Check the roll before you open it. Photograph the label, the pallet and both roll ends while the packaging is intact, then identify the reflective face, measure the width in three places, weigh a cut square for grammage, and take thickness readings across the web rather than one in the middle. It is a short job per roll, and it pays for itself the first time a claim goes your way. Do it on every roll from every supplier, including ours.
Photograph the packaging before you cut it open
Photographs taken while the roll is still wrapped are usually the only evidence a carrier or insurer will accept that damage happened in transit rather than in your own workshop.
- The pallet as delivered. Two angles, wrap intact, showing the pallet label and any lean or crush in the stack.
- The label on every roll. Close enough to read every field: item, construction, width, length or net weight, roll number, batch.
- Both ends of every roll, square on. End crush and core collapse show here and almost nowhere else. An oval core, or wraps stepping sideways from telescoping, will not run straight on an unwind shaft — either can be transit crush or a winding fault, and the sealed-pallet photographs are what let you tell which.
- Water staining. Tide marks on the cardboard, softened board edges, rusty rings under the wrap.
Then count the rolls against the packing list, and note any damage on the carrier’s delivery note before you sign.
The order matters. Once the wrap is off, nobody can prove whether a crease came from a forklift in transit or from your own handling, and carriers and insurers both live in that gap.
Work out which face is the reflective one
Identify the reflective face before anything is unwound, because silver-on-silver constructions go up backwards easily and nothing about the finished job looks wrong until someone measures performance.
Hold a lamp low so the beam skims the surface:
- Gloss. The metallised film face is normally the brighter, harder, more mirror-like one; the reverse carries the substrate, scrim or adhesive and scatters more light.
- Emboss depth. The pattern is pressed in from one side, so one face has sharp-edged peaks and the other reads shallower. Diamond versus grid emboss explains how the two patterns differ.
- Telegraphing. On a woven laminate the scrim geometry shows faintly through the back; on a foil laminate the kraft or PE side is unmistakable.
Ask in writing which face is wound out before the roll ships, then tape a marker to the reflective face, so nobody has to decide again at six in the morning.
Measure the width in three places
Measure width on the unwound web at three points along the roll, because the outer wrap is the least representative reading available to you.
The outer wrap takes the handling: edges get folded by packaging and strapping, and a telescoped roll bruises its proud edge first. It reads narrow, which tells you about the wrapping, not the slitting.
Unwind a metre or two, lay a steel rule flat across the web and read it. Do not run a tape over the wound edge of a standing roll. Compare against the slit tolerance agreed in writing; every slitter has one.
Weigh a 100 x 100 mm square
Cut an accurate 100 x 100 mm square, weigh it in grams and multiply by 100 — that is grammage in grams per square metre, because a 100 mm square is one hundredth of a square metre.
Cutting accuracy dominates the error: a millimetre over on both dimensions is roughly two per cent on the answer, often larger than the difference you are trying to detect. So:
- Use a template. A steel square or a cutting die, not scissors and judgement.
- Cut several and average. Three to five samples, across the width and along the length.
- Match the balance to the sample. It has to resolve the sample to three figures. A square of thin film weighs a fraction of a gram, so either use a laboratory balance or weigh a stack of squares and divide. A kitchen scale reading whole grams cannot resolve film at all.
- Avoid the first wraps and the extreme edge. Neither represents the roll.
Grammage is usually the easiest number for buyer and supplier to agree on for laminated and embossed goods, because it does not depend on how you held the micrometer. If the units are unfamiliar, mil, micron, gsm and denier sets them out.
Thickness: many readings, never one on embossed material
One micrometer reading is meaningless — take readings across the width and along the length, and look at the spread rather than the number.
Use a flat anvil and a light, consistent closing pressure. Faint gauge bands along a flat film are common; a step change or a trend across the width is worth raising.
Embossed material cannot be measured this way. The anvil sits on the emboss peaks, so it reports pattern height rather than material, and the reading moves with where it lands and how hard you wind it down. Foil-bubble and foil-foam compress, which is worse again. Agree the method in writing before arguing about the result, and lean on grammage.
Length: diameter arithmetic first, unwind if it matters
You can estimate roll length from the outside and core diameters, but treat it as a sanity check rather than a claim figure.
With outside diameter D and core diameter d in millimetres, and t the wound thickness of one wrap also in millimetres (a gauge quoted in microns must be divided by 1000 first), length in metres is roughly π × (D² − d²) ÷ (4000 × t). The weak term is t: it includes trapped air and, on embossed goods, pattern height, so it always exceeds the material gauge.
If the roll is sold by weight, weigh it, deduct the core and cross-check: length in metres = net weight in grams ÷ (grammage in g/m² × width in metres). If the numbers still look wrong, unwind against a counter.
What is normal on the surface, and what is not
Winding lines, faint gauge bands and slight edge waviness are common on wound film; creases through the web, edge delamination, adhesive bleed and pinholes are not.
- Common. Ring marks from the wind-up, faint lanes of gauge variation, a baggy edge that pulls flat under tension, slight telescoping confined to the first wraps that does not affect running.
- Worth raising. Hard creases that will not pull out, delamination at the slit edge, adhesive bleed or blocking, tunnelling between plies, metallisation scratch lines running the length.
- Pinholes. Hold a length against a bare lamp in a darkened room. They matter enormously in a vapour-barrier application and much less in a light-bounce one.
These are general trade norms for wound film. What actually governs your delivery is the acceptance criteria written on the quotation and order confirmation.
If something is off, convert nothing
Once material has been slit, cut to length or laminated, it is very hard for anyone to establish what arrived, and most sellers’ and insurers’ terms treat converted material as accepted.
- Quarantine the roll. Label it, take it out of the run, tell the machine crew.
- Keep the label and the packaging. Roll and batch numbers tie the complaint to a production run.
- Write down what you measured and how. Instrument, number of readings, position on the roll.
- Report inside your inspection window. Your terms of sale will set one — check yours and report inside it.
- Send evidence, not adjectives. Photographs, the measurements you took and a retained sample.
Before the next order
An arrival dispute is often a specification question that was never settled before production. Agree the width tolerance, the face wound out and the measurement method before production, and the arrival check just confirms what you already knew — the point of specifying roll goods properly.
Send us the width, the construction and the application, and ask us to put the width tolerance, the grammage and the face wound out in writing on the quotation so you have something to check the delivery against.