Aluminum foil can be classified according to thickness, product form, temper, surface condition, and subsequent processing or finish. These classifications help buyers, converters, and manufacturers select the appropriate foil for packaging, lamination, electrical, heat-exchanger, battery, and forming applications.
1. Classification by Thickness
| Class | Thickness | Typical Use |
|---|---|---|
| Thick foil (heavy gauge) | 0.10–0.20 mm | Rigid containers, cable wrapping, insulation facing |
| Single-zero foil (medium gauge) | 0.01 to <0.10 mm | Household foil, pharmaceutical packaging, flexible packaging |
| Double-zero foil (light gauge) | <0.01 mm, typically 0.005–0.009 mm | Candy wrapping, lidding, cigarette packaging, selected electrical applications |
The terms single-zero foil and double-zero foil are commonly used in the aluminum industry to describe different gauge ranges, although exact definitions can vary by market and company specification.
There is also no single universal international boundary between "light-gauge" and "heavy-gauge" foil. Some industry practices use approximately 40 µm as a reference point, but buyers should follow the applicable product standard and agreed specification. For thickness tolerances and product requirements, standards such as GB/T 3198, ASTM B479, or the relevant EN specification should be confirmed according to the application.
2. Classification by Form
Roll foil: Supplied in coils or rolls and widely used as feedstock for printing, coating, laminating, slitting, forming, and other continuous converting processes. Roll foil is the dominant form for industrial aluminum foil production.
Sheet foil: Supplied as pre-cut sheets for applications where continuous coil processing is not required. Sheet dimensions and flatness should be specified according to the intended use.
3. Classification by Temper
Hard foil: Aluminum foil in a harder, strain-hardened condition, generally without final full annealing. It provides higher strength and stiffness but may require appropriate surface cleaning or degreasing before printing, coating, or laminating, depending on the rolling-oil condition and converter requirements.
Semi-hard foil: A partially softened condition with mechanical properties between hard and fully annealed foil. It is used where a balance between strength, flexibility, and forming performance is required.
Soft foil: Fully or substantially annealed foil with high flexibility and formability. Soft foil is widely used for household foil, flexible packaging, lidding, pharmaceutical packaging, and other forming or laminating applications.
Temper should not be selected independently of the final process. The required hardness, tensile strength, elongation, forming performance, and surface cleanliness should all be considered.
4. Classification by Surface Condition
One-side bright foil: Commonly produced through the final stages of rolling two layers together. The outer surfaces develop different appearances, resulting in one relatively bright side and one matte side. This process is widely used for thin household and packaging foil.
Two-side bright foil: Produced when the aluminum is rolled as a single layer against the work rolls, allowing both sides to develop a relatively bright appearance. The final appearance depends on roll surface condition, rolling parameters, foil thickness, and finishing requirements.
The distinction between bright and matte surfaces is primarily a result of the rolling process and does not normally indicate a fundamental difference in the aluminum alloy itself. Surface appearance requirements should be specified separately when appearance is important.
5. Classification by Finish
Plain foil: Aluminum foil supplied without additional printing, coating, embossing, or lamination after rolling. Depending on the product specification, it may also be referred to as mill-finish or uncoated foil.
Embossed foil: The foil surface is mechanically embossed with a regular or customized pattern. Embossing can increase surface area, improve appearance, and provide additional stiffness or texture.
Composite foil: Aluminum foil laminated with materials such as paper, plastic film, or other substrates. Composite structures are widely used in flexible packaging and insulation applications.
Coated foil: The foil is coated with lacquer, resin, paint, polymer, or another functional material to improve corrosion protection, heat sealing, adhesion, insulation, or printability.
Colored foil: A coating or printing process gives the foil a uniform colored surface for decorative, branding, or identification purposes.
Printed foil: Text, graphics, logos, patterns, or other information are printed on the foil. Depending on the printing process and product requirements, multi-color printing can be used for high-quality packaging and branding applications.
6. Alloy Selection Note
In addition to thickness, temper, surface condition, and finish, aluminum alloy selection is one of the most important factors when specifying foil.
1xxx series, including 1235, 1050, and 1060, are commonly used for general-purpose foil, household foil, packaging, and applications requiring high aluminum purity and good formability.
8xxx series, particularly 8011 and 8079, are widely used for food packaging, pharmaceutical foil, lidding foil, household foil, and other applications requiring a combination of strength, formability, and suitable processing characteristics.
3xxx series, such as 3003, provides higher strength than many 1xxx-series alloys and is used in applications including heat-exchanger fin stock and selected battery or forming applications.
The specific alloy should be selected according to the final application rather than simply by product name. For example, pharmaceutical foil, household foil, battery foil, heat-exchanger fin stock, and lidding foil can require significantly different mechanical properties, surface cleanliness, pinhole performance, and temper conditions.
When placing an aluminum foil purchase order, buyers should specify alloy, temper, thickness, width, coil weight, surface condition, finish, pinhole requirements, oil-residue requirements, dimensional tolerances, and applicable standard. Standards such as GB/T 3198, ASTM B479, or the relevant EN specification should be referenced according to the destination market and application.
