As consumers increasingly pursue healthier lifestyles and refined taste experiences, sparkling water (soda water) has become a popular beverage choice worldwide. The satisfying "hiss" sound when opening a chilled bottle of sparkling water is not accidental, it is made possible by a precisely engineered 18mm aluminum bottle cap, which must withstand internal pressure while preserving freshness.
What Is an 18mm Aluminum Cap for Sparkling Water?
An 18mm aluminum cap typically refers to an aluminum screw-type closure with an inner diameter of 18 mm, specifically designed for glass bottles. Its primary functions are to withstand internal carbonation pressure, ensure absolute sealing, and provide convenient opening.
This type of closure is commonly known as a ROPP cap (Roll-On Pilfer Proof cap) or aluminum screw cap. The most widely used specification is 28x18 mm, where the outer diameter is approximately 28 mm, and the inner diameter (neck finish diameter) that engages with the bottle is 18 mm.
The cap is extremely lightweight, weighing approximately 4 grams per piece, and is manufactured from aluminum alloy with a specialized liner to ensure reliable sealing.
Liner options: PE, Saranex, or Sarantin liners, designed to enhance sealing performance and prevent leakage.
Product Specifications
| Product Name | Aluminum Screw Cap / Aluminum ROPP Cap / 18mm Aluminum Cap |
| Diameter | 18 mm |
| Height | 28 mm (customizable) |
| Material | Aluminum Alloy 8011 / 3105 |
| Liner Type | PE / Saranex / Sarantin |
| Surface Treatment | Coated or printed, custom colors available |
| Pressure Resistance | ≥ 3 bar (suitable for carbonated beverages) |
| Weight | 1.5-2.0 g (depending on material and thickness) |
| Packaging | Carton + pallet |
| Applications | Sparkling water, cocktails, carbonated drinks |
| MOQ | 80,000 pieces (negotiable) |
Structural Features of 18mm Aluminum ROPP Caps for Sparkling Water
1.Precision Screw Thread Design
The aluminum cap features precision-formed threads that tightly engage with the bottle neck, creating an airtight seal and preventing leakage. High thread accuracy ensures sealing stability even under high carbonation pressure.
2.High-Performance Liner Materials
Food-grade PE or composite liners (Saranex / Sarantin) improve sealing reliability and prevent direct contact between the beverage and metal, ensuring flavor integrity and product safety.
3.Anti-Corrosion Surface Treatment
Through anodizing or coating processes, the cap achieves enhanced corrosion resistance. Custom printing and branding are also available, combining protective performance with visual appeal.
4.Lightweight Construction
The 18mm aluminum cap is lightweight, reducing material costs while improving packaging, transportation, and production-line efficiency.
Typical Applications
Carbonated beverages (soda, cola, sparkling water)
Mineral water and small-size purified water bottles
Health drinks, juices, and functional beverages
Small-capacity sample bottles and portable beverage packaging
