A stretch hood machine pulls a closed tube of film open, lowers it over a stacked pallet of cased glass bottles and lets it contract, so one cold operation both locks the load to the deck and covers its top against rain, dust and container drip. It earns its place on regular despatches that use a repeating pallet format and travel by sea; for small or irregular volumes a spiral wrap is still the proportionate choice, and for dry, short hauls strapping alone can be enough. Judge any method by film weight, energy and container space per pallet shipped, not by the machine or the roll.
Three jobs a securing method has to do
Cartons on a pallet stay in place by friction only. Braking, cornering, crane lifts, weeks of rolling at sea and board that softens as it absorbs moisture all work against that friction, yet the load is supposed to arrive as square as it left the packing hall. Whatever binds the pallet is doing three distinct things, and most methods sell them separately.
- Unitizing. Cartons and layers must not slide against each other or against the deck. Once a top layer has shifted a few centimetres under hard braking, every later movement has room to grow.
- Weather and dust cover. A well-strapped load with an open top lets water in between cartons. The reverse failure also exists: a load fully enclosed in film but not unitized can move as one body inside its own cover.
- Identity and countability. Carton print, the pallet label and handling marks need to stay legible so the receiver can book the pallet into stock without opening and recounting it.
How much each job weighs depends on the shipment. Returnable empties going between two plants on a short domestic leg need unitizing and little more. Filled, labelled product crossing a humid ocean to a retail distribution centre needs all three, sometimes beyond what the carton was designed for. Choosing on the lowest outlay per pallet instead of on the job tends to surface weeks later, as a moisture claim or a load restacked at destination.
Stretch hood, shrink hood, spiral wrap and strapping
The three film methods differ in one respect: film applied cold in a spiral, film applied cold as a closed tube that relaxes onto the load, or film applied loose and then heated. Strapping is the fourth option and encloses nothing.
Stretch hood
The film arrives as a tube sealed across the top, like a bag. The machine stretches it horizontally and vertically, lowers it over the pallet and releases it. Because it recovers in two directions, it squeezes the load inward and presses it down onto the deck, and because the top is closed, weather cover comes with the unitizing instead of as an extra. The conditions are a dedicated machine, a consistent load height and a stable pallet: each hood is made to size and has to pass down over the corners without snagging.
Shrink hood
Often confused with the stretch version, a shrink hood is a loose bag of shrinkable film placed over the load and then run through a gas or electric oven. The film draws onto the profile and sets as a rigid, nearly skin-tight pack, which is very good for keeping water out and keeping the load square. What you pay in is heat: an oven draws a lot of energy, occupies floor space, and needs ventilation and fire safety provisions, and the heat must be kept away from product and labels. It suits loads that truly need a weatherproof skin at a volume that can carry the oven, and is a poor fit for heat-sensitive goods or modest throughput.
Spiral stretch wrap
This is the oldest and most widespread method. Film is tensioned as it is wound up and down the load, and its elastic recovery presses the layers together. A turntable or rotating arm is enough, an irregular load shape is tolerated, and it can be done entirely by hand. Its limits follow from the spiral: the top stays open unless a separate top sheet is added, and the film holds the load in whatever shape it already had instead of pulling it true. Water lying between the wrap and the cartons on an unfixed top sheet is a familiar complaint.
Strapping with corner boards
Vertical bands taken over the load to the pallet, usually with corner boards and a top frame, hold cartons down and square without covering them. Material use is the lowest of the four and inspection is the easiest. It works for a load in a dry container on a short route, and it is a common choice for returnable empties where the cartons are rigid and the thing at risk is the container. It keeps out neither rain nor dust, and it does nothing for a load that already leans.
How the four methods compare
Read the table as a frame for an enquiry, not as a quotation. The last column is qualitative on purpose: the point at which a machine is justified moves with labour rate, energy rate, route and pallet throughput, and has to be worked out for the plant concerned.
