Friday 17 July 2026
Hot-melt vs cold glue is one of the most consequential adhesive choices on a UK packaging line. Hot-melt is faster, more compatible with most board grades, and forgiving at high cartoning speeds. Cold glue, including PVA-based and dextrin-based systems, holds bond strength longer, deals well with porous unprinted board, and tends to score better on certain audit standards. Picking the right one starts with the line, the board and the auditor sat in the same conversation.
Hot-melt is a thermoplastic adhesive applied at 160 to 180 degrees Celsius from a heated tank or cartridge. The polymer system, typically EVA-based or metallocene-based, melts under heat and cools rapidly back to a solid bond on the carton or case. Open time, the window between application and pack closure, sits at one to three seconds for most cartoner-grade hot-melts.
Cold glue is water-based. PVA emulsions dominate in carton and case sealing applications. Dextrin-based systems still appear in some lower-speed lines, particularly for paper-on-paper bonds. Cold glue cures by water absorption into the substrate rather than by cooling. Set times sit at 30 seconds to two minutes, depending on board absorbency and ambient humidity.
Application methods differ. Hot-melt typically applies through a heated nozzle or slot. Cold glue applies through a wheel, brush or low-pressure nozzle. Cleaning, maintenance and changeover routines on the application head differ accordingly.
Speed favours hot-melt. Carton lines running at 200 to 400 packs per minute almost universally use hot-melt because cold glue cannot reach a closure-ready bond inside the compression dwell time of a high-speed cartoner. Most cold-glue cartoners cap out at 120 to 180 packs per minute.
Bond strength tells a different story. Cold glue bonds typically continue strengthening for hours after pack closure, ending at peak strength once moisture has fully migrated. Hot-melt reaches near-peak bond within seconds and stays there. For long shelf life and aggressive transport handling, cold glue often holds bond longer than hot-melt under sustained load.
Heat resistance is the third dimension. Standard hot-melts soften at around 60 to 80 degrees Celsius. Cold glue is unaffected by heat below 100 degrees Celsius. Lines packing into hot supply chains, including export to warm climates, often spec cold glue or specialist high-melt-point hot-melt for that reason.
Hot-melt struggles with three substrates. High-grease packs, including butter and oily ready-meals, see grease migration into the hot-melt bead and bond failure. Frozen packaging applied at sub-zero substrate temperatures cools the bead too quickly and bond strength drops. Highly polished or coated board surfaces give hot-melt limited mechanical key.
Cold glue handles all three of those well, particularly the porous board surfaces typical of unprinted recycled material. The trade-off sits at the high-speed end of the carton range, where cold glue simply cannot cure fast enough.
Lined corrugated cases for transport packaging usually take hot-melt cleanly. Folding-box-board cartoners with high-coverage print sometimes prefer cold glue for the longer bond life on glossy stock.
Hot-melt and cold glue both have food-contact-grade variants. The audit conversation usually centres on indirect food contact, where adhesive is on the outer carton or case rather than touching product. BRCGS certified sites typically accept both adhesive types when supplied with current migration test certificates from the adhesive manufacturer.
Direct food contact applications, including pre-glued sleeves on food trays, are more sensitive. PVA-based cold glue with a confirmed indirect-food-contact certificate is often the simpler audit position. Hot-melt food-grade variants exist and are widely used, but the certification chain runs longer.
Pharmaceutical packaging adds further constraints under EU GMP and similar standards. Adhesive selection there is rarely a free choice and is usually fixed by validation history.
Hot-melt application splits into bulk tank and cartridge systems. Bulk tank holds 5 to 25 litres of melted adhesive. Cost per gram is typically 20 to 40 percent lower than cartridge equivalents. The trade-off is daily cleaning of the tank and feed lines, plus the safety considerations of a hot tank in the production area.
Cartridge systems hold pre-melted adhesive in disposable cartridges. Cost per gram is higher, but cleaning and tank safety drop to near-zero. Cartridge systems suit lines with frequent changeovers, multiple adhesive grades or smaller batch sizes.
Cold glue is almost always supplied in bulk drums or pails feeding a low-pressure pump. The system is mechanically simpler than a hot-melt tank, but the cleaning routine differs. Cold glue residue dries and hardens on equipment if not cleaned regularly.
Hot-melt vs cold glue is rarely a free-choice decision. The line speed, the board, the supply-chain temperature profile and the audit standard all narrow it down quickly. Hot-melt suits high-speed cartoning on dry, non-greasy product. Cold glue suits lower-speed lines, heat-sensitive supply chains, porous board and certain audit positions. Cartridge versus tank choice on hot-melt depends on changeover frequency and operational risk tolerance.
Talk to our engineers if you want to specify or change the adhesive system on your cartoner, sleever or case-packer.
Specify the right adhesive system with our engineers.
Talk to our engineers