How to Write a Film Specification Your Supplier Will Thank You For

Most disputes between film suppliers and converters are not technical disagreements. They are misunderstandings of what was actually specified. A good specification is short, measurable and agreed, and it protects both parties: the supplier knows exactly what to produce, and the buyer knows exactly what to accept.

The fields that matter

Start with the end use in one sentence, because it resolves most downstream arguments. Then the essentials: base polymer and grade, nominal thickness with tolerance and the measurement method, surface treatment side and level, the sealing or adhesion requirement with its test method, colour and appearance standard, core size, roll length, maximum diameter, packaging and labelling format, and the delivery schedule. Add the compliance documents you need - food contact declarations, REACH or RoHS statements, certificates of analysis - so they are agreed before production rather than after.

Nominal is not the same as measured

A thickness tolerance only has meaning together with the test method. Gauge measured by capacitance, by optical means or by a mechanical micrometer can differ, particularly on very thin films. Ask the supplier which method is used for the figure on the certificate of analysis, and accept that method as the reference. The same applies to haze, gloss, seal strength and coefficient of friction: each has several possible test methods with different results.

Specify what you will measure

There is a difference between a property you would like and a property you will test on receipt. Requirements that cannot be verified on incoming goods create friction every time. If the property matters commercially - seal window, coefficient of friction, print adhesion, thermal shrinkage - ask for a defined test method and a defined acceptance limit, and reference it in the purchase order.

One document, one revision number

Keep the specification in a single controlled document with a revision number and a date. When something changes, issue a new revision rather than an informal email, and reference the revision in every purchase order. Both sides then know exactly which version applied to which delivery, which is what makes a claim or a credit note straightforward to settle.

A note on samples

A sample reel is not a specification, but it is a valuable companion to one. Approve a sample and hold it as the reference for colour, surface, print behaviour and general appearance, and store it in controlled conditions. When a delivery differs from the approved sample, that reference removes the debate about whether the material has changed.

Asia Pacific Industry Group supplies product data sheets with nominal values, tolerances, test methods and compliance statements for every grade we manufacture, and our technical team can review a draft specification before you issue it. Sending a draft for comment costs nothing and usually removes at least one round of trial material.