Compostability is tested under defined end-of-life conditions; it does not mean a correctly manufactured product should fall apart on a warehouse shelf. Premature changes usually point to a mismatch among formulation, packaging, storage, transport exposure and the intended service life. A good purchasing specification controls those factors before an order ships.
The storage risks buyers should control
| Risk | Possible commercial effect | Control to agree |
|---|---|---|
| Heat | Blocking, deformation, seal changes, embrittlement or shortened usable life. | Supplier’s maximum storage and transport exposure; keep away from heaters, roofs and hot containers. |
| Moisture and humidity | Resin drying problems, hydrolysis during processing, dimensional or mechanical changes and damaged cartons. | Sealed moisture barrier, desiccant if specified, dry warehouse and reseal rules for opened material. |
| UV and direct sunlight | Colour change, surface ageing and loss of mechanical properties. | Opaque packaging and indoor storage away from windows or outdoor staging. |
| Long or unknown inventory age | Stock may exceed its validated shelf life before conversion or use. | Manufacture date, lot code, expiry or re-test rule and first-expire-first-out rotation. |
| Stacking and compression | Crushed cores, distorted rolls, telescoping or damaged seals. | Pallet pattern, maximum stack height and handling method in the signed pack-out. |
| Contamination | Odour, print or seal problems, food-contact concerns and loss of traceability. | Closed original packaging, clean segregated storage and controlled partial-roll handling. |
Do not invent one shelf-life number for an entire material family
“PLA,” “PBAT” and “starch blend” describe broad material families, not one product. Resin molecular weight, blend ratio, additives, film gauge, print, seals, roll tension, outer packaging and climate all affect stability. Shelf life should therefore belong to an exact grade or finished SKU under stated storage conditions.
Ask the supplier to define the start point — manufacture, packing or shipment — and what happens at the end of the period. Some products require disposal after expiry; others may be re-tested against agreed acceptance criteria. Record the rule instead of assuming an expired product remains suitable.
Warehouse SOP for finished bags and film
- Record every lot on receipt. Capture supplier, SKU, formulation or revision, batch, manufacture date, quantity and pallet condition.
- Inspect before put-away. Look for wet cartons, torn liners, crushed cores, telescoped rolls, blocking, odour, colour change or brittle film.
- Store in the original sealed pack. Do not expose rolls or bags to open warehouse air longer than necessary.
- Control location. Avoid sun-facing walls, roofs, steam lines, heaters, exterior staging and damp floors.
- Rotate by expiry or re-test date. First-expire-first-out is more useful than first-in-first-out when lots have different validated periods.
- Quarantine abnormal stock. Do not mix damaged or out-of-condition material with released inventory.
- Check before conversion or dispatch. Test the critical function — seal, unwind, puncture, stretch, cling or print adhesion — for older or exposed lots.
Resin storage and drying are separate from finished-product storage
Converters must follow the resin-grade technical data sheet for unopened storage, drying temperature, drying time, target moisture and allowable residence time. PLA and some blend components can be sensitive to moisture during melt processing. Excessive heat or incorrect drying can also damage material. A generic blog value should never outrank the resin supplier’s current processing instructions.
Finished bags and films need their own controls for roll geometry, blocking, seals, print and functional performance. Do not copy a resin shelf-life statement onto converted goods without validation.
Transport exposure belongs in the specification
A warehouse may be controlled while a shipping container, truck or port staging area is not. Ask the supplier to define packaging protection and any maximum excursion. For hot-season routes, consider a temperature indicator or data logger during validation shipments. If a pallet arrives outside the agreed condition, quarantine it and compare functional test results with an unexposed control.
What to request from a supplier
- Current technical data sheet and SDS for the exact resin or product.
- Validated shelf life with stated storage conditions and start point.
- Transport and short-term excursion limits, if established.
- Original packaging, resealing, partial-roll and stacking instructions.
- Lot coding, manufacture date and expiry or re-test rule.
- Acceptance tests for older, exposed or returned stock.
- Change-control notification when formulation or packaging changes.
For a custom order, include these requirements in the OEM/ODM brief. If the material choice is still open, use the PLA, PBAT and starch comparison before requesting samples.
Editorial review: 14 September 2026. Always use the current product-specific technical data sheet and signed specification; generic storage guidance cannot establish a warranty.