Glass bottles leave the filling line in one of four secondary packs: a shipping carton, a shrink-wrapped tray, a display or shelf-ready box, or a divider set unitised with stretch film. The sales channel picks the candidates, the run length decides whether a formed pack is worth its tooling, and the filling line and pallet decide what can physically be run. Whichever form survives those three tests, its case footprint has to be fixed together with the pallet format, because a case that does not divide the pallet evenly wastes deck space on every shipment.
What each packaging layer is responsible for
Most damaged shipments and unbookable pallets trace back to one layer being asked to do another layer's work. There are three layers, and they are settled in sequence.
- Primary pack. The bottle, its closure and its label. It holds the product, carries the statutory and consumer information, and is the one layer the filling plant controls directly. It is not built to absorb case impacts or carry a stack.
- Secondary pack. The unit that groups bottles. It keeps glass off glass, gives the group a shape a machine can handle and a person can lift, carries the case-level code and, where the channel asks for it, presents the product on shelf. The case format is fixed at this layer, and the case packer tooling, the layer pattern and the pallet count all follow from it.
- Tertiary pack. The pallet with its layer pads, stretch wrap or banding, edge boards and top cap. It turns a stack of cases into a single load for forklift handling and a sea voyage.
Three substitutions cause most of the trouble. A thin carton does not replace a divider, so bottles inside it still knock together and the supplier gets blamed for breakage the pack design produced. Stretch film does not replace a layer pad, and two tiers of glass separated only by film arrive with scuffed shoulders. A display box is not a compression member, however sturdy it looks on a shelf, and its corners crush when it sits under a heavy pallet load in a distribution centre.
The scope here ends at the packed unit and the pallet it stands on. Bracing and positioning that pallet inside a container is a later step, and so is approving the stacking pattern. The decisions made at this stage are written down in the packing specification for the bottle order.
Choosing the form by channel, run length and equipment
The four forms are four ways of operating, not one product at four cost levels. Ask the following in order and usually only one or two remain.
Channel
The channel defines what the outer pack must be before anyone asks what it costs.
- Retail through a distribution centre. The case has to scan, stack and open neatly on the shop floor. That means a carton or a shelf-ready display box.
- Direct to consumer by parcel. Each shipment is dropped and sorted on its own, so it needs a shipper carton with cushioning, either around the retail pack or designed as the secondary pack itself.
- Bulk supply to a filler, co-packer or refill operation. The pack is a handling unit and only has to protect and count.
- Cash-and-carry and food service wholesale. These sit in between and tend to favour a tray that splits into saleable part-quantities without display print.
Run length and order pattern
A formed and glued carton or a formed tray needs a tooling set and a machine set-up, which a long run of a single format recovers. A short run, a mixed order, or a launch whose pack may change next quarter will not recover it. Those jobs are better served by a standard carton size with applied labels, or by a hand-assembled divider set closed in film that needs almost no tooling. The break point is the run length at which set-up is recovered for your real order pattern, not an annual volume read from a catalogue.
Filling line and pallet
Not every plant runs a carton former, a tray former and a shrink tunnel. A form the installed equipment cannot produce becomes either manual work or a new machine. Ask the line which forms it can run at the required rate and which box formats its case packer can form and close; the case packing guide for glass bottles covers that machine in detail. Then ask the pallet whether the resulting footprint divides its deck without overhang.
Carton, tray, display box and divided film pack compared
Use the table to compare, then confirm the choice against a pack drawing and a physical sample for your own bottle and route.
