Certina Caliber 15-20: A Transitional Movement Bridging Tradition and Reliability

The Certina Caliber 15-20 represents an evolution in Certina’s manual-wind movement lineage, crafted during a period of industrial refinement and post-war resurgence in Swiss watchmaking—likely introduced in the early to mid-1950s. This caliber served as a slightly larger and more robust alternative to the earlier 13-ligne series, optimized for more substantial watch cases and improved long-term performance.

A manual-wind, time-only movement with sub-seconds, the 15-20 was engineered for daily durability, serviceability, and mid-range affordability, placing it among the dependable workhorse calibers of its time.

Technical Specifications

The larger diameter gave the 15-20 enhanced dial stability and gear train spacing, contributing to consistent timekeeping and reduced friction between components.

Construction and Mechanical Design

The 15-20 was a logical extension of Certina’s hand-wound series, maintaining familiar architecture while incorporating incremental mechanical improvements. Key features include:

• Swiss lever escapement with a generous balance wheel

• Manual mainspring barrel with strong torque delivery

• Full bridge or three-quarter plate configuration

• Sub-seconds display driven by a dedicated fourth wheel

• Long-lasting parts, well-oiled pivot surfaces, and rugged steel pinions

It features 17 functional jewels, lubricating the gear train, escape wheel, pallet fork, and balance pivots, helping ensure longevity and smoother power flow.

Application in Certina Watches

The Certina 15-20 was used in a range of mid-century wristwatches aimed at men who wanted a reliable, no-nonsense Swiss timepiece. These watches typically featured:

• Case sizes between 34 mm and 36 mm

• Sub-seconds dial at 6 o’clock, reflecting pre-automatic design aesthetics

• Steel or gold-plated cases with minimal ornamentation

• Clean dials, often with numerals or baton hour markers

• Slim profiles, aided by the relatively flat construction of the 15-20

It’s worth noting that while the caliber had no calendar function or automatic winding, it remained highly respected for its rugged simplicity.

Watchmaker Service Notes

The 15-20 is considered easy to service and well-suited to restoration. Its relatively open layout, wide bridges, and strong part tolerances make it appealing for vintage watch technicians.

Servicing Tips:

• Use Moebius 9010 for escapement and gear train lubrication

• Ensure crown wheel and ratchet teeth are free of wear or corrosion

• Replace mainspring when power reserve or amplitude appears weak

• Balance assembly and Incabloc shock springs should be carefully inspected

The movement responds well to regulation and, when clean, typically achieves ±10 to 15 seconds per day accuracy.

Collector Appeal

While less famous than automatic or date-equipped Certina calibers, the 15-20 has a strong following among vintage purists and restoration experts. It offers:

• A solid mechanical platform for mid-century dress watches

• Authenticity for period-correct restorations

• Durable architecture with excellent parts interchangeability

• Aesthetically timeless watch designs from the 1950s

For collectors who appreciate manual-wind watches with vintage soul, the 15-20 is a solid candidate—often found at accessible prices and with original components intact.

Conclusion

The Certina Caliber 15-20 is a fine example of functional Swiss watchmaking, bridging the gap between pre-war hand-wind calibers and more modern constructions. Its reliable build, well-balanced performance, and classic design have earned it a place in the toolkit of watchmakers and on the wrists of discerning vintage enthusiasts. Whether you're restoring a family heirloom or adding to a collection, the 15-20 continues to deliver dependable mechanical charm in a straightforward, serviceable package.