Cold-Form Foil vs High-Barrier Film: Choosing the Right Structure for Moisture-Sensitive Tablets

2026-10-29

Why the structure decides stability

For tablets, capsules and softgels, moisture is the most common cause of premature degradation. The blister structure, not the tablet press, sets the moisture barrier the product will see for the next 24 months. Two options cover most projects: cold-form aluminium and high-barrier film.

How the two structures behave

Cold-form aluminium (Alu/Alu) draws a pocket from a laminate of OPA, aluminium foil and a sealing layer. Because the pocket is metal, it behaves as a near-absolute barrier: moisture, oxygen and light ingress are close to zero, and the material does not need drying before forming.

High-barrier film is a thermoformed plastic with a barrier layer, usually PVC/PVDC, PVC/PE/PVDC or a COC-based structure. Barrier performance depends on the polymer combination and gauge, and it degrades with forming depth: the deeper the pocket, the thinner the barrier layer at the corners.

Decision table

Criterion	Cold-form aluminium	High-barrier film
Moisture barrier	Near absolute, independent of pocket depth	Good to very good, sensitive to pocket geometry
Oxygen and light	Fully blocked	Partial, light depends on pigmentation
Tooling	One set of cold-form dies, higher upfront cost	Standard thermoforming tools, lower entry cost
Line compatibility	Requires a cold-form line or combined line	Runs on standard blister lines
Material cost per unit	Higher	Lower to moderate
Recyclability	Aluminium-rich laminate	Polymer-rich, mono-material routes emerging
Best fit	Hydrolysable drugs, effervescents, moisture-critical APIs	Standard solid dosage, high-volume programmes

What to check before deciding

1. Stability data first. Run accelerated and long-term studies in the actual structure. Published water vapour transmission rates are a screening tool, not a substitute for product-specific data. 2. Pocket geometry. Deep or asymmetric pockets erode barrier performance in film structures. If your tablet count forces a deep pocket, cold-form usually wins. 3. Line throughput. Cold-form runs slower per stroke than thermoforming on comparable formats. Confirm the capacity the programme actually needs before committing to tooling. 4. Child resistance and unit-dose. Alu/Alu supports perforated unit-dose and child-resistant formats more easily than most film structures. 5. Sustainability brief. Film structures offer clearer mono-material and recycled-content routes today. If the brand brief requires PVC-free or recycled content, film may win even where cold-form performs better.

How we help you compare

Both structures are produced on the same ISO 15378 certified platform, so the comparison is about your product and line, not about which plant supplies it. Send the dosage form, target shelf life, pocket layout and line type, and our engineers will return a material recommendation with the documentation package needed for your market.

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