Home › Field notes › Pallet Pattern and Container Stuffing for Bagged Goods: Stacking Geome

Modular Bag Pro · 2026-10-11 · 3,496 words · 16 min read

A pallet pattern is the stacking geometry that turns loose cartons into a unit load that stays square under wrap, and container stuffing is the order in which those unit loads or loose cartons are placed so the container can be unloaded in the sequence the destination expects. Programmes start at 500 units per reference, samples take 6-10 working days, bulk takes 35-50 days, release inspection runs to AQL 2.5 and prices are quoted FOB Xiamen. This applies to civilian bagged goods shipped as general cargo; it does not set out any rule for regulated or hazardous consignments, and axle and road limits are set by the countries the load passes through rather than by the pattern.

What a Pallet Pattern Has to Achieve Before the Wrap Goes On

A pattern is chosen to do four things at once: fill the pallet footprint without overhang, build vertical faces that stay upright once the wrap is on, spread load down through the lower layers rather than concentrating it on a few cartons, and leave the top face flat enough to carry another pallet if the load is double-stacked. A pattern that achieves three of those four has usually failed the one it missed.

The most common failure is not collapse but lean. A unit load that is square at the end of the packing bench and leaning by the time it reaches the container has been built with a pattern that left unsupported vertical seams, and wrap cannot pull a leaning stack upright once the lean has started. Lean is progressive: a small departure from square increases the load on the low side, which increases the lean, and by the time the pallet is moved the departure is visible from across the yard.

Sea transit runs 25-35 days and a container is lifted, braked, and set down repeatedly in that window. A pattern that depends on friction between cartons rather than on interlocking loses that friction once the wrap relaxes, which it does as film creeps under sustained tension. That is why a pattern is judged partly on how stable it is before any wrap is applied: if the stack needs film to stand up, it is the wrong pattern for a three-week voyage.

Cube is the other half of the decision. A pattern that interlocks well but leaves a chimney of unused space down the middle of the pallet is paying freight for air, and on a full container that air is measured in cartons that did not ship. The pattern has to be chosen against the actual carton dimensions rather than against a nominal size, because a carton that is a few millimetres out changes which combinations fit the footprint exactly; the packed carton sizes used across the current product range are the ones the pattern is calculated against.

Spec rule: Choose a pattern that stands square without film, that leaves no overhang beyond the pallet edge, and that fills the footprint to within a few millimetres, because wrap adds containment to a stable stack and cannot rescue a leaning one over a 25-35 day sea leg.

Four Stacking Patterns Compared: Block, Brick, Column and Pinwheel

Four patterns cover nearly all bagged-goods pallets. Block, also called aligned, stacks each layer identically with cartons in the same orientation. Brick, or interlocked, rotates alternate layers so the cartons tie across each other. Column stacks each carton directly on the one below with no tie at all. Pinwheel arranges cartons in a rotating square that leaves a small central gap, used where carton length and width combine to fill a footprint that no aligned layout will fill.

Block is the fastest to build and gives the best vertical load path, because every carton is supported along its full length by the carton beneath it. Its weakness is that vertical seams line up from bottom to top, so the stack depends heavily on film and on the friction of the board surface. Brick gives the greatest stability without wrap, because each layer ties the one below, at the cost of build speed and of a load path that crosses carton joints rather than following them.

Column stacking looks attractive because it gives a perfect vertical load path, and it is the right answer for cartons that are genuinely rigid and are strapped rather than wrapped. For a corrugated carton holding a soft article it is usually the wrong answer, because nothing prevents the stack from racking into a parallelogram once the load shifts sideways.

Pinwheel solves a geometry problem rather than a stability problem. Where carton length and width do not combine into the pallet footprint in any aligned layout, rotating cartons around a centre fills the footprint exactly; the penalty is that the central void and the corner-to-corner contacts have to be managed, and the pattern is slower to build than anything else on the list.

Verdict: Use brick interlocking where cartons are matched to the footprint and the load will travel 25-35 days by sea, use block where cartons are stiff and the load is strapped, and reserve pinwheel for footprint ratios that no aligned layout can fill.

Interlayer Sheets, Edge Protection and the Wrap Specification

Three components turn a stack into a unit load: a sheet between layers, protection at the vertical edges, and film around the whole. Each has a distinct job and each is specified as a dimension and a quantity rather than as a description, because a bench that is told to "use corner board" will use whatever is nearest.

Interlayer sheets do two jobs at once. They spread the load of the layer above across the whole face of the layer below, which matters most in brick patterns where carton joints meet, and they increase the friction between layers, which is what resists sliding under braking. A sheet every second or third layer is usually enough; a sheet on every layer adds cost and height without adding stability.

Wrap is specified in four figures: film gauge, number of layers, overlap between turns, and applied tension. Film gauge and layer count together set containment force; overlap sets whether the film behaves as one sheet or as separate bands; tension sets whether the load is held firmly or crushed. Over-tensioning a soft-goods pallet pulls the film into the carton walls and can deform the top layer, which then arrives with visible creases on the outermost cartons.

