The date code on your bottle is four different things, not one. MFG says when the bottle was made. PAO says how long the filled product stays good after opening. Expiry is a hard limit for food and some chemicals. Batch is the traceability key that ties bottles to a resin lot and a production window.
Quick answer
- MFG belongs to the empty bottle and changes every production run; PAO belongs to the formula inside it.
- Cosmetics usually carry PAO, because the filled product is judged from the day the customer opens it.
- Batch or lot number is the only code that survives customs, so it must be readable on at least one package level.
What do MFG, PAO, Expiry and Batch actually mean?
Every one of these four abbreviations is written on the same pack but answers a different question, and confusing them is the most common reason a date specification gets rejected at the filling line.
| Term | Full meaning | What it measures | Who owns it |
|---|---|---|---|
| MFG | Manufacture date, or date of manufacture | When the empty bottle or closure was produced | The packaging factory |
| PAO | Period after opening | How long the filled product stays usable once opened, usually printed as 6M, 12M, 18M or 24M beside an open-jar symbol | The formulator |
| Expiry | Expiry date or best-before date | A calendar date after which the filled product should not be consumed or used | The formulator, and often the retailer’s quality team |
| Batch / Lot | Batch number or lot number | Which production run the unit came from — resin lot, machine, shift, filler, date | Both parties, and it is the traceability key |
The distinction that causes the most confusion is MFG versus PAO. A bottle moulded in March and filled in August carries an MFG of March and a PAO of, say, 12M that only starts counting when the end customer opens the cap in a shop. The same bottle can therefore be filled up to two years after its MFG and still be perfectly good.
Why do cosmetics and food carry such different date systems?
Cosmetics and food are regulated differently, and the packaging follows the regulation. Food has a legal clock. Cosmetics largely has a validated-use clock. This is why a shampoo bottle and a sauce bottle never get the same code.
| Point | Cosmetics | Food and beverage |
|---|---|---|
| Default code | PAO in months, printed on the pack with an open-jar symbol | Expiry or best-before date, written as a calendar date |
| Clock start | The moment the sealed pack is first opened | The moment the product is filled |
| Unopened life | Governed by formula stability testing, expressed in months or years | Fixed by the shelf-life study and the date the code triggers |
| Stable-water products | Often rely on PAO alone, sometimes with a small-batch unopened note | Date is mandatory in most markets |
| Legal driver | EU cosmetics rules require the minimum durability information or PAO on the container | EU food-information rules require a durability date plus a lot identification code |
| US position | No mandated expiry date, but durability claims must be truthful and supportable | Dating and principal display panel rules apply, and dates must be truthful |
Practical consequence: for a cosmetic, the bottle plant prints the batch code and the filler prints PAO. For a food-grade bottle, the filler usually owns both the date and the lot code, because the date is part of the label. If you plan to sell the same bottle into both categories, confirm early who owns which code.
Where does each code go — bottle, cap, label or outer carton?
Four package levels are available, and each one answers a different traceability question. Most packs use at least two of them.
| Level | What it is used for | Typical marking | Readability requirement |
|---|---|---|---|
| On the bottle body | Retail traceability and consumer questions | Lot code, MFG date, PAO or expiry | Must be legible at arm’s length without a magnifier |
| On the cap or pump | Proof that a component matches the pack, and an anti-tamper signal | Short lot code, or a mould date if the closure is dated separately | Often marked on the inside face or underside |
| On the label | Mandatory consumer information and, for food, the legality of the date itself | Expiry or PAO statement, net contents, lot code | Highest scrutiny from inspectors and retailers |
| On the outer case | Warehouse, distributor and customs traceability | Full lot code, production date, case quantity, carton count | Must survive palletising, wrapping and a warehouse scan |
One practical rule we give buyers: put the full lot code on the outer case, and put a shortened but complete version on the bottle body. If a distributor asks you to trace one case back, you should not have to open cartons to answer.
What is the difference between inkjet coding, silk screen and hot transfer?
Date codes that change every day cannot be printed as decoration. They are applied at or after production as variable data, which is why the process choice matters more than the font choice.
| Method | How it works | Best for | Main limitation |
|---|---|---|---|
| Inkjet or laser coding | Printed at line speed on one or more package surfaces | Dates and lot codes that change per run | Needs a small flat or clear area on the bottle; fades if abraded |
| Silk screen | Fixed artwork pushed through a mesh, cured after printing | Static print such as a logo, a capacity mark or a fixed batch format | One mesh setup per version; not variable within a run |
| Hot stamping | Metallic foil transferred by heated die | Premium decorative marks, not traceability codes | Not used for variable dates |
| Roll-on or pressure-sensitive label | A printed label applied to the bottle or case | Variable dates, barcodes, multi-language legal text | Adds a material and an application step, and can lift under heat |
| In-mould labelling | Label placed in the mould and fused during blowing | Fixed label content at high volume, no rework step | Every version needs its own mould cycle; no variable dating |
For variable data, the comparison is straightforward: inkjet costs per printed unit with no setup, while labelling costs a setup per version but survives handling better. Our guide to bottle decoration options covers which decorative process fits which volume, and which printing survives e-commerce handling explains why a code that rubs off on a conveyor becomes a returns problem.
