Micron is not quality: how to read a stretch film spec

Micron is the number on the box, so it is the number in the tender. It is easy to write into a specification, easy to compare across three quotes, and easy to check at goods-in with a gauge. Buyers have been trained to compare film by micron and roll price. Both are proxies, and both are misleading.

The trouble is what the proxy stands in for. Nobody buys film because they want a thickness. They buy it because they want a pallet that arrives standing, at a cost they can defend. Micron is not measuring that. It describes the web as it comes off the roll, before any of the things that decide the outcome have happened to it.

A gauge figure tells you roughly how much polymer you are buying per square metre. That is genuinely useful: it is most of what sets the price of the roll, and film is sold by weight. As a cost input it is fine. As a quality signal it is close to empty.

It says nothing about how far the film will stretch before it yields, whether there is any structure inside it, how it behaves against a sharp corner, how many revolutions it takes to hold your load, or how many metres of secure wrap you get from a kilogram. A pallet does not fail because the film was thin. It fails because the wrap lost its grip.

And the same figure from two suppliers is not the same film. A gauge number says how much material there is, not how that material is built or how evenly it is laid down across the web. Two rolls can carry the same micron on the label and behave differently the moment they are stretched onto a load.

Toreto ran its own wrap test in the plant in August 2026 — one pallet, one machine, the same 250% power stretch and tension settings throughout, with the film cut off and weighed after every run and the holding force measured on the finished load. Solid film went on at 23µ, 20µ and 17µ.

All three held the load at 9.9 kg per square inch. What the extra microns bought was weight and money: 200 g of plastic a pallet at 23µ, 174 g at 20µ and 140 g at 17µ, at roughly €0.48, €0.42 and €0.37 to wrap. A third of the thickness came out of the spec and the containment did not move. These are Toreto's own measurements, and the cash figures vary with film price and pallet size.

The same test rules out the opposite conclusion just as firmly. 12µ nano film, run alone at the same settings, held 7.6 kg/sq in — the weakest reading on the sheet — on 91 g at about €0.32 a pallet. Nano depends on a machine in good order and settings that are exactly right, so in practice most users wrap it twice: 11.9 kg/sq in, but on 182 g, about €0.64, and half the pallets per shift.

Thickness is not the variable. A thick film that is not reinforced still stretches and yields under a heavy load — it keeps giving under sustained tension and slowly releases its grip. Thickness is not containment. Structure is. Reinforced film carries banded reinforcement fused between its layers, and those bands do not yield, so a lighter gauge behaves like a much heavier one.

That is the row of the test that matters. Supersonic and Aerosonic at 16µ held 10 kg/sq in on 66 g of film, at about €0.32 a pallet — marginally more containment than the 23µ solid, on a third of the plastic, at around 50% fewer revolutions. Fewer revolutions is machine time, so the same wrapper put out twice as many pallets in a shift.

Read it for what it is: a description of the roll. Gauge, width, metres, core, sometimes a stretch rating. Every one of those is measured before the film meets your load, on the supplier's terms rather than yours. None of them is wrong. They simply answer a different question from the one you are asking.

The questions worth asking are answered on your pallet, not on paper. How many grams of film end up on a finished load? How many revolutions, and how long does the cycle take? How hard is the wrap actually holding when the pallet leaves the machine? How does the film behave on your worst corner? A supplier who will come and measure those is telling you something. A datasheet cannot.

Specify the outcome. Describe the load — weight, height, stability, overhang — and the journey it makes. State the containment the wrap has to reach on a representative pallet, the cycle time the line needs, and the fact that you will award on measured performance. If a micron figure has to stay in the document, put it in as a reference point rather than a requirement, so a better-engineered film is not disqualified for being thinner.

Then run the trial and add it up. The number that matters is the fully-loaded cost of wrapping one secure pallet: film, labour, machine time, damage and re-wrapping combined. That is the figure Toreto engineers for, and it is not the micron on the box.