The wrap has to cover the pallet deck, not only the cartons. A film that stops at the bottom carton leaves the load free to slide off the deck during a lift, and the last two or three turns are what actually tie the load to the pallet. Where a load is strapped as well as wrapped, edge board sits under every strap, because strap force applied directly to a carton corner cuts into it.

Transit performance is verified rather than assumed. Distribution testing sequences published by ISTA exist precisely to expose how a unit load behaves under drops, vibration and compression, and a wrapped pallet that has never been through one is a specification written on optimism rather than on evidence.

Takeaway: Specify wrap as gauge, layer count, overlap and tension, and run the last turns over the pallet deck with edge board under every strap, because film that stops at the bottom carton leaves the load free to slide off during a lift.

Pallet Footprint, Overhang and Height: The Dimensions That Decide Whether a Load Fits

Two footprints dominate export work and the choice is made by the destination rather than by the shipper: the 1200 x 1000 mm pallet that suits most of Europe and the 1200 x 800 mm block pallet, with the 48 x 40 inch footprint normal for North America. A carton dimensioned against the wrong footprint either overhangs, which exposes its corners to damage, or leaves a band of unused deck, which is freight paid for nothing.

Overhang is the defect that costs the most relative to how small it looks. A carton projecting even 20 mm past the deck edge has no support under that strip, so any vertical load on it is carried by board in bending rather than by board in compression, and the corner deforms. In a container, overhanging cartons on adjacent pallets touch each other, and contact between pallets converts independent unit loads into one interacting mass.

Underhang wastes cube in a less visible way. A carton layout that leaves a 100 mm strip of bare deck on two sides means every pallet carries less than it could, and across a full container the shortfall is measured in entire cartons that did not ship. The layout is calculated from the pallet dimensions before the carton dimensions are finalised wherever the programme allows it, which is the reverse of the usual order and is worth doing where volume justifies it.

Height is governed by three different limits that are frequently confused: the door opening of the container, the stacking strength of the lowest carton, and the double-stacking or racking height the destination warehouse can handle. A pallet that is 100 mm too tall for the door cannot be loaded at all; a pallet that is fine for the door can still crush its bottom layer. Container interior volume is usually planned against 20GP ≈28 CBM and 40HQ ≈68 CBM, and the height decision interacts with that plan directly.

Selection rule: Dimension cartons against the destination pallet footprint first and against the container door height second, keeping overhang at zero and bare deck under 100 mm, because a projecting corner deforms under vertical load and a bare strip is freight paid for nothing.

Stuffing Sequence: What Enters First and What Must Come Out Last

Stuffing is an unloading plan read backwards. Whatever has to come out first at the destination goes in last, and whatever the destination can wait for goes in against the bulkhead. Getting this wrong does not damage the goods; it costs labour and time at the far end, and on a tight delivery window that is the same thing as cost.

The physical sequence inside the box follows a fixed logic. Heavy, dense cartons go on the floor and forward; light, bulky cartons go on top and toward the door. Cartons are loaded from the bulkhead toward the door so the loader always has room to work, and each row is brought up level before the next is started rather than building one column to full height and leaving its neighbour low.

Where the container is floor-loaded rather than palletised, the same logic applies at carton level: the first row is placed against the bulkhead, subsequent rows are butted tightly against it, and gaps are filled with dunnage rather than left open. A partly filled row in the middle of a floor load becomes a void that the rows behind it slide into under braking, and the result is a collapsed face at the door when it is opened.

Mixed shipments are where sequence earns its keep. If a container holds two orders for two destinations, or one order split across two distribution centres, the second-unloaded order goes in first and a physical separation is built between them, whether that is a sheet, a marked row or a net. Without a separation, the unloading crew is sorting rather than unloading, and sorting inside a container is slow work in poor light.

Programmes that ship both bulk cartons and individually packed units usually keep the two on separate plans, because the parcel-side packing rules described for modular work backpack ranges shipped direct to end users have nothing in common with a floor-loaded container. Mixing the two inside one container is the fastest way to lose both the cube advantage and the unloading sequence.

The last metre is the one that decides whether the door closes safely. Cartons at the door face have to be restrained, because the door is a flat surface that takes the load of everything behind it once the ship brakes. A restraining net, a strap across the final row, or dunnage filling the residual gap all work, and the choice is written into the stuffing plan rather than left to the loading crew.

Bottom line: Write the stuffing plan as an unloading sequence read backwards, with heavy cartons low and forward, each row brought up level before the next starts, and the door row restrained, because the fallback is sorting inside the container instead of unloading it.

Centre of Gravity, Axle Mass and Why the Heavy Layer Never Rides on Top

A container is lifted by spreader at the corner castings and carried on a chassis with axles, so the position of the mass inside it governs two things outside it: whether the lift is balanced and whether an axle is overloaded. Both are engineering limits rather than preferences, and both are set by the countries the load passes through.

