Reinforced film for building materials and metals

Building materials and metals are the hardest thing you can ask a stretch film to hold. The mass is high and the footprint is small, so every kilo leans on a short length of film. The surfaces are hard and often smooth — sheet, coated profile, glazed tile — so the wrap cannot bed into the load the way it does around cartons. There is little to grip and plenty that cuts.

Then there is everything that sticks out. Cut ends on tube and bar, band buckles, protruding fixings, splintered timber, swarf on a fabricated part, the corner of the bundle stacked alongside. These loads are also handled more than most: tines in and out, bundle onto bundle, a yard, a truck, a site.

On a pallet of cartons the wrap usually fails slowly: the film creeps, holding drops, the load leans. On a bundle of profiles it fails suddenly. A stretched web is under tension in every direction, so a nick behaves like a crack tip — the film opens along the line of tension and several turns unload at once. The load does not shift a little; it lets go exactly where the film was cut.

The usual response is to move up a micron or two. Toreto measured what that buys, on the same pallet and the same machine, at the same power stretch and tension. Solid film at 23µ held 9.9 kg per square inch using 200 g of film, about €0.48 a pallet. At 17µ it held the same 9.9 with 140 g. Reinforced Supersonic at 16µ held 10 kg per square inch with 66 g, about €0.32. These are Toreto's own tests; cost varies with film price and pallet size.

Going the other way is worse on this kind of load. In the same test, 12µ nano film held least of all, at 7.6 kg per square inch, because it depends on a machine in good order and settings that are exactly right — and a sharp, dense load is precisely where that assumption breaks. Most users end up double-wrapping: 182 g and about €0.64 a pallet, which is 50% slower and 50% more expensive than reinforced film at the same holding.

Supersonic is a reinforced, non-perforated “Tiger” film. The reinforcing is built into the film, so containment comes from structure rather than mass: the web resists the tear that starts at a puncture instead of running from it, and it holds a dense load at a fraction of the film weight. That is the whole argument against buying thickness.

It also changes how you wrap. Built-in reinforcement needs roughly half the revolutions of ordinary film, by hand or by machine, so the wrapper releases pallets about twice as fast. Apply the inside face to the goods, two revolutions at the base, spiral up with a 20–30 mm overlap, two at the top — and on heavy or unstable bundles spiral back down as well, because the criss-cross is what holds a slippery load.

Metal moves between temperatures more than most cargo: warm off a line, cold out of a store into a humid yard, or shipped across two climates. Solid film seals the water vapour in with the goods, and it condenses on the coldest surface it can find — which on a pallet of bright steel is the steel. That is rust, softened cartons and lifted labels on a load that was wrapped correctly.

Where that is the risk, Aerosonic is the perforated version of the same film. Supersonic and Aerosonic are made from the same materials and perform the same, so you can move between them at the same cost per pallet without touching the machine settings. Other breathable films on the market typically cost up to 100% more in use and want settings of their own. Film alone is not a corrosion-protection system, but a wrap that lets the load dry is a very different starting point from one that does not.

Reinforced film unitises a load and protects it. It is not strapping and it does not replace it. Bundles of bar and tube, long timber and tile packs still need banding, corner boards, edge protection and, on a vehicle, proper restraint. Wrap a badly built bundle and you have a badly built bundle in plastic. And no film is a load-securing certification: no roll specification can promise that a load will meet a transport safety standard, because that depends on the load, the vehicle and how it is secured.

Not everything leaving a builders' merchant or a fabrication shop is a cube on a pallet. Toreto also converts narrow-width film for automated wrapping systems and printed or plain polythene bundle wrap — narrow bundling tape, printed to your artwork or plain and pre-stretched for hand use — for profiles, boards and lengths that are bundled rather than palletised. The spec is built around the line and the product rather than picked off a shelf.