Soap wrapper sustainability trade-off
A small soap company sells 5,000 bars a month and wants a new 100 g bar wrapper. The current wrapper is a laminated paper/PE structure that cannot be separated and is not accepted by kerbside recycling. The company is considering four options: (1) virgin PET film, 0.04 mm; (2) recycled PET film, 0.04 mm; (3) uncoated paperboard carton with a printed water-based varnish; (4) aluminium foil laminate. The soap contains 8% coconut oil and has a 12-month shelf life. The wrapper must resist oil migration, keep the bar dry, and carry a 70 mm × 40 mm printed label area. The company's factory is 30 km from the soap plant, and the board has a carbon footprint target. A customer survey shows 62% prefer 'plastic-free' packaging, but 28% say they would not buy a carton if the soap dries out. The factory's filling line can handle film on a roll but not pre-erected cartons without a new £12,000 cartoner.
1. Recommend a packaging material or structure, balancing functional requirements, environmental impact and production constraints. Justify your recommendation.
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Recommendation: recycled PET film, 0.04 mm, with a paper label and water-based ink. Reasons:
- Function: PET has good oil and moisture barrier at 0.04 mm, so it meets the 12-month shelf life and prevents oil migration. Uncoated paperboard alone is poor for coconut oil; it will wick oil and stain, and a water-based varnish is unlikely to provide a sufficient grease barrier. A coated or lined carton would be needed, which complicates recyclability.
- Production: The existing filling line handles film on a roll. A carton needs a £12,000 cartoner and pre-erected cartons, which is a major change for 5,000 bars a month.
- Environment: Recycled PET has a lower carbon footprint than virgin PET and is widely collected in bottle streams, though film recycling is less available. It is still plastic, so it does not satisfy the 62% 'plastic-free' preference. Aluminium laminate is high-barrier but usually not recyclable and has high embodied energy.
- Risk: The 28% who would not buy a carton if the soap dries out is a real functional risk; a failed carton could lose more customers than the plastic-free claim gains.
A paperboard carton could be a future option with a greaseproof liner, but it should be piloted, not imposed. The company should label the rPET pack with clear recycling guidance and avoid overclaiming.
2. The company plans to print 'sustainable packaging' on the new wrapper. Explain why this claim could be challenged and what evidence the company would need to support it.
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The claim 'sustainable' can be challenged because it is vague and may focus on one issue (recyclability) while ignoring others: fossil-fuel feedstock for PET, carbon emissions from film production, low actual recycling rates for flexible film, oil migration, and the energy used in the filling line. A pack that is technically recyclable but not collected locally is not circular. The company would need:
- A life-cycle assessment or carbon footprint for each option, including transport (30 km), material production and end-of-life.
- Evidence of recyclability in the actual market, e.g. kerbside acceptance or a take-back scheme.
- Barrier testing (oil migration, moisture) over 12 months.
- Chain of custody for recycled content.
- Customer research on whether the pack actually changes purchasing.
Without this, 'sustainable' is a marketing claim and could be greenwashing. A more defensible claim would be specific, e.g. 'made with 30% recycled PET; check local recycling'.
3. Evaluate the £12,000 cartoner investment against the customer survey data. Show how you would decide whether to invest.
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Cost: £12,000 / 5,000 bars = £2.40 per bar if recovered in one month, £0.20 per bar over 12 months, £0.10 per bar over 24 months. The cartoner also needs floor space, maintenance, and pre-erected carton storage. If the carton adds, say, 5p per unit, the total extra is 15p per bar in year 1, falling later.
Survey: 62% prefer plastic-free, but preference does not equal purchase. The 28% who would not buy a dried-out bar is a functional risk. The relevant question is the incremental sales from the carton versus the cost and the risk. A small trial of 500 bars in two shops would test actual sales and complaints. If the trial shows a sales lift greater than the cost per bar, invest; if not, keep the rPET film and improve its recyclability. The decision should not be made on the 62% headline alone. Also, the carton may not be plastic-free if it needs a greaseproof liner or window, so the survey result may be based on a false premise.