Specification
Poly Mailer Materials
There is no standard material here to accept or decline. Film weight, opacity, finish and lining are separate decisions, and each one is made against what you ship rather than against a general recommendation.
This page sets out what is selectable and what each choice does. It deliberately contains no gauge figures in microns or mils, because the film available varies by market and by production run, and a number published here would not be the number in your carton.
Turn this into a specification
Tell us what you ship and we will apply everything on this page to your order, in writing.
Why we do not publish a gauge
A number without a method is not a specification.
Film thickness gets quoted in microns or mils, and the figures are not comparable between suppliers. Some measure the film flat, some measure the finished bag; some quote a target, some quote a minimum; and a film described identically can behave differently depending on how it was produced.
Publishing a figure here would give you something that looks precise and cannot be used to compare anything. Instead we describe films by what they do, and confirm the actual specification for your order in writing on the quotation.
If you need a numeric specification for an internal document or a tender, ask and we will provide what the supplier of your film can evidence for that run.
What is selectable
Every line is a choice. Nothing here is fixed until it is on your quotation.
| Option | Choices | What changes |
|---|---|---|
| Film weight |
| Governs how much concentrated force the bag takes before it fails, which matters for anything with a corner. |
| Opacity |
| Decides whether dark contents shadow through a pale film. Irrelevant on black. |
| Finish |
| Changes how printed colour reads and how visibly the bag shows handling marks. |
| Lining |
| Bubble absorbs impact; foam protects surfaces; neither resists crushing. |
| Construction |
| A gusset gives lofty contents somewhere to go, producing a square parcel rather than a barrel. |
| Recycled content |
| Feedstock type and proportion are confirmed per order with the supplier documentation behind them. |
Options shown are the choices we can quote against. The exact specification for your order — including film weight, closure and print method — is confirmed in writing on your quotation.
Choosing film weight against your contents
This is the material decision that causes the most failures when it is made on price alone.
Soft goods only
Garments, textiles and soft accessories put almost no stress on film. The standard weight is genuinely enough.
Anything boxed
A box corner concentrates the whole force of a drop onto one point. Move up a weight, or add cushioning.
Zips, studs, buckles
Hardware on a garment behaves like a corner from the inside. Heavier film, or a lining.
Large formats
The contents that need a big bag are heavier, and a big bag flexes more. We do not quote the lightest films above a certain size.
High-value contents
The per-unit saving on lighter film is trivial against the value at risk in one failure.
Storage affects material performance
Film is stable in storage; the adhesive on the closure is not. Heat, damp and direct sunlight degrade it, and a carton that has sat by a window for a year will seal noticeably worse than one stored in the dark. Keep stock flat, sealed, off the floor and out of light, and rotate so the oldest is used first. Where a material is designed to break down, storage matters more still, which is covered on the compostable material page.
Questions about materials
What are poly mailers made of?
Polyethylene film, in varying weights and finishes, sometimes with a bubble or foam lining bonded inside. Recycled-content and alternative-material films are available where the supplier can document what is in them.
What thickness of poly mailer do I need?
It depends on what is inside rather than on a number. Soft goods with no hard edges suit the standard weight; anything boxed, hardware-laden or heavy needs a heavier film or a lining. Tell us what you ship and we will specify it.
Are poly mailers waterproof?
The film resists rain and splashing, which is enough for a parcel left on a doorstep. It is not a sealed barrier — water can enter at the closure — so it should not be relied on for immersion or prolonged exposure.
Can I have the material specification in writing?
Yes. Every quotation states the specification we are quoting, and where you need supplier documentation for an internal record or a tender, ask and we will provide what exists for that film.
Specify a material
Describe what you ship — weight, shape, whether anything is boxed — and we will specify a film and put it in writing.