Packaging QC Checklist: What to Inspect, and What to Ask For
Three inspection gates, the checks that run on every lot, what AQL 2.5 does and does not allow, your own inbound checklist, and the records to request when a batch is questioned months later.
Inspection is a three-gate system, and the tests that matter run on the assembled unit
Incoming, in-process and outgoing. Every order passes all three, and the checks run on the actual bottle rather than on a sample of resin.
The purpose of the checklist below is not to audit a supplier. It is to give a buyer enough structure to know what was checked, what the acceptance basis was, and what to do when a lot is questioned after it has already shipped.
This guide is the inspection checklist. The test methods and the acceptance basis behind each line are on packaging testing, and the document system is on quality & compliance.
Three gates, and what each one is for
The gates run in sequence and each one exists because the previous gate cannot catch what the next one catches.
| Gate | When it runs | What it covers | Why it exists |
|---|---|---|---|
| IQC — incoming | On arrival, before anything is moulded. | Resin identity and grade against the specified grade and supplier batch, moisture content measured before drying, and incoming closures and dispensers checked. | A resin or a closure that is wrong at the start cannot be inspected into being right at the end. |
| IPQC — in-process | Continuously, while the line runs. | Hourly patrol checks on weight, wall thickness and neck dimensions, visual defect inspection every 30 minutes, capacity and fill-height spot checks. | A drift is caught while it is still correctable, rather than after a pallet has been built. |
| OQC — outgoing | On the finished lot, before packing is sealed. | AQL 2.5 sampling on the finished batch, leak test on the assembled bottle and closure, drop test on packed units where the route justifies it, and carton count, labelling and shipping marks checked against the packing list. | This is the last gate before the goods become yours, so it is the one that has to be documented. |
The checks that run on every lot
These are not exception checks. They run in process and at final inspection, and the results go into the QC report for the lot.
In-process and outgoing checks
- ☐Visual defect inspection at a 30-minute interval throughout the run.
- ☐Colour and appearance judged against a physical master sample that both sides hold.
- ☐Weight sampled against the approved specification within ±2%.
- ☐Wall thickness at four points per cavity, because a single thin spot at the shoulder is a leak or a drop failure later and will not appear on a finished-goods weigh-in.
- ☐Capacity and fill height spot-checked against the approved specification with the filling line’s headspace allowance.
- ☐Neck finish and thread fit checked against your actual cap, pump or sprayer — not against a nominal gauge.
- ☐Application and removal torque measured on the assembled unit against the agreed window.
- ☐Air-pressure leak test at 0.6–0.8 MPa with the unit inverted and held, accepting zero leakage on the assembled pack.
- ☐Drop test where the route justifies it, run on packed units rather than bare bottles because packing changes how energy is absorbed.
- ☐Carton count, labelling and shipping marks checked against the packing list.
- ☐Retained samples kept from the batch for later comparison.
AQL 2.5: what it does allow, and what it does not
AQL is the most misread line on a QC report, in both directions. It is an acceptance sampling plan, not a defect allowance you can spend, and not a guarantee of zero defects.
Reading an AQL 2.5 result
Where a product cannot tolerate a sampled defect rate at all — a leak on a filled cosmetic pack, for example — the answer is a 100% functional check on that characteristic rather than a tighter AQL. The air-pressure leak test on the assembled unit is run that way, because a leak is not a cosmetic defect.
Your own inbound checklist, for when the container arrives
The supplier inspection and your inspection are not the same inspection. Three things are worth checking on arrival, and they are quick.
On arrival
- ☐Check the carton count and the shipping marks against the packing list and the commercial invoice.
- ☐Open one carton from the middle of the pallet rather than the top, because the first cartons loaded are not the ones that show handling damage.
- ☐Check the pallet plan and the packing condition against what was agreed.
- ☐Weigh a sample and compare against the approved specification and the weight on the QC report.
- ☐Fit your closure, pump or sprayer to a sample and check the thread engages and holds.
- ☐Check colour and print position against the approved standard sample, not against your memory of it.
- ☐Confirm the QC report matches the lot and the quantity you received.
- ☐File the retained sample from the middle of the shipment, so a question raised later has a physical reference.