| Form | Typical construction | What it does well | Where it fits | What not to expect from it |
|---|---|---|---|---|
| Shipping carton | Regular slotted carton, or a die-cut carton with a full or partial lid, normally with a divider set wherever glass would touch glass | Shields a fixed count of bottles from handling, carries the case code, and gives flat top and bottom faces so pallet stacking is predictable | Long runs of a stable case format; industrial and wholesale channels; routes where cases stack several high | Bottle separation. With no divider, the bottles touch inside the box and the printed panel is the only barrier |
| Shrink-wrapped tray | Shallow corrugated or solid board tray with a lip, closed over the top with shrink film, sometimes under a printed wrap-around sleeve | Makes one rigid, flat-based unit from a single layer or low stack, so the pallet builds from regular blocks and a whole layer moves as one | High volume of one bottle format; plants with a tray former and shrink tunnel; routes where tray layers stack as a block | Display duty, or compression strength like a closed carton. Film stops bottles falling out; it does not carry a stack |
| Display or shelf-ready box | Die-cut carton with a tear strip or perforated front, printed outside and plain inside, sometimes with a built-in divider | Carries the brand at point of sale, shows the front label, lets staff face up the product without unpacking, and bears the case code until opened | Printed retail programmes; gift and higher-end channels; launches where the pack is part of the marketing | Travelling bare through a parcel network, or stacking under load without a compression check. The opening feature removes stiffness |
| Dividers with stretch film | Corrugated partition or moulded insert seated in a tray or shallow cap, closed with stretch film or banding | Puts each bottle in its own cell so none touch, holds the cells together, and leaves the glass visible for inspection | Short runs and mixed orders; tall or thin-walled bottles; products where one chipped bottle or scuffed label is unacceptable | Stacking by default. With no board top, the film takes the contact from the layer above and creeps under sustained load |
Read across the rows and each form turns out to solve a different problem. The carton deals with handling and stacking, the tray with unitisation and handling speed, the display box with presentation, and the divider set with contact between bottles. When two of those problems are live together, combine forms, for example a divider set inside a carton, instead of hunting for a fifth option.
Film and board are also not substitutes for each other. A shrink tray gives a flat, regular pallet layer with little material, yet leaves bottles touching. A carton separates bottles and takes print, but weighs more and uses more cube for the same count. A divided unit separates with the least board and then depends on film and pallet to hold it together.
How each form fails
- Carton: corners give way when it is stacked damp or too high.
- Tray: film tension set for line speed rather than stability lets the layer walk inside the wrap.
- Display box: the tear line concentrates the compression load and fails first.
- Divided unit: a cell sized to the bottle body, not its widest point, puts the contact on the shoulder.
On the tertiary side, do not count on the pallet wrap to rescue an unstable case. Film will hold a poorly built stack together and then let all of it slide as one block. The pad and top-cap requirement for an export pallet is set by the secondary pack underneath it, not by habit.
Fix the case format and pallet format as one set
Case and pallet are a single decision for reasons of arithmetic. A footprint that does not divide the pallet deck evenly leaves an empty strip along one or two edges, and you pay for that strip in every container for as long as the order runs. It also forces a partial row, which is the weakest feature any load can have.
Start from the pallet. Common export pallets fall in the 1200 by 1000 mm and 1200 by 800 mm families, whose dimensions belong to the ISO 3394 family of transport package sizes. A case occupying about a quarter, a sixth, an eighth or a tenth of the deck divides it cleanly. A footprint chosen because it suits the carton supplier may not.
Then work from the case upward. Case height times the number of tiers, plus the pallet deck and any top cap, must clear the container door opening, and the finished load must stay within the gross weight the forklift and the container payload permit. A case that looks efficient on shelf but is slightly too tall to allow one more tier will cost more in freight than the carton ever saved; in a 40HQ a few millimetres can decide it.
Machinery ties the formats down further. A case packer is built for a range: minimum and maximum footprint, a height range, and a board thickness it can form and close. A palletiser sets its guides and head tooling to the case footprint. Change the case and you change packer tooling, palletiser guides and layer pattern, and possibly pallet height. Switch pallet standard from 1200 by 1000 mm to 1200 by 800 mm and the case layout is invalid even though the product is untouched.
So record case footprint, case height, units per case, tiers per pallet, finished height and pallet format together, and treat a change to one as a change to all. Buyers who settle the case first and the pallet afterwards tend to pay twice: for a tooling change, and then for pallet fill they never get back.
Dividers, inserts and reducers inside the pack
Damage inside a secondary pack has two separate causes. One is glass rubbing on glass under film tension or vibration, which on a decorated or labelled bottle shows as a scuffed label panel or abraded surface. That is a quality claim, not a breakage claim, and harder to settle. The other is a bottle moving in a space too wide for it: it leans on the cell wall, rocks in handling and can fall over when the pack is opened.
| Component | What it controls | When to use it |
|---|---|---|
| Corrugated partition | Removes glass-to-glass contact by giving each bottle a cell; also stiffens the case and raises stack compression strength | The default answer to contact damage |
| Moulded pulp or plastic insert | Separates bottles with a shaped pocket that supports the body or shoulder | Bottles heavy enough to deform a board cell |
| Neck reducer or shoulder clip | Holds the neck so the base cannot swing, which stops tall bottles leaning and toppling | Bottles packed neck up in a shallow tray, where movement is the risk and body contact is not |
How much separation you need depends on bottle and route. Tall, slender, thin-walled or heavily decorated bottles need full cells, since they are the least stiff and have the most to lose from contact. Short, stable, plain bottles in a light pack on a short route often travel in a tray with a simple pad between layers.
