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- Zhoukou city, Henan province, China
On a job site, plastic film does three different jobs: the vapour barrier under the slab, the dust sheet over finished work, and the curing cover on fresh concrete. They share a material and almost nothing else — the vapour barrier loses to a single sharp stone, the dust sheet is meant to be thrown away, and the curing cover lives or dies by how fast it goes down. Using one roll for all three is how two of the three jobs quietly fail. This guide separates them.
Construction film is not one product but three specification logics: the vapour barrier takes the top of the thickness range and lives on continuity, the dust sheet takes the bottom and lives on price, and the curing cover is judged by timing, edge weight and colour. Match the film to the job and all three work; share one roll across all three and two of them fail.
The most common sight on a mid-size site is a materials shed with one film specification in it, doing everything. Under-slab, masking, curing — whatever is left on the roll that morning is what the job gets.
Each of the three jobs fails in a different way, so each demands different things from the film. The vapour barrier fails by puncture and by seam, the dust sheet fails by being expensive, and the curing cover fails by timing and wind. A roll chosen for one is chosen against the other two, and the site that recognises this buys three thin specifications instead of one thick compromise.
The vapour barrier sits under the slab or inside the wall, and its whole job is continuity — one unbroken membrane between ground moisture and the finished floor. When it fails, the failure is not cosmetic: floor coverings lift, coatings blister, and the repair means opening the slab again.
Three requirements follow, and all of them sit at the hard end of the range.
Thickness takes the top of the range. The blinding layer always holds something sharp — stone, rebar offcuts, tie-wire. Crews walk on the film as they lay it. Film at the light end of the 30–200 mic range punctures on the first morning; the top end survives the laying day and the pour.
Continuity outranks gauge. A thick membrane with a poor lap is a membrane with a door in it. Overlaps are generous and sealed — the industry habit is to err on the wide side of the lap and tape the joint rather than trust gravity to hold it.
The preparation is the protection. Most vapour-barrier punctures do not happen in service; they happen on laying day, from what was already in the blinding. Sweeping and picking the base costs an hour. It saves a floor.
One more habit worth keeping: a visual pass before the pour. Laps that have shifted, boards dragged across the film, a patch where something sharp clearly went through — every one of them is fixable with tape in the laying daylight, and unfixable once the concrete covers it. The pour is the deadline for film repairs; everything after it is structural rework.
At the other end of the logic sits masking: covering finished work during paint, plaster and fit-out. Here the requirements invert. The film should be light, it should be wide, and it should be cheap — because the product is used for a day and binned.
Light gauge is correct, not a compromise: masking does not need puncture strength, it needs coverage. Wide film is what saves labour — a wall masked in one drop instead of three taped-together strips is faster to lay and leaves fewer gaps for overspray.
The wrong instinct here is buying premium film “because it lasts”. Masking film does not fail by tearing; it retires by coating — a film heavily loaded with paint is waste no matter how tough it was. Every extra micron spent on masking is spent on the bin.
Volume is where the wide roll pays twice: film bought on a 4 or 8-metre roll covers a wall in one drop, and the roll itself lasts the fit-out instead of being replaced per room. Cut-to-length off the same roll also handles doorways and floors better than folded retail sheets, which is why trade painters buy by the roll and keep a dispenser at the van door.
Fresh concrete gains strength because the water stays in it. If the surface dries too fast — sun, wind, low humidity — plastic shrinkage cracking appears while the crew is still on the next pour. The cover exists to keep that water in.
Three points decide whether it works.
Timing. The evaporation window opens as soon as the surface starts to set. The cover goes down as soon as the surface can take it — hours matter here, and a cover laid the next morning is covering a slab that has already cracked.
Edge weight. Wind lifts the edges first. Weighted edges, boards or sandbags along the perimeter — an uncovered edge is an uncovered slab.
Colour, by climate. Dark film absorbs heat; light film reflects it. In hot-weather curing, a light or white cover keeps the surface temperature down; where early heat helps strength gain, dark film works. Clear film lets the sun straight through and drives bigger day-night temperature swings through the cover — worth knowing before it is chosen by default.
