Everything you need to know about 29mm crown caps
Answers to the most frequently asked questions about our 29mm crown caps for sparkling wines, Champagne and craft beers.
Questions about 29mm crown caps
Not familiar with some technical terms? Check our Technical Glossary.
29mm crown caps with integrated bidule are metal closures used during secondary fermentation of Méthode Traditionnelle sparkling wines, Champagne and craft beers. The bidule is a small food-grade plastic insert that collects yeast sediment in the bottle neck, making disgorgement easier.
Mida crown caps withstand pressures between 7 and 10 bars, the standard required for Méthode Traditionnelle and Champagne production. Every batch is tested with traction and pneumatic tightness analysis before shipment.
Mida Capsules manufactures 29mm crown caps in three materials: aluminium, stainless steel AISI 304 and tin-plated steel. Stainless steel is ideal for ageing in humid environments such as cellars and caves.
Yes. Mida Capsules offers screen-printing customisation with the client's logo, available in standard colours: gold, green, blue, red and grey. Minimum batch quantities are agreed directly with our sales manager.
Mida crown caps are delivered in boxes of 5,000 pieces on wooden euro pallets. For screen-printed custom caps, the minimum batch is agreed directly with our sales manager.
Certifications and testing
The O2TR (Oxygen Transmission Rate) is measured according to ASTM F 1307-20 by the ACCREDIA-accredited laboratory CSI — IMQ Group, at 23±1°C. Mida caps achieve values below 0.001 cc/package/24h — among the lowest available for secondary fermentation closures.
Yes. All materials — aluminium, stainless steel AISI 304 and tin-plated steel — are MOCA certified (EC Regulation 1935/2004), guaranteeing absolute neutrality and zero chemical transfer.
Stainless steel AISI 304 is the mandatory choice for ageing in caves, underground cellars or high-humidity environments. Its corrosion resistance guarantees crimping integrity throughout secondary fermentation, even over multiple years.
How to choose the right 29mm crown cap for your sparkling wine or craft beer
Choosing a crown cap is a technical decision that directly affects the quality of the final product. This guide helps you identify the most suitable 29mm crown cap for your production process.
1. Choose the material: aluminium, stainless steel AISI 304 or tin-plated steel
Aluminium — the most economical and versatile choice for standard production in dry environments. Ideal for short ageing (up to 18 months) and craft beers with rapid refermentation.
Stainless steel AISI 304 — mandatory for ageing in caves, underground cellars or high-humidity environments. The preferred choice for producers of Champagne with extended lees ageing.
Tin-plated steel — the best compromise between mechanical resistance and cost. In our experience with Italian and French wineries, it is the most widely used choice for productions with ageing between 24 and 36 months.
Discover all available materials →2. Verify compatibility with your capping system
Check that the crimping diameter is compatible with your capper. Mida caps are calibrated between 31.3 and 31.6 mm depending on the material. The same caps are compatible with both wine and beer bottles with standard 29mm finish.
What is crimping? →3. Check MOCA certification and food compliance
Any closure in contact with wine, sparkling wine or beer must be MOCA certified (EC Regulation 1935/2004). Always request official documentation on the compliance of materials and the internal liner. Mida caps are MOCA certified and accompanied by a technical data sheet for each batch.
What is MOCA certification? →4. Evaluate O2TR to protect organoleptic evolution
The O2TR (Oxygen Transmission Rate) is the most critical technical parameter for Méthode Traditionnelle sparkling wines, Champagne or craft beers with extended refermentation. Choose caps with values below 0.001 cc/package/24h according to ASTM F 1307-20, tested by ACCREDIA-accredited laboratories.
What is O2TR? →5. Consider screen-printing customisation
Customising the crown cap with your logo in screen printing adds value to every bottle during ageing. Mida Capsules offers customisation in five standard colours — gold, green, blue, red and grey — for agreed minimum order quantities. Screen printing does not alter the technical properties of the cap in any way.
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Our technical team answers all your questions about 29mm crown caps.