Plain
Unprinted, primed foil for generic packs or overprinting on the blister line.
Pharmaceutical blister foil
PTP Aluminium Foil for Blister Packs
PTP (press-through pack) foil is the hard aluminium lidding that seals a pharmaceutical blister and lets the patient push a tablet straight through it. It is usually 8011 or 1235 in H18 temper, 20 – 25 µm thick, primed and printed on the outside and coated with a heat-seal lacquer on the inside. This guide explains the alloys, properties and coating choices, and Metline supplies PTP-grade foil worldwide.
- Alloys
- 8011, 1235, 8079, 1100, 3003
- Tempers
- H18 (hard), O (soft)
- Thickness
- 0.018 – 0.100 mm
- Width
- 200 – 1,500 mm
What PTP foil does in a blister pack
A blister pack has two parts: a thermoformed cavity web in PVC, PVC/PVDC, PET or PP, and a flat lidding foil sealed over it. The lid must keep moisture, oxygen and light away from the drug for the full shelf life, then split cleanly when the tablet is pressed. Hard-temper aluminium foil is one of the few materials that does both.
Aluminium foil above about 17 µm is effectively a complete barrier to water vapour, gases and light, provided it is free of pinholes. In H18 temper it is stiff and has low elongation, so it ruptures under thumb pressure rather than stretching. Soft O-temper foil is used for child-resistant peel-push and peelable lids, where the foil is laminated with paper or PET.
Alloys, tempers and sizes
| Alloy | Temper | Thickness (mm) | Width (mm) | Core ID (mm) | Coil OD (mm) |
|---|---|---|---|---|---|
| 8011, 8011A, 8079 | O, H18 | 0.018 – 0.100 | 200 – 1,500 | 75 / 76.2 | 300 – 600 |
| 1235, 1145, 1100, 1200 | O, H18 | 0.018 – 0.100 | 200 – 1,500 | 150 / 152.4 | 450 – 1,200 |
| 3003, 8006 | O, H18 | 0.018 – 0.100 | 200 – 1,500 | 75 or 150 | To order |
8011 is the standard PTP alloy: its iron and silicon content gives fine grains, good strength and fewer pinholes at thin gauges. 1235 is used where higher purity is preferred; 8079 offers good formability in soft temper. 3003 and 8006 are stronger and appear in some lid and container foil, less often in PTP.
| Characteristic | High-precision grade | Standard grade |
|---|---|---|
| Thickness tolerance (0.018 – 0.100 mm) | ±4 % of t | ±6 % of t |
| Width tolerance, ≤ 800 mm | ±1.0 mm | ±1.0 mm |
| Width tolerance, > 800 mm | ±1.5 mm | ±1.5 mm |
| Joints per roll, OD ≤ 500 mm | Max. 1 (none above 0.050 mm) | Max. 1 |
| Joints per roll, OD > 500 mm | Max. 2, at least 2,000 mm apart | Max. 2 |
Mechanical properties of PTP foil
| Alloy | Temper | Thickness (mm) | Tensile strength (MPa) | Elongation (%) |
|---|---|---|---|---|
| 8011 / 8079 | H18 | 0.018 – 0.100 | ≥ 150 | ≥ 1 |
| 1235 / 1100 / 1200 | H18 | 0.018 – 0.100 | ≥ 135 | — |
| 8006 | H18 | 0.018 – 0.100 | ≥ 180 | ≥ 1 |
| 8011 / 8079 | O | 0.018 – 0.025 | 55 – 105 | ≥ 1 |
| 8011 / 8079 | O | > 0.040 – 0.100 | 60 – 120 | ≥ 8 |
| 1235 | O | > 0.040 – 0.100 | 55 – 110 | ≥ 8 |
Representative specification values; the agreed limits for your order are confirmed on the mill certificate.
For push-through lids the useful property is burst behaviour rather than tensile strength alone. Specify H18 temper and confirm push-through force on the finished pack, since cavity geometry, lacquer weight and seal pattern all change how easily the tablet breaks through.
Pinholes, cleanliness and seal performance
- Pinholes: unavoidable at very thin gauges, they fall sharply as thickness rises. Agree a maximum count per square metre and a maximum diameter, measured on a light table.
- Surface cleanliness: residual rolling oil impairs primer and lacquer adhesion. Plate makers specify a wettability (dyne or water-brush) test.
- Seal strength: the lacquer must bond to the cavity film; a common target is above about 10 N per 15 mm, verified on the customer's blister machine.
- Flatness and winding: tight, even winding without telescoping avoids wrinkles on high-speed lines.
- Food and drug contact: confirm compliance of lacquers and inks with the regulations in your market.
Printing options for PTP foil
Printed
One or two sides; single-colour to multicolour gravure printing, with registered batch-coding windows.
Coloured and gold
Tinted lacquers on one or both sides for brand identity and product differentiation.
Anti-counterfeit
Hidden images, fine-line patterns and positive/negative printing to deter copying.
Tell us whether you need bare H18 foil for your own converting line or coated lidding foil, and the cavity material the heat-seal lacquer must match (PVC, PVDC-coated PVC, PET or PP).
References and standards
- EN 546-1/-2/-3 – Aluminium and aluminium alloys: foil, delivery conditions, mechanical properties, tolerances
- EN 602 – Aluminium and aluminium alloys: wrought products for food contact, chemical composition
- ASTM B479 – Standard Specification for Annealed Aluminum and Aluminum-Alloy Foil for Flexible Barrier Applications
- The Aluminum Association – Aluminum Standards and Data
PTP aluminium (aluminum) blister foil: FAQs
What alloy and thickness is used for PTP blister foil?
Most push-through lids use 8011 or 1235 in H18 hard temper, 20 to 25 µm thick. Hard temper lets the foil break cleanly when the tablet is pressed.
What is the difference between PTP foil and cold-form (Alu-Alu) foil?
PTP foil is the hard, flat lid. Cold-form foil is soft O-temper foil, usually 45 – 60 µm, laminated with nylon and PVC and pressed into cavities to make a fully aluminium blister.
How are pinholes controlled?
By clean casting and rolling and by thicker gauges: pinholes drop sharply above about 20 µm. Buyers set a maximum number and size per square metre in the specification.
Which heat-seal lacquer do I need?
It must match the cavity film. PVC and PVDC-coated PVC are the most common; PET and PP cavities need dedicated lacquers. Coat weight depends on the sealing conditions of your blister machine.
Can PTP foil be supplied in narrow slit widths?
Yes. Foil can be slit to the web width of your blister line, on 76 mm or 152 mm cores, with joint limits per roll agreed in advance.
Need PTP blister foil?
Send the alloy, temper, thickness, width and coating requirement. We reply with specification, certification and a delivered price.
