Most people never notice cold seal, and that is the point. It closes a chocolate bar, an ice cream wrapper, a medical dressing, at a speed no heated jaw could match, and it leaves no trace of having been there. Here is how it works and where it belongs.
What cold seal actually is
Cold seal is a water-based latex coating that bonds only to itself. It is a cohesive, not an adhesive in the everyday sense: it has almost no affinity for the product, the operator’s hands, or the reverse face of the film. Bring two coated surfaces together under nip pressure and they join instantly.
Nothing is melted. No thermal energy passes through the substrate at any point in the cycle. That single fact is where every advantage and every constraint below comes from.
Why removing heat changes the whole line
On a heat-sealed pack, the jaws have to push energy through the outer layers to reach the sealant. Everything in the path gets warm, including the product sitting behind it.
For a great many products that is simply unacceptable. Chocolate blooms, the dull grey film that appears when cocoa butter migrates and recrystallises after even mild warming. Ice cream begins to melt at the seam and refreezes with ice crystals. Some pharmaceutical actives degrade. Fresh bakery loses structure. In each case the pack would be fine and the product would not.
Cold seal removes the question entirely. There is no thermal exposure to manage, so there is no thermal damage to design around.
Where the speed actually comes from
Cold seal is often described as faster, which is true but usually explained badly. The gain is not that the seal forms more quickly. It is that three waiting periods disappear:
- No heat-up. The jaws do not need to reach and hold a set point before the line can run.
- No dwell. Heat sealing needs contact time for energy to travel through the film and soften the sealant. Cold seal needs pressure, which is instantaneous.
- No cool-down. A heat seal is at its weakest immediately after the jaws open, while the sealant is still molten. A cold seal is at full strength the moment it is made.
On high-speed horizontal flow wrap this compounds, and it is frequently worth more than the difference in coating price. It also removes the most awkward failure mode in form-fill-seal: a pack loaded before its seam has set.
Substrate integrity, and why it matters most on thin structures
Heat does not only reach the product. It reaches the film. Thin structures distort, shrink slightly, or lose the flatness that registration depends on, and print can scorch if the jaws are pushed hotter to compensate for a slow line.
Because cold seal introduces no heat, the substrate leaves the machine in the state it entered. On thin films, metallised layers and foil laminates, where there is very little material to absorb a thermal excursion, this is often the deciding argument rather than a secondary benefit.
It also matters for the direction the industry is moving in. In a mono-material structure, the layer being sealed and the layer that must not melt are the same polymer, so the comfortable temperature gap is gone. A system that never applies heat is indifferent to that problem.
What cold seal asks for in return
It is not free, and a supplier who presents it as pure upside has not run it.
- Both faces must be coated. Cold seal bonds only to itself, so it has to be applied wherever a seal is required, in register. That is a coating cost and a print-station decision, not just a material choice.
- Untreated faces need a release lacquer. Without one the reel bonds to itself in the roll. This is not an edge case; it is the normal requirement on untreated substrates.
- Storage discipline. The property that makes the coating bond under pressure at ambient temperature is exactly the property that makes it block in a warm warehouse. Coated reels have their own storage conditions and their own shelf life, separate from the drum’s.
- Material cost is usually higher per kilogram than a heat seal lacquer. Whether that matters depends on coat weight and line speed, which is why the comparison has to be made per thousand packs.
Where it earns its place
Cold seal is a specialist system, and it is worth being honest about that. It is the right answer when at least one of these is true:
- Confectionery and snacking. Chocolate, filled bars, delicate baked goods: anything where a warm jaw would mark, soften or bloom the product.
- Frozen and dairy. Ice cream and frozen novelties, where a hermetic seal is needed but the product cannot be allowed to soften at the seam.
- High-speed flow wrap, where throughput is the binding constraint and the dwell time of a heat seal is what is capping the line.
- Thin or heat-sensitive structures, including metallised film and foil laminates that distort under a hot jaw.
- Medical and dressing applications, where a clean peel and no thermal history are both required.
If none of those apply and the product is thermally robust, a heat seal lacquer is usually the simpler and cheaper system. We would rather say so than sell the wrong one.
The rules that apply
Cold seal sits in a different regulatory box from heat seal chemistry, and it is worth knowing which one.
- In the United States, cold seal is governed by 21 CFR 175.125, the section for pressure-sensitive adhesives, rather than the general adhesive section. The distinction exists because these systems bond without the thermal history the other sections assume.
- In the EU, Regulation (EC) No 1935/2004 is the framework and Regulation (EU) No 10/2011 governs plastics, with specific and overall migration limits. A layer that is not in direct food contact may use non-listed substances provided they are not mutagenic, carcinogenic, toxic to reproduction or in nanoform, which is the functional-barrier logic most wrapper structures rely on.
- Regulation (EU) 2025/351 has applied since 16 March 2025 and tightens what the declaration of compliance has to carry. The transitional period for material placed on the market under the previous rules closes on 16 September 2026.
Ask for the technical data sheet, the safety data sheet and a declaration of compliance matched to your structure rather than to the product family.
How to trial it on your line
A cold seal trial answers four questions, and it is worth setting it up to answer all four at once:
- Does it bond at your nip pressure and speed? Send the real film, from current production, with its treatment level.
- Does it block? Coat a reel, store it warm for a realistic period, then unwind it. This is the failure that appears after you have committed, so bring it forward.
- Does the release side hold? On untreated faces, confirm the release lacquer is doing its job across the full reel, not just the first metres.
- Does the seal survive distribution? Drop, vibration and, for frozen, a realistic cold chain.
Send us the substrate, the structure, your line speed and the seal you need, and you will get a grade recommendation with the reasoning attached.
Frequently asked questions
What is cold seal adhesive?
A water-based latex coating that bonds only to itself under pressure, with no heat applied at any point. Two coated surfaces brought together in a nip join instantly. Because it is a cohesive rather than a conventional adhesive, it has almost no affinity for the product or for the uncoated reverse face of the film.
Why is cold seal faster than heat seal?
Not because the bond forms more quickly, but because three waiting periods disappear: no heat-up before the line can run, no dwell time for energy to travel through the film, and no cool-down before the seam can take load. On high-speed horizontal flow wrap this is often worth more than the difference in coating price.
Which products need cold seal rather than heat seal?
Anything that cannot tolerate a warm sealing jaw. Chocolate and filled confectionery, which bloom when cocoa butter migrates after mild warming; ice cream and frozen novelties; some pharmaceutical actives; fresh bakery; and medical dressings. It also suits thin, metallised or foil structures that distort under heat.
Does cold seal require a release lacquer?
On untreated faces, yes. Without one the coated reel bonds to itself in the roll. This is the normal requirement rather than an edge case, and any qualification should include a warm-store blocking check on a coated reel before the grade is designed into a structure.
Which regulations cover cold seal adhesives in food contact?
In the United States cold seal falls under 21 CFR 175.125, the section for pressure-sensitive adhesives, rather than the general adhesive section, because it bonds without thermal history. In the EU, Regulation (EC) 1935/2004 is the framework and Regulation (EU) 10/2011 governs plastics, as amended by (EU) 2025/351 whose transitional period closes on 16 September 2026.