Most aluminium bottle caps, from 30 × 60 mm wine closures to 20 mm injection-vial seals, are deep-drawn from 8011 closure sheet in H14 or H16 temper, roughly 0.17 – 0.25 mm thick. The alloy combines enough strength to hold thread and torque with the low earing and clean drawing a high-speed cap press needs. This guide explains cap types, sizes, liners, material specifications and how to specify caps or cap stock, which Metline supplies to bottlers and closure makers worldwide.
An aluminium cap starts as a flat, lacquered sheet less than a quarter of a millimetre thick. It is punched into a disc, drawn into a cup, decorated, lined and, for roll-on caps, threaded on the bottle itself by the capping head. Every step depends on the sheet behaving the same way from coil to coil.
8011 is an aluminium-iron-silicon alloy. The iron and silicon form fine intermetallic particles that strengthen the metal and refine its grain without the need for heat treatment, so the sheet gains strength through cold rolling and partial annealing (the H14 and H16 tempers). Compared with pure 1xxx aluminium, 8011 is stiffer and more resistant to denting and stretching under capping loads; compared with 3105 or 5052, it is cheaper and draws with very low earing when the rolling and annealing schedule is controlled.
That is why 8011 has become the default closure alloy for roll-on pilfer-proof (ROPP) caps on wine, spirits, water and edible oil, and is widely used for pharmaceutical vial seals and twist-off lids. 3105 is the usual alternative where a cap maker wants a little more strength or a different drawing response; we cover it in our 3105 closure strip guide.
The word "cap" covers several quite different closures. They share the same base metal but differ in how they seal, how they show tampering and which liner they carry.
Supplied as plain, unthreaded shells. The capping head presses the cap onto the bottle and rolls the thread and the tamper band into the metal so they follow the glass exactly. Used on still wine, spirits, water, juices and oils.
The familiar 30 × 60 mm screw cap for still wine, with a long decorative skirt that imitates a capsule over a cork. The liner controls how much oxygen reaches the wine.
Caps with formed threads, applied by screwing rather than rolling. Common on small bottles, cosmetics and some food jars.
Crimp seals for 13, 20 and 32 mm injection vials. A rubber stopper does the sealing; the aluminium skirt is crimped under the vial lip to hold it. Flip-off caps add a coloured plastic button.
Caps with a scored tear strip and ring, used on infusion bottles, sauces and some beverages where the cap is removed without tools.
Wide-mouth closures for jars and cans, made from lacquered 8011 or 3xxx/5xxx strip depending on diameter and pressure.
Cap sizes are given as diameter × height in millimetres. The diameter must match the neck finish of the bottle; the height depends on the thread length and on how much decorative skirt the brand wants.
| Cap size (mm) | Typical type | Usual application |
|---|---|---|
| 13, 20, 32 | Crimp seal, flip-off cap | Injection and infusion vials |
| 18 × 12, 20 × 12, 22 × 15 | ROPP / screw cap | Miniatures, small spirit and oil bottles, cosmetics |
| 25 × 43 | ROPP | Some spirit and liqueur bottles |
| 28 × 15, 28 × 18 | ROPP / screw cap | Mineral water, soft drinks, juices on glass or PET |
| 28 × 32 to 28 × 44 | ROPP | Spirits and premium waters |
| 30 × 35 | ROPP | Wine, fortified wine, spirits |
| 30 × 60 | Long wine cap | Still wine (Bordeaux and Burgundy style bottles) |
| 31.5 × 44, 31.5 × 60 | ROPP | Spirits, vodka, whisky and premium oils |
| 35 – 38 mm | ROPP / screw cap | Juices, large water bottles, oil and syrup |
Exact neck finishes are defined by bottle-industry drawings (for example the wine finishes used for 30 × 60 mm caps). Always send the bottle neck drawing with an enquiry so the cap height, thread and liner position can be matched.
The chemistry below is the registered Aluminum Association composition for 8011, which EN 573-3 also lists as EN AW-8011A with very similar limits. Food-contact closures are usually also required to meet EN 602, which limits certain elements in aluminium intended to touch food.
| Element | Limit (wt %) | Effect |
|---|---|---|
| Silicon (Si) | 0.50 – 0.90 | Forms Al-Fe-Si particles with iron; strengthens and refines grain |
| Iron (Fe) | 0.60 – 1.00 | Main alloying element; raises strength and controls earing |
| Copper (Cu) | ≤ 0.10 | Impurity |
| Manganese (Mn) | ≤ 0.20 | Minor strengthening |
| Magnesium (Mg) | ≤ 0.05 | Impurity |
| Chromium (Cr) | ≤ 0.05 | Impurity |
| Zinc (Zn) | ≤ 0.10 | Impurity |
| Titanium (Ti) | ≤ 0.08 | Grain refiner |
| Others each / total | ≤ 0.05 / 0.15 | |
| Aluminium | Remainder | About 97.3 – 98.9 % |
| Temper | Typical gauge (mm) | Tensile strength (MPa) | Earing | Typical use |
|---|---|---|---|---|
| 8011-H14 | 0.17 – 0.25 | 125 – 165 (yield about 110 – 150) | ≤ 2 – 3 % | ROPP caps for wine, spirits, water, oil |
| 8011-H16 | 0.18 – 0.25 | Higher than H14; limits per EN 485-2 or contract | ≤ 3 % typical | Vial seals, stiffer caps, pull-ring caps |
| 8011-H18 | 0.15 – 0.25 | Highest of the three; per contract | As agreed | Flat lids, tear-off components |
Ranges are typical closure-stock values from mill specifications and EN 485-2 / EN 546-2 limits; the exact contract figures, and whether they are measured before or after a paint-bake simulation, are agreed per order and reported on the mill certificate.