Cold-season pours run the same logic in reverse. A cover on a winter slab is not keeping water in against the sun — it is keeping the surface from freezing overnight and moderating the day-night swing. The film choice is the same, the timing shifts: edges get weighted even harder, because winter wind is the dominant drying force, and any patch of uncovered slab is a patch that freezes first.
Colour does not change strength, but it changes behaviour on site.
| Colour | What it does | Where it fits |
|---|---|---|
| Clear | You can see through it | Masking where the object underneath must stay visible; inspection covers |
| Black | Blocks light, absorbs heat | Curing where warmth helps; areas that must be hidden |
| Blue | Stands out against site clutter | General site sheeting, the everyday identification colour |
None of the three is “better”. A crew that orders only black will end up masking with it, paying premium gauge to hide things nobody needed hidden; a crew that orders only clear will end up curing with it, and watching the surface temperature swing. Order colour by job, the same way thickness is ordered by job.
| Failure | What happened | The mistake behind it |
|---|---|---|
| Floor covering lifts months later | Vapour barrier punctured on laying day | Light film under the slab; base not swept |
| Plastic shrinkage cracks | Slab dried before it was covered | Cover laid late; edges not weighted |
| Consumables budget blown | Heavy film bought for masking | One spec ordered for three jobs |
None of these failures announce themselves at the time. The floor fails a season later, the crack is found at strip-out, the budget is found at the end of the month — which is why the sorting happens at the ordering stage, where it costs nothing.
Construction film runs from 1 to 8 metres wide, and width is the spec nobody prices properly. On the vapour barrier, width removes laps — every metre of extra width is a seam that does not need taping or trusting. On masking, a wide drop covers a wall in one pass. On curing, a full slab in one sheet, with no centre seam running down the middle of the pour.
Width, like thickness and colour, is set per job. It is also the reason there is no catalogue size on this product: the sites are not standard, so the film is not either.
Top of the thickness range, widest practical width, sealed laps, swept base. Judged in ten years, not ten days.
Bottom of the range, widest drop, clear for visibility. Judged by coverage per minute, disposed by the day.
Mid-range gauge, colour by climate and season, edges weighted early. Judged by the surface, hour by hour.
The ordering conversation that works starts with the job — “under-slab”, “masking”, “curing” — and lets the specification follow from it: which end of the thickness range, which width, which colour. Made-to-order is the whole point of this product: every dimension on the roll is chosen, and none of it is a menu.
Send the job, the covered dimensions and the exposure, and the specification comes back with the quotation — sample first for qualified buyers, 1000 kg per specification, 30+ days from confirmed spec to shipment.
Physically it can be laid for all three; practically two of the three will underperform. The vapour barrier needs the top of the thickness range, the dust sheet needs the bottom, and the curing cover is judged by timing and colour. One spec for three jobs is two specs ordered wrong.
Generously wide and sealed — the lap is the continuity risk, so the working habit is to err on the wide side and tape the joint rather than rely on the overlap staying closed.
As soon as the surface can take it. The evaporation window opens at initial set, and the first hours are when plastic shrinkage cracking starts — a cover laid that evening is often covering cracks that formed that afternoon.
For the vapour barrier under heavy traffic or over rough blinding, reinforced film earns its price — the reinforcement grid stops a puncture from running. For masking and curing, plain film at the right gauge does the job; reinforcement there is specification for its own sake.
The job (barrier, masking or curing), the dimensions to be covered, and the exposure — indoor or out, sun, wind, duration. From those, thickness, width and colour follow, and the quotation carries the specification.
Yinfeng Plastic (Henan Yinfeng Plastic Co., Ltd.) has produced polyethylene film since 1994 at a 72,000 m² facility in Henan, China, running 5 production lines with 200+ employees and an annual capacity of 55,000+ tons. Products are exported to 100+ countries. Inspection reports are issued by SGS; the factory is on the Sedex platform and has passed a SMETA audit; and the company is a China Strategic Partner of ExxonMobil.
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