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Crown

Aquadura cork-sealed crown

Probable

Mido's proprietary crown sealing system, using a cork element that swells slightly in contact with water to tighten the seal. Genuinely unusual — almost every other water-resistant crown in this catalog relies on synthetic gaskets — and the source of a service behaviour an examiner needs to know about.

Part reference

Brand
Mido
Material
Metal crown with a cork sealing element

Documented variations

Classification

FactoryDocumented as shipped from the factory for this reference and period.PeriodNot original to this watch, but correct for its production period.ServiceFitted by the manufacturer's own service network. Not a defect.AftermarketThird-party part. Affects originality, not authenticity.ModifiedGenuine parts in a configuration the factory did not sell. Affects originality and value, not authenticity.CounterfeitDeceptive reproduction intended to pass as genuine.UnknownEvidence on file does not settle the question.

  • Serviced cork seal, sealing correctly

    FactoryProbable

    Whole production

    The intended state. The cork is intact and swells on contact with water as designed.

  • Dried and shrunken cork on a long-stored watch

    FactoryProbable

    Whole production

    Cork dries out when a watch sits unworn for years, and the crown loses its seal. A period Mido failing a pressure test is very often in this state. It is a service condition, not a failed specification, and reporting it as evidence that the water-resistance claim was never true would be wrong.

  • Crown replaced with a conventional gasketed type

    ServiceProbable

    Whole production

    A common repair where the original cork component was unavailable. The watch is sealed and working; it no longer carries the Aquadura system. A service finding affecting originality.

Open questions

OpenComponent compatibilityMedium

Aquadura service parts availability

Are cork sealing components still supplied for period Aquadura crowns, and what is the accepted service practice where they are not?

Scope Determines whether a substituted conventional crown on a period Mido should be read as a reasonable repair or as an avoidable loss of originality — a judgement the catalog currently records without being able to justify either way.

Documented on these references

Provenance of this record

Sources & Evidence

Secondary sourceCollector research

Mido collector research on the Multifort, monocoque cases and Aquadura servicing

Collector communities and watchmakers

Accessed
2026-08-19

Cited for

This referenceProbable
Primary sourceManufacturer documentation

Mido — collection specifications and technical material

Mido (Swatch Group)

Accessed
2026-08-19

Cited for

This referenceHigh confidence
View source ↗

Last verified: Not yet reviewed