Two different material strategies claim the word "blackout" — one absorbs light through stacked pigment coatings, the other reflects it with a single metallized layer. Window covering manufacturers who understand the difference can spec total blackout with less material, not more.
Blackout fabric blocks light by building up two or three layers of opaque foam coating on a woven face fabric, while blackout film blocks light with a single vacuum-deposited aluminum layer laminated into the shade's internal structure — the two approaches differ not in the outcome they promise, but in the physical mechanism (absorption vs. reflection) and the number of process steps needed to get there.
For a curtain, roller blind, or cellular shade brand, this distinction is not academic. It determines how many production steps are needed to hit a 100% opacity spec, how consistent that opacity is across a large-format roll, and how the finished product behaves after years of folding, exposure, and cleaning.
Coated blackout fabric is classified by how many coating passes it took to make it opaque.
Textile mills producing blackout lining generally sort their output into three light-blocking tiers: light-filtering fabric blocks roughly 50–80% of incident light, room-darkening fabric blocks roughly 90–95%, and true blackout fabric is marketed at 99%+ blocking (Mermet USA, fabric blackout measurement reference). Reaching the top tier is a coating problem, not a weaving problem — a woven or knitted base fabric alone is never opaque enough on its own.
The industry solves this by applying foam or acrylic coating in sequential "passes":
Because each pass is a separate coating and curing step, opacity in this approach is a function of how many layers a mill is willing to run — and each of those coating layers is a bonded, non-structural interface rather than a single continuous barrier material. Textile research on coated and laminated fabrics notes that adhesion at this interface depends on the base fiber, pretreatment, and coating chemistry, and remains a known point of failure under repeated mechanical stress and washing (Textile School, Coated and Laminated Textile Fabrics).
Metallized film doesn't build up opacity in layers — it reflects light off a single aluminum surface.
Vacuum metallizing is a physical vapor deposition process: aluminum is evaporated inside a vacuum chamber and condensed onto a moving polyester (PET) carrier film as a continuous, nanometer-thick metal layer. The aluminum atoms strike the film surface at high velocity and bond into it, producing a dense, continuous reflective layer rather than a coated-on surface treatment (Dunmore, Vacuum Metallization Films & Fabrics). Because the aluminum layer reflects incident light rather than absorbing it, a single deposition pass can outperform multiple pigment coating passes for pure blackout.
Expansteel's ES-VM Plus is built on this mechanism and is specified for total-blackout applications:
Same end goal, different bill of process — the table below lines up the two approaches on the variables that matter to a converter's line.
| Attribute | Coated Blackout Fabric (2-/3-Pass) | Metallized Film Composite (ES-VM Plus) |
|---|---|---|
| Light-blocking mechanism | Absorption — stacked opaque pigment/foam layers | Reflection — vacuum-deposited aluminum layer, OD ≥2.0 |
| Opacity achieved | Up to ~99%+ claimed, dependent on pass count and coating consistency | ≈0% measured light transmission across the film |
| Layer count to reach full blackout | 2–3 sequential coating passes on a woven/knit base | 1 metallizing pass + 1 non-woven lamination pass |
| Durability of the blocking layer | Bonded surface coating; adhesion can be affected by washing, heat, and repeated flexing | Aluminum atoms bond into the PET carrier at deposition; reflective layer is UV-aging tested against oxidation |
| Weight contribution | Adds foam mass with each additional coating pass | Nanometer-scale aluminum layer on a thin PET carrier (12 μm standard) |
| Cost logic | Scales with number of coating passes and cure cycles needed to reach target opacity | Scales with film thickness/width; one deposition process replaces multiple coating passes |
| Processing / conversion method | Knife-over-roll or calendering coating, integrated into the face fabric itself | Supplied as a roll-good film for lamination into the shade's fabric/film/non-woven stack |
| Typical finished product | Dyed drapery, curtain lining sold as a complete fabric | Blackout core laminated inside cellular shades, pleated shades, roller blinds |
Metallized film is not sold as a finished curtain — it is the blackout core inside a laminated shade structure.
In a finished shade, the metallized film sits between a decorative face fabric and a non-woven backing, forming a three-layer composite: face fabric / metallized film core / non-woven layer. The aluminum core does the light-blocking work while the fabric and non-woven layers provide the visible finish, hand-feel, and structural backing the shade needs. This construction shows up across several product categories:
Expansteel produces ES-VM Plus through a dual process — vacuum metallizing followed by non-woven lamination — across 5 production lines, with a maximum web width of 2400mm and manufacturing capacity split between Taiwan and China. That width and dual-origin footprint is sized for shade manufacturers running large-format roller and cellular shade lines, not for small-batch converters.
Four numbers on a technical data sheet tell a converter whether a metallized film will actually laminate and perform as spec'd.
No. Blackout lining fabric is a finished, coated textile sold as-is for curtains. Blackout film is an upstream material — typically a vacuum-metallized PET film — that shade and curtain manufacturers laminate between a face fabric and a backing layer to build their own blackout composite.
Lamination compatibility depends on the film's surface tension and the adhesive/lamination process used. ES-VM Plus is engineered with surface tension optimized on both faces (≥48 mN/m aluminum side, ≥44 mN/m non-aluminum side) specifically to support reliable bonding during non-woven lamination.
Optical density (OD) is a logarithmic measure of light blocking, where OD = -log10(transmission). An OD of 2.0 means no more than about 1% of incident light passes through that layer. Because OD is logarithmic, small increases in OD represent large increases in blocking — which is why metallized film can reach near-0% transmission with a single reflective layer.
Untreated aluminum layers can be prone to oxidation, which is why blackout-grade film should specify UV-aging testing on the aluminum layer. ES-VM Plus's aluminum layer is UV-aging tested for resistance to oxidation and discoloration, so it is designed to retain its reflective blackout performance rather than degrading visibly over the product's service life.
12 μm is a common standard thickness for laminated blackout film cores. Manufacturers needing more rigidity for larger cell structures or stiffer pleats can specify thicker gauges — ES-VM Plus is customizable from 6 μm up to 100 μm.
Yes, within the supplier's production line capability. Expansteel manufactures ES-VM Plus across 5 dedicated production lines with a maximum web width of 2400mm, with manufacturing footprint in both Taiwan and China to support large-format roller and cellular shade production.
Data source: Expansteel TDS measurements, updated 2026-07. Industry reference sources: Mermet USA, Dazian, Textile School, Dunmore.
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