Size every cell to the bottle's widest point. A cell that fits the body diameter will pinch the shoulder during loading and can jam the packer.
Separation has a cost beyond material. A divider or moulded insert adds a packing operation and takes a little of the case footprint or height, which lowers the count per pallet. A reducer or clip takes far less but leaves the bottle bodies free to touch. Decide here whether the chosen form needs separation and how much room it may use; the material-by-material choice is covered in our guide to bottle inserts and neck reducers.
Retail requirements for barcodes, stacking and label visibility
A case entering a retail distribution centre is judged against the retailer's own packaging specification, which varies by retailer and market and is the authority. The requirements below appear in nearly all of them.
Scanning and identification
The case needs a case-level barcode derived from the same product identity as the consumer unit, commonly in GTIN-13 or ITF-14 form. It must be printed with adequate contrast and quiet zone on a face that stays readable when the case is stacked and palletised. If a serialised shipping label is required, it goes in a specified area and must not cover the case barcode or the product description. Artwork printed edge to edge with no reserved label area gets the pack rejected at goods-in, whatever the quality of the design.
Where the bottle and the case carry different barcodes, position them so the goods-in scanner can only read the case code. A display box window that exposes the bottle label is a frequent cause of misreads.
Stacking
Expect a stated stacking height and a compression performance checked for warehouse conditions, humid periods included, because board loses stiffness as it absorbs moisture. Retailers may also cap case weight for manual handling and set a maximum pallet stack height below what the case would carry in a dry test.
Label visibility
This is where the secondary pack most often works against the primary pack. A shrink tray band, a divider wall, a display box front or a printed sleeve can hide the label panel, obscure statutory information or rub the label in transit. Close the pack as it will ship and check two things: that everything the contents regulation requires is still readable, and that the brand panel faces the shelf if the channel needs it.
If either fails, turn the bottles so the label faces outward, cut back the printed area of the sleeve, or move the required information onto the secondary pack. The last option means checking the outer pack against the product's labelling rules, not assuming it complies.
Packs for e-commerce parcel dispatch
A parcel is sorted on conveyors, dropped from handling height, sometimes crushed under other parcels and left at a door. No retail case sees that. ISTA publishes test protocols for parcel and packaged-product transport, and a buyer can name one of them as the external standard for the pack. Three design consequences follow.
The secondary pack becomes the shipper. A shelf display box is rarely strong enough alone: its opening feature removes stiffness, and its print cannot take the surface damage parcel handling causes. The usual arrangement is a plain outer shipper carton, the retail pack inside, and cushioning between them, so the outside can take damage that never reaches the product.
Drop protection moves to the inner pack. On a pallet, outer cases spread an impact over many units. A parcel takes it all at one point. Inner separation therefore stops being optional: a divider or insert, a moulded pulp shell, or folded paper or air cushioning that keeps the bottle still in its cavity. A loose bottle accelerates inside the box, stops against the wall and breaks at base or shoulder while the carton stays unmarked.
The parcel has its own limits. Multi-bottle mail order needs a count that stays inside the carrier's weight and dimension limits and is dense enough for the bottles to support each other instead of rattling. Single-bottle orders need a pack designed around one bottle. Returns matter too: a pack that cannot be resealed undamaged will come back in some other container, and the design should state whether that is acceptable. Confirm the performance level with a transit test, not a description.
Compare pack cost per bottle at container level
Material cost per case is the wrong basis for comparing secondary packs. What reaches the buyer's accounts is landed cost per bottle, which moves with three things the case format controls: material and packing cost per case, bottles per case, and how many cases or pallets fit a container.
The chain is simple once formats are fixed. Units per case times cases per layer times layers per pallet gives bottles per pallet. Pallets per container, from the loading plan for the actual pallet and container type, gives bottles per container. Freight per container divided by that figure is freight per bottle. Two cases with identical board cost can land very differently if one divides the pallet cleanly and the other leaves a partial row or loses a tier to height.
Fewer, larger cases are not automatically cheaper. Going from twelve bottles per case to twenty-four halves the cartons and the packing operations, but doubles the case weight, perhaps past the manual handling limit, and alters footprint and height, which alters the layer pattern and possibly the pallet count. Run the comparison at pallet and container level and include breakage, since a bottle lost in a heavier case was already filled, labelled and cased. Our page on reducing glass bottle freight cost without adding breakage works through the freight side of the same sum.
