Packaging Sampling, Pre-Production Approval and Quality Control

Which types of packaging samples are there?

There are four main sample types, and each answers a different question: stock samples show material and construction, white (structural) samples prove size and fit, digital proofs check artwork and layout, and printed pre-production samples show the finished product before the main run. Ask for the one that answers your current question rather than a "sample" in general.

Stock samples

Stock samples are the quickest way to judge a supplier's workmanship and material options before you commit. Use them to compare paper weights, handle types, cup wall constructions or board grades side by side. They are also useful for food trials: putting your actual burger, fries or soup into a similar construction tells you more than a data sheet.

White and structural samples

For a new size or structure, a white sample checks what drawings cannot: whether the box closes over your tallest burger, whether the bag base takes two meal boxes, whether a lid snaps onto the container. Test with real product, at real temperature, and through the real handling (stacking on a delivery bike, holding at a counter). Structural prototyping for cartons is described in carton dielines, cutting dies and structural prototyping.

Printed pre-production samples

A printed pre-production sample is the closest you get to the finished order without running it. How it is made matters: a digitally printed sample on the correct paper shows design and fit well, but colour can differ from flexo or offset production. If colour is critical, request an ink drawdown or a press proof as well (see Pantone vs CMYK in packaging). For processes with expensive tooling (gravure cylinders, cutting dies), a full production-equipment sample usually means the tooling has been made, which has cost and timing implications; the packaging lead times guide explains how sampling fits into the schedule.

What should a pre-production approval document contain?

Approval should be a written, signed record of exactly what production must match: the specification, the approved proof version and the approved physical sample, along with the agreed tolerances and inspection method. A message saying "looks good" is not an approval document.

A practical approval pack contains:

• Specification sheet: product type, dimensions with tolerances, material grade and gsm, coatings or linings, print process, colours (with references), finishes, packing method (units per sleeve, per case, cases per pallet), labelling of cases.
• Approved artwork proof: version number and date (see packaging artwork preparation).
• Approved sample(s): identified with a reference number, date and signatures of both parties.
• Colour standard: reference sample and, where agreed, measured target values and tolerance.
• Functional requirements and test methods: for example handle load, grease resistance, leak test, lid fit.
• Inspection terms: who inspects, when, how many units (AQL level), and how defects are classified.
• Documentation required with delivery: for example declaration of compliance for food contact, certificates of analysis or test reports where agreed.

What is a golden sample?

A golden sample (also called master sample or reference sample) is the approved, signed physical sample that production and inspections are measured against. It should exist in at least two sets: one kept by the buyer and one by the manufacturer, ideally a third for an inspection agency.

Rules that keep a golden sample useful:

• Sign and date it, with the specification and proof version written on it or attached.
• Store it flat, dry and away from light; printed colours fade and paper ages.
• Replace it when the specification or artwork changes, and mark superseded samples clearly as void.
• Keep a sample from each approved production lot as well; over time these show whether drift is happening.

Which checks happen during production?

In-process control means checking the product while it is being made, not just at the end. Typical checks include first-off approval at the start of each run, then periodic checks on colour, register, dimensions, cutting and creasing, gluing or sealing, and functional properties at agreed intervals.

For food-contact packaging, the GMP Regulation (EC) 2023/2006 requires manufacturers in the EU supply chain to operate a quality assurance and control system, including documentation, and specifically requires that printing inks on the non-food side do not transfer to the food-contact side. The documentation side is covered in food-contact packaging compliance in the EU, UK and US.

How does AQL sampling work for packaging inspection?

AQL (acceptance quality limit) sampling, based on ISO 2859-1, inspects a statistically defined random sample from a lot instead of every unit. The lot size and inspection level give a sample size; the agreed AQL for each defect class gives the maximum number of defective units allowed in that sample before the lot is rejected.

Steps in practice:

• Lot size: the number of units in the shipment or production lot.
• Inspection level: general levels I, II and III, with II the usual default; level III takes larger samples and level I smaller. Special levels S-1 to S-4 use very small samples and suit destructive or expensive tests such as burst or leak tests.
• Code letter and sample size: the standard's tables convert lot size and level into a code letter and a sample size. For example, a lot of 50,000 units at general level II gives code letter N and a sample of 500 units.
• AQL per defect class: an acceptance number (Ac) and rejection number (Re) are read from the table. Continuing the example, at AQL 2.5 the lot is accepted with up to 21 defective units and rejected at 22; at AQL 1.0 the limit is 10 accepted, 11 rejected. Always use the current edition of the standard for the actual figures.

