Window film is a low-unit-price, high-variance product. Two suppliers can quote the same "8 mil security film" and ship two different constructions, with different adhesive systems, different release liners and different failure modes. The purchasing job is not finding the lowest number; it is making sure the two quotes describe the same object.
What a usable datasheet contains
- Construction — base film material (PET), adhesive type (pressure-sensitive acrylic vs. dry adhesive), liner type.
- Optical and solar values — VLT, TSER, SHGC (or SC), UV rejection, IRR with the wavelength range stated.
- Physical values — thickness in micron and mil, tensile strength, elongation, adhesion after 24h, haze.
- Roll format — width, length, roll diameter, gross weight, core size.
- Durability — warranty period and what voids it.
If a quote arrives without SHGC, the film was never tested as a system — you are comparing marketing numbers. A supplier who can send a datasheet with a wavelength range and a test method is usually a supplier who coats rather than resells.
Comparing quotes that are not comparable
The three variables that move price most are width, thickness and adhesive. A 1.52 m master roll costs less per square metre than the same film slit to 0.9 m, because slitting wastes material and adds a step. Quoting "per roll" hides this. Ask every supplier for:
- price per square metre, at a stated width and length;
- MOQ per width, not per product;
- what changes at the next price break — one pallet, one 20ft, one 40ft.
Container arithmetic
A 20ft container holds roughly 28 cubic metres of usable volume, but film is light and bulky: the limit is usually volume and roll crushing, not weight. Before you commit, ask for the packed carton dimensions and the number of rolls per carton, then calculate the real fill. Two practical points:
- Rolls should ship on end or in purpose-built cartons with end supports; flat-stacked rolls deform under their own weight in summer.
- Mixed containers are normal for distributors — 60% solar, 30% safety, 10% privacy — but each SKU needs its own carton count, or the loading plan will not close.
Samples and the first order
A sample should be a production sample from the current batch, not a bench sample, and it should carry the batch number. Test what matters for your market: haze on a white wall, adhesive residue after peeling, colour shift against a known reference. Then order the first container with an agreed inspection step — photographs of carton labels and a batch record before loading is a reasonable ask and separates serious factories from traders.
Terms that prevent arguments
- Incoterm — FOB vs CIF changes who owns the risk at which point. Both are fine; ambiguity is not.
- Tolerance — agree acceptable variance on length per roll (±0.5% is common) before production.
- Claims window — how many days after arrival to raise a quality claim, and what evidence is required.
None of this is exotic. It is the difference between a first order that repeats and one that ends in a email thread about who is responsible for sixty rolls of the wrong shade.
