The brief
A promotional distributor wants five thousand hand warmers for a corporate campaign, split across three shell colours that match the client's brand palette. The distributor has a fixed delivery window, a fixed budget per unit, and one non-negotiable requirement: every carton must be openable at a regional warehouse and repacked into individual kits without the warehouse needing to count colours again. This is a fictional demonstration case created for a coursework assignment; no real brand, buyer or order is described. The numbers below are illustrative and chosen to make the constraints visible, not to describe a real quotation.
The brief looks like a colour problem. It is actually a packing problem, and the packing decision constrains the colour allocation before any shell is moulded.
Colour allocation is a production constraint
Shell colour is an injection moulding variable. Changing colour means a colour change on the machine, a purge, and a minimum run that makes a small colour share expensive per unit. A promotional order that asks for an even three-way split is asking for three runs; an order that asks for a dominant colour with two accents is asking for one long run and two short ones, and the short ones carry most of the cost per unit.
The heating element, the control board, the NTC thermistor, the OTP protector and the battery compartment do not change with colour. That is the useful part of the brief: a colour change is a shell and printing change, and it should not touch the validated build. If a supplier proposes to change the heater or the board for a colour variant, the variant has become a different product and needs its own sample approval.
Decisions and where they lock
| Decision | Constraint it collides with | Where it gets locked |
|---|---|---|
| Three-way even split | Minimum run per colour and purge cost | At the moulding schedule, before pricing |
| Shell colour vs printing colour | Pad printing on a dark shell needs a different ink and a second pass | At artwork approval |
| Number of cartons per colour | Warehouse repacking speed versus carton count | At the packing specification |
| Mixed cartons or single-colour cartons | Inspection sampling and counting at the warehouse | At the purchase order |
| Accessory and cable colour | Accessory lead time is independent of the warmer | At the accessory purchase |
Three ways to pack a mixed order
The packing method decides how the inspection is run, so it has to be chosen before the inspection plan is written.
The first method is single-colour cartons, with the colour marked on the outer carton and on the inner box. The warehouse repacks by opening one carton and taking a fixed quantity, and no counting of mixed contents is needed. The cost is more cartons and more carton labelling, and the benefit is that a colour shortage is visible immediately.
The second is ratio-packed cartons, in which each carton contains a fixed set of colours in the agreed proportion. The warehouse can ship a carton as a kit, which is the fastest option at the far end, but the packing line has to count three colours per carton and the inspection has to verify the ratio rather than a total.
The third is bulk mixed packing, with all colours in one carton and a colour count sheet inside. It is the cheapest to pack and the most expensive to repack, and it is the option most likely to produce a shortage that nobody notices until the last week.
For this brief, ratio packing fits the warehouse requirement and single-colour cartons fit the inspection requirement. The resolution was to ratio-pack the retail cartons inside single-colour master cartons, which satisfies both and adds one labelling step.
Inspection nodes that cannot move
Three inspection points are fixed by the process rather than by preference. The first is the shell colour check at the start of each moulding run, because a colour drift discovered after five hundred units is a scrap decision. The second is the functional check after assembly, on every unit in the sample, covering the heating element, the level control and the charging path; a colour variant that skips this check has skipped the only test that matters.
The third is the carton-level check before sealing, which is where the colour mix is verified against the ratio sheet. That check cannot be moved to the loading dock, because once the carton is sealed and palletised, verifying a ratio means opening cartons again.
Colour also affects the carton marking. A master carton that carries the wrong colour code is a repacking problem at the destination, and the outer package marking rules that apply to battery-containing shipments do not relax because the order is promotional. The outer package marking note is worth reading before the carton artwork is approved, since a marking error found at the freight forwarder is more expensive than one found at the printer.
What this case is not
It is not a price benchmark. The unit economics of a promotional order depend on the colour split, the packing method and the delivery window, and a figure from one brief transfers to another only by coincidence.
It is not a private label rollout either. A single promotional order ends when the cartons ship; a retail private label programme continues through packaging compliance, store listing and repeat production, and it has its own rework points and its own approval chain. Treating a promo order as a small version of a private label programme is how a promo timeline acquires a compliance review it never budgeted for.
And it is not a template for claims. A promotional gift set often carries a warning label demanded by the destination market, and the Prop 65 checklist applies to the printed box whether the order is promotional or retail. Colour variants do not change the warning text, but a new box design does change where it sits.
The allocation sheet that worked
The colour allocation sheet carried one row per colour and the following columns, which is the minimum that survived the first production meeting:
- Colour name, and the reference used by the moulding supplier.
- Quantity per colour, and the percentage of the order.
- Carton configuration, including the ratio per carton.
- Artwork revision for the retail box and the master carton.
- Inspection sample size per colour, not per order.
- Accessory colour and quantity per carton.
- Sign-off name and date for the colour standard.
The last line is the one that prevents the recurring argument about which shade was approved. A physical colour standard signed by both parties is more useful than a photograph, and a photograph taken under a different light proves nothing.
The sequence that held
The order ran in a fixed sequence: colour standards signed, shells moulded per colour, assembly on the validated build with no component change, functional inspection per sample, ratio packing with a carton-level check, then pallet marking and freight booking. The two points where a promotional order usually slips are the colour standard sign-off, because it waits on the client, and the carton artwork, because it waits on the warning text. Both sit early in the sequence for exactly that reason.
Next step
If you are planning a mixed-colour promotional order, bring the colour split and the packing requirement to the first conversation rather than the third, or raise the brief with our team through contact.
Written for the Emberly heating-element programme. Specifications are illustrative; confirm every figure against a supplier test record.