Returnable crates against one-way cartons
A returnable crate with a fixed divider set costs more to buy than a carton, but its cost per trip can drop below the one-way pack when the loop is short, crates are counted and return freight is controlled. It also keeps packaging out of the waste stream, which counts in markets that regulate single-use plastic or packaging waste.
The conditions are demanding: a return route that is really used, a washing step with a defined standard, an account that reconciles losses, and a destination that accepts the crate format. Without them the crate is the dearer option, and a recyclable fibre carton, accepted in most paper streams, carries less risk. Make recycled-content and recyclability claims only as far as the material specification supports them.
What to put in a secondary packaging enquiry
Quotations for secondary packaging can only be compared when every supplier works from the same list. Three items are enough for us to start, and three more turn a first view into a recommendation that can be checked against a pack drawing.
- Channel and route. Retail shelf, e-commerce parcel, wholesale, food service, industrial supply or refill, plus the handling steps: transhipment, floor-loaded or palletised container, any parcel leg. A retailer's packaging specification is worth more than any description, and for parcel routes the intended transit test level changes the design itself.
- Bottle. A drawing or sample with nominal capacity, filled weight, and the widest diameter of both body and shoulder.
- Units per case, or whatever sets it: the channel, a shelf plan, a pallet count or a handling limit.
- Pallet format at both ends of the route, with maximum finished height, maximum gross weight and the container door height.
- Line equipment. The forming, filling, closing and palletising machines the pack must run on, the required rate, and the case packer's format range.
- Volume. Units per shipment and shipments per year, plus the number of pack formats and format changes expected.
Several further points change the answer and should be stated if known:
- whether the tray, carton or box is itself the display unit or transport only;
- print: one-colour flexo, multi-colour, applied label or plain board, and how many artwork versions one run must cover;
- how many cases will be stacked, for how long, and whether storage is humid;
- whether a case barcode, a serialised shipping label or both are needed, and on which face;
- whether the primary label must stay fully visible and legible with the pack closed;
- material constraints such as recycled fibre content, a recyclability claim, plastic reduction, or a returnable crate already circulating at destination.
From that we propose a form, a box format and case height that divide the pallet cleanly, a divider, insert or reducer with the cell size the bottle needs, and the barcode and label-visibility points the outer pack has to respect. Unit cost, order quantity and timing are quoted per project against the actual bottle, print and volume. For how empty glass is bought to begin with, see how glass containers are supplied in bulk.
Questions buyers ask about secondary packaging for glass bottles
How do primary, secondary and tertiary packaging differ for glass bottles?
Primary is the bottle with closure and label. Secondary is the grouping unit, whether carton, shrink tray, display box or divided film pack. Tertiary is the pallet with pads, wrap, cap and banding. They are decided in that order because the bottle limits what can be packed, and the secondary pack sets the footprint the pallet must then accept.
How do I decide between a carton, a shrink tray and a display box?
Begin with the channel, then test the run pattern, then the equipment. Retail distribution needs a carton or shelf-ready box, parcel delivery needs a plain shipper around the retail pack, and bulk or industrial buyers usually prefer a tray. A formed pack only earns back its tooling over a long single-format run, and a form the line cannot run or a footprint that will not divide the pallet is not a real option.
Which bottles need a divider or insert in the case?
Any bottle where contact would lead to a claim: tall, slender, thin-walled or heavily decorated ones, and any product where a scuffed label is unacceptable on an intact bottle. Short, plain, stable bottles on a short route often go without body separation, but check it instead of assuming.
Which comes first, the box format or the pallet format?
Neither. They bind in both directions and bind to the case packer and palletiser as well, so fix pallet format, case footprint, case height, units per case and tiers per pallet together in the packing specification.
What do retailers require of the outer pack?
The details are the retailer's to set. In general terms they ask for a readable case-level code that a shipping label does not cover, a stated stacking height with compression that holds in a humid warehouse, and sometimes a case weight limit for manual handling. Plan the position of the case code and the unit code together.
Can a display box go out as a parcel with no outer carton?
Usually not without a compression and drop check. The tear strip or perforated front that makes it work on shelf weakens it, and printed retail board shows parcel damage. Put it inside a plain shipper with cushioning between, keep the bottle from moving in its cavity, and set the performance level with a transit test protocol such as the published ISTA series.
Does a cheaper case always mean a lower landed cost per bottle?
No. A lower-cost case that divides the pallet badly, or stands a few millimetres too tall and loses a tier, can end up dearer per bottle. Work the numbers through to bottles per container, and value damaged bottles at landed cost, not at the ex-works figure.