Defect classification is agreed per product:

AQL values above are common practice in consumer goods, not rules; agree them in the approval pack. AQL accepts that some defects will exist in an accepted lot, so a defect that is unacceptable in any quantity should be classified as critical, not left to a percentage.

Typical defects by packaging type

Every product has its own failure modes. Use the lists below to build your defect classification and inspection checklist; your supplier will add process-specific items.

Function tests worth agreeing in advance: handle load and drop tests for bags; hot-water or coloured-liquid leak tests for cups and containers; KIT or practical grease tests for wraps and food bags (see KIT test and grease resistance ratings); compression or edge crush tests for corrugated; barcode verification for retail items. For sensory issues, odour and taint testing of food-contact packaging is often done with methods such as EN 1230; ask whether it applies to your product.

Should you use third-party inspection?

Third-party inspection makes sense for first orders with a new supplier, high-value or high-risk shipments, chains rolling out packaging to many locations, and situations where you cannot visit the factory. An independent inspector checks the lot against your approval pack before shipment and reports with photos and measurements.

Common inspection types:

• Pre-production inspection: confirms materials and set-up before the run.
• During production inspection: checks early output, useful for long runs.
• Pre-shipment inspection: the most common; random AQL sampling of finished, packed goods, usually when at least 80 % of the order is packed.
• Container loading check: counts, pallet condition and loading.

Give the inspector your golden sample, specification and defect classification; without them they can only check general workmanship. The buyer usually books and pays for third-party inspection, and the cost is small relative to the risk of a rejected container at destination. Supplier audits, which assess the factory's systems rather than one lot, are covered in how to choose a custom packaging manufacturer.

Retained samples and traceability

Retained samples (Rückstellmuster in German quality systems) are units kept from each production lot for a defined period, so that any later complaint can be checked against what was actually produced. Combined with lot codes on cases, they make problems traceable.

• Mark every outer case with the order and lot or production date code.
• Keep retained samples from each lot at the manufacturer and, ideally, a few units at your own site.
• Keep them for at least the expected time the packaging will be stored and used, plus a margin.
• Regulation (EC) 1935/2004 Article 17 requires traceability of food-contact materials at all stages, so lot identification also supports compliance in the EU.

How should packaging complaints be handled?

A complaint is resolved fastest when it arrives with evidence: lot code, quantity affected, clear photos or videos, sample units sent back, and a description of when and how the defect appeared. The supplier then investigates against retained samples and production records and proposes corrective action.

A workable complaint process (Reklamation in German procurement) follows these steps:

• Report quickly, quarantining affected stock rather than continuing to use it.
• Provide lot codes, quantities, photos, physical samples and the use conditions.
• Supplier compares with retained samples and the golden sample, and checks production records.
• Agreement on classification (critical, major, minor) using the terms in the approval pack.
• Containment: sorting, replacement or credit as agreed.
• Root cause and corrective action (often called CAPA): what changed and how it will be prevented on the next lot.
• Verification on the next delivery.

Many complaints turn out to be storage or use issues rather than production defects: paper bags stored in damp areas, cups stacked under heavy loads, wraps kept next to ovens. Including storage conditions in the specification (dry, away from heat and direct sunlight, pallets not double-stacked unless designed for it) prevents disputes.

Quality control checklist for your next order

Before you place an order, make sure the following are agreed and written down:

• Sample route: which sample types you need, in which order, and who pays for them.
• Specification sheet with tolerances, signed by both sides.
• Approved artwork proof version and colour standard.
• Golden samples: number of sets, who holds them, storage.
• Defect classification (critical, major, minor) per product, with examples.
• Inspection method: AQL level, AQL values per class, in-house or third-party, timing.
• Function tests and acceptance criteria.
• Case labelling with lot codes; retained sample policy.
• Complaint procedure, response time and evidence required.
• Documents to accompany each delivery, including food-contact declarations where applicable.

Quality expectations are part of the specification, so include them in your enquiry from the start; the packaging RFQ guide shows where they fit. For chains with many locations, packaging for restaurant chains and franchises covers keeping quality consistent across sites and reorders. Product-level quality points are described on each hub, for example custom printed paper cups, custom printed takeaway bags, custom printed burger boxes and custom printed pizza boxes.

9 Packaging is an Istanbul-based B2B manufacturer and exporter of printed packaging, with experience supplying fast-food and chain-style foodservice operators. Sampling steps, approval documents and inspection terms are agreed at quotation and technical review; send your specification and requirements through our contact page.

Related reading

• How Custom Printed Packaging Is Made: Production Process Guide
• Packaging Testing, Quality and Defects Glossary