Can a cosmetic really claim a three-year shelf life?
Yes, but the number belongs to your formula, not to your bottle supplier, and it is conditional. A bottle plant can confirm the material, the closure and the barrier, and can tell you whether the pack is likely to hold a two-year claim. What it cannot do is set the shelf life for you.
Three inputs decide a realistic unopened shelf life, and all three sit outside the moulding process:
- Formula stability — the base, the emulsifier system, the preservative load, the fragrance level and the pH all move the stability clock.
- Fill and closure interaction — oxygen ingress, light protection and closure integrity determine how fast the formula degrades in that specific pack.
- Storage conditions — ambient temperature, direct light and humidity. A claim written for a controlled warehouse is not a claim written for a hot shelf.
So when someone asks us to print “3 years” on a bottle as a marketing line, the answer is that the print is easy and the claim is the hard part. The pack must be validated at that duration with that formula, and the claim must match what your testing supports. Printing an unvalidated period onto a pack is a liability you carry, not a factory issue.
What records do you need to keep for export batch traceability?
When a buyer, a distributor or a customs authority asks where a case came from, the answer should take minutes, not days. These are the records we build into every production lot and pass on with the shipment.
- Resin or raw-material lot number for each colour used in that run
- Mould number and the machine or line the bottles were produced on
- Production date and the production window, not just the day
- Masterbatch or colourant batch reference where the colour was pigmented
- Decoration version reference — which print artwork or label version was applied
- Closure batch reference and where it was produced
- Final QC results for that lot: capacity, leak, drop and weight checks
- Carton quantity, gross weight and CBM for the lot, as loaded
- Shipment reference linking the lot to the bill of lading
Ask for this as a per-lot record at the time of shipment. A traceability pack assembled eight months later from memory is not traceability. If you also ship labels, keep the label version number in the same file, because a dated pack with the wrong label artwork is a batch you cannot defend.
What are the three date-code mistakes we see most often?
1. Printing the bottle MFG date as the product expiry date. The empty bottle date says nothing about how long the filled product lasts, and printing it as a consumer expiry creates an immediate credibility problem on shelf. Separate the two fields in your specification and never reuse one code slot for both.
2. Coding only on the outer case. Case-level coding passes a warehouse check and then fails when a shopper calls about one bottle, or when the retailer mixes cases from several shipments on one shelf. Put a readable code on the bottle or on the label as well.
3. Accepting a code that nobody can read after handling. Inkjet on a curved surface, a code printed across a seam, or a code placed where the pump or the label wraps over it all produce illegible marks. Check the final pack, not the printing sample, and check it after the bottle has been through a friction test. Decoration and coding decisions are covered in more detail in our custom logo printing guide.
Frequently asked questions
What is the difference between a batch number and a lot number?
They are the same thing under two names. Both identify one production run. Some buyers write batch, some write lot, and some customs forms accept either as long as the same run carries the same string.
Does PAO mean the product expires after opening?
It means the stated period is counted from first opening. It is a use-by period for the opened pack, and it says nothing about the unopened shelf life, which is a separate claim.
Can one bottle carry both MFG and PAO?
Yes, and many cosmetic packs do. MFG applies to the empty container, PAO to the filled product, and they are dated by different parties. Separate fields, separate meanings.
Who decides the date code on the bottle?
The bottle producer owns the MFG date and the batch code. The filler owns the PAO or expiry date and the consumer-facing lot code. Confirm the split before printing, not after the pallets are wrapped.
Can date coding be added without changing the mould?
Usually yes. Inkjet or laser coding is applied at line speed and needs a clear print area, not a new mould. Variable dating on the mould itself is not possible, because in-mould labelling fixes the content at production.
Will silk screen or hot stamping let me print a variable date?
No. Silk screen and hot stamping produce fixed artwork per version. They suit a static lot format or a printed logo. Variable dates need inkjet, laser coding or a printed label.
About Shijin Packaging
Shijin Packaging Products Co., Ltd. has been manufacturing plastic packaging in Shenzhen, Huizhou and Guangzhou since 2003. We hold more than 2,000 existing moulds, run ISO 9001, GRS and SGS audited production, and ship roughly 500,000 bottles a day for cosmetic, personal care, household, car care and food-grade customers. We produce to 5,000 pieces per bottle model and per colour, and closures typically start at 5,000 to 10,000 pieces, so a coded trial pack fits the same minimums as an uncoded one.
Tell us which codes you need on which level: send the bottle capacity, the closure type and the markets you sell into, and we will tell you which codes belong on the bottle, the cap, the label and the case — and which of them we can print for you at production.