer on the book TAG Heuer Carrera: The Race Never Stops, producing illustrations of more than 500 Carrera references.

His work has also appeared in projects for Fears, Watches of Knightsbridge, Hodinkee, and others.

He is the author of Manhole Covers of the World, published by Swiss publisher Niggli.

Technical specifications

Altmann × Isotope Osaka Cloisonné Enamel

Limited edition of 5 pieces

Each watch is delivered with a signed copy of Manhole Covers of the World by Björn Altmann

Case

• Material: 316L stainless steel, mirror finish
• Diameter: 38mm
• Thickness: 10mm
• Lug-to-lug: 44.5mm
• Anti-reflective domed sapphire crystal
• Screw-in sapphire exhibition case back
• Water-resistant to 100 meters

Dial and hands

• Cloisonné enamel dial

Movement

• Calibre I-7
• Swiss-made modified ETA Peseux 7001
• Manual winding
• Number of jewels: 17
• Frequency: 3 Hz, 21'600 vph
• Power reserve of 42 hours

Functions/Indications

• Hours, minutes, small seconds

Strap and buckle

• 20mm quick-release leather strap with signed steel buckle

MSRP

• GBP 3'600 (excl. taxes) with White FKM CTS strap
• GBP 3'800 (excl. taxes) with White FKM CTS strap + bracelet with quick release and micro-extension

For more information, please visit isotopewatches.com