| Method | Rain and dust cover | Energy and material | Container fill | Readability of marks | Where it is the sensible choice |
|---|---|---|---|---|---|
| Spiral stretch wrap, optional top sheet | Partial: sides covered, top open unless a sheet is fitted and fixed; water can pool against the cartons | Low: turntable or arm, no heat, modest electrical load; film use climbs fast with the number of turns | Minimal height; a few millimetres at the corners, and the load may sit slightly out of square | Good: transparent overlapping bands leave print and barcodes legible from the side | Any volume, including very small runs; no dedicated machine, hand application possible |
| Stretch hood | Good: closed top over the whole load, held against the pallet so rain runs off | Low to moderate: no heat, but a film carriage, stretching frame and controlled release, with heavier-gauge film than spiral wrap | Small: follows the footprint and adds little height, so fill is largely as with hand wrapping | Fair to good: clear film stays readable; opaque film, used for ultra-violet or light-sensitive contents, needs marks on the hood or a label over it | Regular despatches on a stable pallet format, where hand-wrapping labour has become the constraint and consistent weather cover is valued |
| Shrink hood | Very good: seamless, nearly skin-tight, no open top and no spiral seam | High: the gas or electric oven, plus ventilation, extraction and fire precautions for a heated tunnel | Neutral to slightly positive: thin, tight skin keeps the load compact and square | Fair: clear film is readable, though heat can affect some coatings and printed panels; an opaque bag hides the carton | Higher, repeating volumes of product that needs a weatherproof skin, with enough pallets to carry the oven |
| Strapping, corner boards and top frame | None: every face is open to water and dust | Very low: plastic or steel band, boards and frame, applied by hand or semi-automatic strapper | Negligible to slightly positive: nothing added to the footprint, load can be built to full container height | Best: all print, barcodes and inspection marks visible on every face | Short domestic or dry-container moves of returnable or rigid loads, and as a supplement beneath any film method |
These options combine. The most common industrial arrangement is a hood or film wrap together with a top frame and vertical banding: the film protects and unitizes, and the bands supply the positive downward restraint that film by itself cannot promise.
Load details that settle the choice
No securing method can be proposed sensibly until the load is described, and most of the deciding facts come from the packing design, not from the wrapping equipment. When we review a project we ask for these:
- Pallet format — footprint, deck type and entry. A hood is made to the pallet size, and an overhanging load is hard to wrap well by any method.
- Finished height and layer count. Height fixes the hood length and determines whether a hooding machine can clear the top without a taller gantry.
- Layer pattern. Interlocked cartons forgive loosely applied film far more than a column stack does.
- Single-trip or returnable pallet. A hood wraps the deck too and is cut away on arrival, which alters the routine for a reusable pallet.
- Carton surface and print — coated or not, and whether barcodes and handling marks must show through, which in turn decides whether the film must be transparent.
- Route and season. A humid sea voyage or a monsoon-season despatch raises the value of a closed top over an open spiral.
- Opening at destination — by hand, by knife or with a stretch film remover. The cartons must survive it.
- Carton moisture at wrapping. Film over a damp load seals the moisture in.
- Palletizer line rate. The wrapper takes pallets at the pace they are built, not the pace it would like.
Two of these get forgotten most often. One is the layer pattern: a column stack under a stretch hood can be made very stable, while the same stack under loose strapping will lean, so the method cannot be assessed without the stacking pattern next to it. The other is destination handling. A hood that suits a distribution centre equipped with a film remover is a nuisance at a small plant that opens pallets with a knife and then discards the cut film instead of recycling it.
These inputs are fixed earlier, in the document where buyer and supplier agree carton, pallet and pattern; if that is still open, start with the packing specification for the order before choosing a film.
Condensation, energy and film use
Protection and running expense pull against each other here and are worth assessing separately. Inside a sea container the threat is not rain. It is condensation forming under the roof and dripping onto the top of the load, together with moist air condensing within a loosely wrapped pallet. A closed-top hood answers the first directly, since a drip has no opening to enter, and partly answers the second, because film held tight to the pallet limits air exchange inside the load. Spiral wrap is weakest at exactly this point: the top is open, and many turns of film can hold moisture against the board instead of letting it dry.
Energy is where the two hoods diverge most. A stretch hood uses electricity for the carriage, the stretching and the film handling, with no heating and no oven. A shrink tunnel is a continuous load whether a pallet is in it or not, so it rewards steady, high throughput and punishes stop-start working. At a few pallets a day the oven's idle consumption can outweigh the protection it gives; on a continuous line the balance may reverse. Compare energy per pallet despatched, never the rated power on the nameplate.
Film is easy to misjudge. Hood film is a heavier gauge than spiral wrap, yet it goes on as one piece and replaces many overlapping turns, so thickness is the wrong yardstick. What matters is the total weight applied and wasted. A generously wound wrap can use more film than a hood and leaves more to dispose of at destination. Gauge, the pre-stretch built into the application and the receiver's policy on reusing film all belong in the comparison. Between two suppliers, the one honest figure is film weight per pallet despatched.
Fit with the palletizer upstream and the container downstream
A wrapping station inherits whatever the machines around it deliver. The load's height and squareness are set by the palletizer that stacks the cartons, and no wrapper can straighten a load built out of square; a hood will snag on any carton that sticks out past the footprint. One step further back, the pallet dispenser feeding empty pallets matters as well. A warped pallet, or pallets of varying thickness, give a load that is uneven at the deck, which is among the most common reasons a hood refuses to seat cleanly and ends up being applied by hand at the end of a shift.