Metline supplies 8011 closure sheet and strip in coil or cut sheet, mill finish or pre-lacquered, to closure makers and cap producers. Bottlers and brand owners can share their cap specification with us so the cap stock is matched to it. Material is shipped worldwide from our base in Mumbai with full material certification.
The aluminium shell holds the closure on and shows whether it has been opened, but the liner is what actually seals against the bottle lip. Choosing the right liner matters as much as choosing the metal.
| Liner type | Properties | Recommended for |
|---|---|---|
| PE / EPE foam | Cushioning, good leak-tightness, economical | Still water, juices, edible oil, sauces |
| PVDC-faced film (Saranex-type) | Moderate, controlled oxygen transmission | Wines intended for drinking within a few years |
| Tin-foil barrier (Saran-tin type) | Very low oxygen transmission | Wines for long cellar ageing, aroma-sensitive spirits |
| Induction foil liner | Hermetic seal welded to the lip; clear tamper evidence | Nutraceuticals, powders, condiments shipped long distances |
| Rubber / bromobutyl stopper | Pierceable, sterilisable, chemically inert | Injection vials (used with crimp seals) |
| PVC-free flowed compound | Seals under pressure and pasteurisation | Carbonated drinks, twist-off food jars |
Liner choice also drives regulatory compliance: liners and lacquers that touch the product must be approved food-contact or pharmaceutical materials in the destination market, for example under US FDA 21 CFR or EU Regulation 1935/2004.
Base coats in gold, silver, white, black or Pantone-matched colours; matt, gloss, metallic and soft-touch finishes. The inner lacquer protects the metal from the product.
Top and side printing by offset lithography on flat sheet before drawing, or by dry offset and screen on finished caps; multi-colour logos and batch codes.
Raised or recessed logos on the top panel and hot-foil stamping for a premium look on wine and spirits caps.
Vertical knurls on the skirt improve grip and hide minor marks; patterns vary by cap maker and brand.
Tamper bands, hidden marks and serialised printing help fight counterfeiting of high-value spirits.
Bulk cartons for hopper feeding, layer packing for automatic lines, or palletised and shrink-wrapped for export.
| Market | Typical caps | What the closure must do |
|---|---|---|
| Still wine | 30 × 60 mm long cap; 30 × 35 mm for some styles | Hold a consistent oxygen ingress rate over years of storage, upright or on its side |
| Spirits | 31.5 × 44, 31.5 × 60, 28 – 30 mm ROPP | Prevent evaporation and leakage, resist alcohol, show tampering, look premium |
| Water and soft drinks | 28 mm and 38 mm ROPP or screw caps | Run at high line speeds and, for carbonated drinks, hold CO2 pressure |
| Pharmaceuticals | 13, 20, 32 mm crimp seals and flip-off caps | Hold a sterile stopper, survive autoclaving or terminal sterilisation, colour-code products |
| Edible oil and condiments | 28 – 38 mm ROPP, often with a pourer | Resist fats, allow controlled pouring, guard against refilling |
| Food jars | Twist-off lids and easy-open ends | Keep a vacuum through pasteurisation and resist acidic foods |
Aluminium caps also suit sustainability goals. Aluminium can be recycled repeatedly without losing its properties, and caps left on glass bottles are increasingly recovered in glass and metal sorting streams. Brands that move from a cork and capsule to an aluminium screw cap also remove a separate foil or PVC capsule.
For cap makers, the main material-related causes of scrap are uneven earing, gauge variation across the coil width, poor flatness and lacquer adhesion failures. Ask for earing to be tested in the delivered (or paint-baked) condition and for gauge to be reported across the width, not just at the centre.
Delivery terms are quoted EXW, FOB, CIF or DAP. Cap stock ships in coils on wooden pallets or in cases, eye-to-sky or eye-to-wall, wrapped against moisture.
The iron and silicon in 8011 make it stronger and stiffer than 1xxx aluminium at the same gauge, so caps resist denting and hold their thread under capping load, while the alloy still draws cleanly with low earing. It is also economical and widely available as closure stock.
Most ROPP and screw caps are drawn from sheet about 0.20 – 0.25 mm thick; small caps and vial seals often use about 0.17 – 0.20 mm. The exact gauge depends on cap diameter, height and the cap maker's tooling.
A ROPP cap arrives as a plain shell; the capping machine rolls the thread and tamper band into it on the bottle, so it fits each neck exactly. A pre-threaded screw cap already has its thread and is screwed on.
For wines drunk within a few years, PVDC-faced film liners give a small, controlled oxygen ingress. For wines meant for long ageing, tin-foil barrier liners let in very little oxygen. Winemakers choose the liner to suit the wine style.
Yes, when made from food-contact grade alloy (for example to EN 602) and coated with approved inner lacquers and liners. The product touches the lacquer and liner, not bare metal, and those materials must comply with the rules of the destination market.
Yes. Aluminium can be recycled repeatedly without loss of quality, and caps are recovered in metal sorting streams. Leaving the cap on the bottle often helps it get captured rather than lost as a small loose item.
Yes. We supply 8011 closure sheet and strip in H14, H16 and other tempers, slit to your width, mill finish or pre-lacquered, with mill test certificates, to closure makers worldwide.
Send your cap stock gauge, width, temper and coating, and the cap type it is for. Our team will reply with a material specification and delivered price.
