The Functional Basis of Foil in Packaging
Packaging foil works because aluminum is impermeable and reflective. A continuous foil layer blocks light completely, keeps water vapour and oxygen out and retains aroma, which is why the material is used wherever a product is sensitive to moisture, odour or light. Pharmaceutical packaging in particular has to meet moisture proof, mildew proof, freeze resistant, heat resistant and light proof requirements, and a foil barrier satisfies all of them at a thickness measured in microns.
Pharmaceutical Packaging Specifications
Foil for pharmaceutical use is normally applied as the inner layer in direct contact with the medicine, in a laminate that combines the barrier of the foil with the sealability and printability of polymer films.
| Parameter | Common value |
|---|---|
| Alloy and temper | 8011-H18, 8021-O |
| Typical thickness | 0.02 to 0.075 mm |
| Processing method | Compounding, coating, printing |
| End use | Capsules, tablets and granules after compounding and printing |
| Typical delivery form | Rolls with controlled flatness and core size |
8011-H18 is a strain hardened temper used where stiffness and formability on high speed converting lines are needed, while 8021-O is a soft temper chosen for deep drawing and for laminates that must conform to a blister cavity without cracking.
Cigarette and Tobacco Inner Liner
The metallic paper inside a cigarette box is aluminum foil laminated to a paper backing. The family includes gold and silver foil, embossed foil backing paper, printed foil and coloured foil. The two functions that matter most are aroma retention and mildew prevention, because the moisture content of the tobacco must stay stable while the pack is in the distribution chain and on the shelf.
Gold and silver grades for premium branding.
Embossed grades where the backing paper carries a pattern.
Printed and coloured grades for brand specific designs.
Food and Household Applications
Wrapping for cooked food, braised products, soy products, confectionery and chocolate.
Lidding for dairy cups and trays.
Household kitchen foil for storage, grilling and baking.
Laminated pouches for coffee, tea, dried fruit and powdered drinks.
Processing Requirements and Supply Control
Thickness tolerance and flatness are controlled so the foil runs without wrinkling at line speed.
Surface is oil free and free of pinholes, because a pinhole destroys the barrier locally.
Lamination and coating bonds are verified by peel strength tests after curing.
Food contact grades are supplied with the composition and migration documentation required by the destination market.
Rolls are wound on the agreed core with a defined maximum diameter and splice count.
Quality Control and Common Misconceptions
Incoming inspection covers thickness, width, pinhole count and surface cleanliness, and finished laminates are checked for peel strength, print registration and seal integrity. A common misconception is that any foil can be substituted between applications: pharmaceutical laminates need a defined pinhole level and documented material compliance, while a household roll tolerates a much wider range. Treating the two as interchangeable is the most frequent source of rejected packaging.
Frequently Asked Questions
Q: What is the difference between 8011-H18 and 8021-O foil?
A: 8011-H18 is strain hardened for stiffness and converting speed, while 8021-O is annealed and soft so it can be deep drawn or laminated to conform to tight shapes.
Q: What thickness is used for pharmaceutical packaging?
A: Typically between 0.02 and 0.075 mm, depending on whether the foil is used as a blister lidding or as the inner barrier of a sachet laminate.
Q: Why is foil used inside cigarette packs?
A: It retains aroma and prevents mildew by keeping the moisture content of the tobacco stable, while its printability supports the brand design on the inner liner.
Q: Which side of a laminated foil faces the product?
A: The product side is the food contact layer of the laminate, which may be the polymer sealing film, and the composition must comply with the food contact rules of the destination market.
Q: Can aluminium foil be used in a microwave oven?
A: No. Metal in a microwave causes arcing that can damage the appliance or start a fire, and packaging must state this clearly.
Q: What causes pinholes in thin foil?
A: Roll surface defects, inclusions in the metal, or rough handling during rolling and slitting. Pinhole count is therefore specified as a delivery condition.