Rate is the second inheritance. Each finished pallet must be accepted at the palletizer's cycle time and released before the next one arrives. A hood machine's cycle — stretch, lower, release, return the carriage — is fixed and does not shorten when the palletizer speeds up. Where the two do not match, the usual remedies are a short accumulation of finished pallets between them or a wrapper rated above the palletizer. Accepting a wrapper that is marginally slower and hoping to absorb the gap is the wrong answer, because a wrapper that becomes the bottleneck halts the whole packing line, not only the pallet flow.
Downstream, the wrap determines what the loading team receives, and this is where the securing choice quietly alters freight. A pallet wrapped to its footprint that stays square loads at the planned count. Bulk at the corners, a load left out of square by a thick spiral, or a loose flap on top can take height or width and reduce how many pallets a box accepts. A container is limited by door height and internal width, so a few centimetres repeated on every pallet is a real quantity of freight. Settle it by measuring one wrapped pallet, not by estimating film thickness from a specification sheet. Blocking, bracing and the palletized-versus-floor-loaded decision are covered in our notes on loading glass bottles into a container, and the space an order occupies before a container is chosen is worked through in the CBM calculation guide.
Wood pallets and ISPM 15
Film has no bearing on plant-health rules. Solid wood packaging that travels with the goods, the pallet under a hooded load included, generally falls under the phytosanitary rules most importing countries apply, commonly associated with the ISPM 15 scheme: the wood is heat treated or fumigated and then marked with the approved stamp. A hood neither removes that obligation nor hides the need for a legible mark on the wood that ships. Whether a given pallet satisfies a given destination is a customs question to confirm against that market's current regulation, not to generalise from another market.
What to send with a pallet securing enquiry
A reply that can be compared with another supplier's, instead of a machine description, needs four groups of information in one message.
- The load. Pallet footprint, deck type and entry; carton dimensions and cartons per layer; number of layers and finished height; interlocked or column-stacked; whether any carton protrudes past the pallet.
- The product. Empty or filled bottles, weight of a finished pallet, any light or heat sensitivity, and whether the cartons must be readable through the film.
- The operation. Pallets despatched per shift or per day, the palletizer's cycle time, and the space at the wrapping position including headroom.
- The route and destination. Trade lane, destination port or door address, season of despatch, whether the container is likely to be humid, and how the load is opened on arrival.
From that, a useful answer names the method that fits load and route, the film specification and film weight per pallet, the machine cycle against the palletizer, the floor space and services required, the effect on container fill, and a comparison expressed per pallet despatched. If the volume does not support a machine, the answer should say so and propose hand wrapping or banding instead of an installation.
Nothing on this page states an energy figure, film weight or breakage rate for a particular plant or shipment. Such values remain planning estimates until they are measured on your own pallet, at your own stacking height and on your own route, and that measurement, not a brochure, is what an installation should be accepted against.
Questions buyers ask about stretch hooding
How does a stretch hood differ from a shrink hood?
The stretch hood is a cold process: the tube is opened mechanically, dropped over the pallet and allowed to recover, with no heat at any stage. The shrink hood starts loose and is tightened in an oven. In practice one consumes electricity for drives and the other consumes energy for heating; the shrink version gives the tighter, more seamless cover, but loses its appeal on intermittent throughput because the oven keeps drawing while empty.
Is a hood machine worth having over hand or turntable wrapping?
That turns on labour and consistency more than on protection. Manual and turntable wrapping suit low, irregular volumes, but a person applies them, so the number of turns, the tension and the wrap height drift between pallets and between shifts. A machine runs the same programme every time, which has value when a customer expects uniform loads or when a claim must be defended. Where the machine pays back depends on the local labour rate and pallet throughput and should be calculated for the plant, not taken from a general figure.
At what volume does a hood machine make sense?
No universal number exists. Labour rate, energy and film outlay, and the consistency the customer expects all drive it. As a rough shape: hand or turntable wrapping for low and irregular volumes, a stretch hood once wrapping labour is a constraint and the pallet format repeats, and a shrink hood for steady, high throughput because the oven runs continuously. Compare on the basis of each pallet despatched, using your own labour rate and pallet count.
Does the wrap change how many pallets a container takes?
Usually only a little, though the effect adds up. Hoods and film wraps follow the footprint and add little height, so the count normally holds. Trouble comes from thick spiral film at the corners or a loose top flap that costs height at the door, which is where the count is decided.
Will carton markings still be readable?
Through clear film, yes, as long as the layers are not so numerous that print is obscured and the barcode sits on a face covered by a single thickness instead of an overlap. Under an opaque hood chosen for light-sensitive contents nothing can be read, so either the pallet label goes over the hood or the hood carries the handling marks and barcode. Decide this before ordering hoods, since the film specification follows the requirement.
What pallet and stacking pattern does a hood need?
Stable ones. Pallets must be consistent in dimensions, and no carton may protrude at a corner where it would catch the descending film. Interlocking patterns resist sliding in both directions and help the hood; a column stack leaves the film alone to stop the layers moving. A flat, even deck matters for the same reason given above for warped pallets.