What to ask for with the shipment
Ask for these at quotation stage rather than after the container is loaded. A missing file at the port costs far more than the file itself.
| Document | What it is | When to ask |
|---|---|---|
| QC report per lot | The inspection result for the batch you actually received, with the acceptance basis shown. | Agreed at quotation; issued per lot. |
| Packing list and commercial invoice | The export documents that accompany the shipment and drive clearance. | With the shipping documents. |
| ISO 9001:2015 certificate | The management-system certification we hold, issued by an accredited body after an external audit. It is not a product approval. | On request, before any payment and before any purchase order. |
| Product-specific test reports | Measured results on a specific sample or lot, with the method and the limits shown. They cover the lot tested and not the next one. | At quotation stage, for the tests your market requires. |
| Material declarations | The resin supplier declaration of what the material is and what it complies with, passed through us. | At quotation stage where food contact or a specific market applies. |
| Recycled-content records | The supply-chain record behind the recycled percentage claimed on pack for PCR and rPET or rPE content. | Before the artwork claims a recycled percentage. |
| Market-compliance file | The documentation assembled for your destination market, matched to it rather than issued as a general statement. | At quotation stage, so a gap is found before the order rather than after. |
Only ISO 9001 is a certification we hold. Everything else in that table is a document rather than a certification, and we label it that way so that the wording on your pack and in your file matches what is actually in the folder. If your market requires a certification we do not hold, we will say so at quotation stage rather than after the order is placed.
When a batch is questioned: what to ask for, and what you should get back
The value of traceability is realised at exactly one moment: when something is wrong after the goods have shipped. What matters then is whether the question can be answered by comparing the actual part rather than by reconstructing it from records.
What traceability links together
- ▸Resin lot, work order and finished-goods lot, in both directions.
- ▸Date and shift, so the run window is identifiable.
- ▸Moulding machine and the mould that produced the batch.
- ▸Batch records, inspection sheets and retained samples, archived so a shipment can still be traced well after delivery.
If you report a problem with a delivered batch, the production record is reopened, the retained sample is inspected and a root cause with a proposed resolution is provided in writing. That is a different conversation from one that starts with a photograph and an apology.
The five QC mistakes buyers make
- ▸Reading AQL 2.5 as a 2.5% defect allowance. It is a sampling plan and its acceptance criterion, not a budget you are entitled to spend.
- ▸Accepting a QC report without the acceptance basis. A result without a stated limit is not a result, it is a number.
- ▸Not keeping the approved standard sample. Without it, the tenth reorder is judged against memory rather than against the object you approved.
- ▸Inspecting the top cartons only. Handling damage and packing failures show up in the middle of a pallet, not on the lid.
- ▸Asking for documents after the container is loaded. A missing file at the port costs far more than the file, and it is the one part of an import that rework cannot fix.
Tell us what your market requires before the order
- ▸The specification and the acceptance basis you are working to, so the report can be issued against it.
- ▸Whether your market requires specific test reports, and which ones.
- ▸The sealing plan you want on the shipment and the packing standard you expect.
- ▸Any characteristic that cannot tolerate a sampled defect rate, so a 100% check can be quoted instead.
- ▸The destination market, so the compliance file is assembled against it rather than after arrival.
The QC report is issued per lot, and the ISO 9001:2015 certificate plus any product-specific test reports we hold are sent on request in English — before any payment and before any purchase order.
Inspection, testing and documents
Packaging QC questions
What is AQL 2.5?+
AQL 2.5 is an acceptance sampling plan. It defines how many units are inspected for a given lot size and how many defective units the plan will accept before the lot is rejected. It is not a licence to ship 2.5% defective, and it is not a guarantee that no defective unit reaches you.
What tests run on every lot?+
In-process checks run continuously: visual defect inspection every 30 minutes, wall thickness at four points per cavity, weight within ±2% of the approved specification, capacity spot checks, and neck finish and thread fit tested against your closure. On the finished lot we run AQL sampling, a leak test on the assembled unit, and a drop test on packed units where the route justifies it.
What is the drop test standard?+
A vertical free-fall of 1 m to 1.2 m, three times, with no cracking or loss of seal. Where a distribution route justifies it we drop test packed units rather than bare bottles, because packing changes how energy is absorbed.
Do you leak test the bottle or the assembled pack?+
The assembled pack. Bottles plus closures are pressurised to 0.6–0.8 MPa, inverted and held, and zero leakage on the assembly is the acceptance criterion. Testing the bottle alone would not prove anything about the pack the user receives.
What should I check when the shipment arrives?+
Three things quickly: carton count and shipping marks against the packing list, a sample from the middle of a pallet weighed and fitted with your closure, and the colour and print position against the approved standard sample. File a retained sample from the middle of the shipment.
What documents should come with the order?+
A QC report per lot, the packing list and commercial invoice, and on request the ISO 9001:2015 certificate and any product-specific test reports we hold. Material declarations, recycled-content records and market-compliance files are issued as documents — they are evidence rather than certifications.
How far back can a batch be traced?+
Every carton can be traced back to the resin batch it was made from, the moulding machine that ran it, the mould and the shift. Batch records, inspection sheets and retained samples are archived so a shipment can still be traced well after delivery.
What happens if I find a problem after the goods have shipped?+
We reopen the production record, inspect the retained sample from the batch and come back with a root cause and a proposed resolution in writing. That is why retained samples are kept rather than only records.
Tell us what your market requires
Send the destination market and the tests your buyer or regulator will ask for. We will tell you what we can document, what we hold and what we do not — before the order rather than after arrival.