Notes from the coating line

Short technical notes on AlOx, metallized film and the regulations moving around them — written for converters who have to defend a structure in front of their own customer. Published as new lots are run.

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The notes

Three notes are published — PPWR, how to read a metallized spec sheet, and why 18 µm is the working gauge. Nothing is gated; ask the question directly if the answer is not here.

Regulation · PPWR

What PPWR changes for a transparent barrier pack

The recyclability requirement lands on the converter, but the decision starts at the film. Which documents to prepare now, and which claims to stop making.

2 November 2026 6 min read Published

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In the note

Which structures the PPWR recyclability requirement actually reaches, and which it leaves alone.
The documents a converter should hold before making a mono-material claim to a brand owner.
Claims that are no longer defensible on a transparent barrier pack — and what to write instead.

Technical · specification

Reading a metallized film spec sheet: OTR, WVTR and the test conditions

Two rolls can carry the same barrier claim and behave differently on your line. The four conditions that decide whether a number is comparable.

28 Sep 2026 8 min read Published

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In the note

Why OTR and WVTR numbers are only comparable at a stated temperature, humidity and method.
The four conditions to check first when two suppliers quote the same barrier figure.
How to write the condition line into your own customer specification so it cannot be re-quoted loosely.

Materials · AlOx

Why 18 µm is the working gauge for AlOx-coated BOPP

Thinner runs faster and converts worse; thicker costs resin for barrier you already have. Where the gauge settles, and what it does to seal and print.

09 Sep 2026 5 min read Published

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In the note

What changes on the line when the gauge drops: tension, registration and seal window.
Why the coating carries the barrier, so thickness is no longer the lever it was on a laminate.
Where a different gauge is justified instead of 18 µm — and which grade to trial when it is.

Longer guides

Two detailed guides sit outside the notes list: one on AlOx BOPP in mono-material PP structures, one on metallized PE in recyclable PE structures.

AlOx BOPP in mono-material packaging

Where the coated web sits in a PP/PP structure, what it buys, and when it is the wrong call.

Metallized PE in recyclable structures

Why a PE/PE structure with a metallized layer sorts and reprocesses as PE — and what it costs in barrier.

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Ask it directly. Technical questions get an engineer's reply, not a brochure — and the answer often becomes the next note.

Ask a technical question ALOX BOPP specification

What we will not publish

Certificate numbers, customer names and price. Everything else that is measured on a roll — thickness, width, barrier at a stated condition — belongs on the lot data that ships with the sample.