The rule that follows from the lift is that the combined centre of gravity wants to sit near the longitudinal and transverse centre of the box and low. A load built high raises the centre of gravity and makes the box swing under a spreader and roll under braking; a load built with all the mass on one side produces a box that does not sit square on a chassis. Neither condition is visible in a photograph of a full container, which is why the plan is checked on paper before loading starts.

The rule that follows from the axles is that mass has to be distributed along the length rather than concentrated at one end. A dense block of cartons loaded in the forward third overloads the tractor axles even when the total mass is legal, and the same total spread evenly along the floor is well within limit. Road limits differ by jurisdiction and are confirmed with the carrier rather than assumed.

The practical method is to plan by layer rather than by carton. Total mass is divided by the number of layers, dense references are assigned to the lower layers as they are placed, and the plan is checked against declared gross mass before the doors close. Declared mass is the figure the weighing bridge reads, and a discrepancy between declared and measured mass is its own category of problem, separate from anything to do with the pattern.

Judgement: Plan the load by layer with dense references low and mass spread along the length, and check the plan against declared gross mass before the doors close, because a legal total concentrated in one third of the box still overloads an axle.

Why Container Loading Photographs Are Delivery Evidence Rather Than Courtesy

Loading photographs are not a favour to the buyer. They are the only record of the condition of the goods at the moment responsibility transferred, and once a container is sealed nobody can produce better evidence of what was inside or how it was stowed. A claim without photographs is a statement; a claim with photographs indexed to a container number and a seal number is a case.

Six frames cover the whole story. The empty container with its number visible establishes what was loaded into. The first rows against the bulkhead establish the start of the sequence. A mid-load frame with the doors open establishes the pattern and the row build. A frame of the wrapped and labelled pallets before they enter establishes their condition at loading. A frame of the closed doors establishes the seal. A frame of the seal number itself links the whole set to one consignment.

Photographs settle three classes of dispute. Quantity disputes are settled by a frame that shows the row build against a count. Condition disputes are settled by a frame that shows the pallet before it entered the box. Responsibility disputes are settled by the seal frame, because an intact seal with a matching number shifts the burden to whoever opened it.

The set is only useful if it is complete and ordered. A single photograph of a full container proves almost nothing: it shows a wall of cartons and no more. Frames are taken in the order above, stored against the container number, and sent with the dispatch documents rather than held until someone asks for them, because by then the container is three weeks away.

Quality of the goods themselves is documented separately and to a standard: release inspection runs to AQL 2.5 under the sampling scheme set out in ISO 2859-1, and that record covers the product while the photographic set covers the load.

Programme Facts: Unit Loads and the Production Base Behind Them

The SGS-verified production base we work with holds 4,950 m² of floor worked by 137 people across 7 lines with 149 machines, and monthly capacity near 200,000 units; packing instructions there are written as dimensions and quantities rather than as descriptions. A change to a wrap layer count or to interlayer frequency is handled as a specification change and recorded against the reference.

Experience in bag production goes back to 2004 for the founder, with the business started in 2014. A run moves from an approval sample to a counter-signed pre-production piece, into bulk under batch records, then to release against AQL 2.5 before the truck is called. Allow 6-10 working days for a first sample and 12-15 on a complex build, with 35-50 days for bulk.

A Pallet and Stuffing Checklist to Issue Before the Booking

The decisions below all belong to the buyer or to the buyer's nominated forwarder, and all of them have to be settled before the container is booked rather than on loading day. None of them is expensive to make and every one of them is expensive to change once the truck is at the door.

• Confirm the destination pallet footprint and whether the load will be racked, double-stacked or floor-unloaded.
• Set the pattern, and state it on the packing instruction rather than leaving it to the bench.
• Specify wrap as gauge, layer count, overlap and applied tension, with the final turns over the deck.
• State interlayer frequency, edge board dimensions and strap count, with board under every strap.
• Fix pallet height against the door opening, the bottom-carton stacking strength and the destination limit.
• Write the stuffing sequence as an unloading plan read backwards, including any separation between orders.
• Plan mass by layer with dense references low and mass spread along the length.
• Order the six-frame photographic set and require it with the dispatch documents, indexed to the seal.

Money terms run in parallel and leave the engineering untouched: 500 units per reference is the opening gate, settlement is T/T 30/70, and any figure quoted FOB Xiamen is indicative only. Transit differs by mode — sea 25-35 days, air 5-8 days, express 3-5 days — and the mode shifts the packing question rather than removing it, since an air leg is billed on the greater of actual and volumetric mass while a sea leg is billed on cube. A defined pallet presentation is built through custom modular backpack programmes, and packing and inspection options on a live order are listed on the services page.

One clause prevents most arguments of this kind: name in writing who takes the frames, by when they are dispatched, and what follows if the set arrives incomplete. A photographic requirement with no owner is a requirement that quietly goes unmet.