What Is Backlit Film?
Backlit film is a polyester (PET) base with a coated ink-receiving layer on one or both sides, plus a light-diffusing layer built into the base. Standard stock runs 100 to 220 micron. The diffusing layer is the part that matters: it is what turns a row of LED modules into an even field of light.
Light transmission on our grades sits between 35% and 55%. Lower transmission gives richer colour and deeper blacks; higher transmission gives a brighter face but flatter contrast. That single number is the main reason two films that look identical on a roll print very differently.
How it differs from banner material
PVC banner is opaque and made to be lit from the front. Put it in a light box and the print goes dark and blotchy, because the LED light cannot pass through the base. Backlit film is made for transmitted light, which means the ink has to carry more density than a front-lit print of the same artwork. A file prepared for front-lit banner, printed unchanged on backlit film, will look washed out.
Backlit film, backlit paper and duratrans
You will see this material sold as backlit film, backlit paper, duratrans or display film. In wide-format roll form it is almost always a PET film; paper is a loose trade term rather than a paper core. Duratrans is a photo-lab display film originally made for silver halide printers, and in roll form the word is now used loosely for any translucent display film. For inkjet, ask for a coated PET backlit film and check the ink compatibility, not the trade name.
PET or PVC Backlit Film?
Both exist. We make PET, and for light box work we would not recommend the PVC version. The difference is not only price.
| Property | PET backlit film | PVC backlit film |
|---|
| Dimensional stability | Stable; does not stretch under frame tension | Softens and creeps; sags in tall boxes |
|---|
| Heat under LED | Stable at typical LED box temperatures | Softens earlier; can yellow with heat and time |
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| Optical clarity | Clean whites, low haze | Slight warm cast, higher haze |
|---|
| Print coating | Eco-solvent, UV, latex, screen | Usually eco-solvent only |
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| Recycling stream | PET | Mixed PVC |
|---|
Both film types are translucent; the difference shows up after a season in a warm box.
Front Print or Reverse Print?
Front print puts ink on the side facing the viewer. It works with any backlit film, it is the default in most sign shops, and it is the right choice for most large-format work.
Reverse print puts the image on the back of the film, mirrored, so the viewer looks through the film at the ink. The film's own gloss surface becomes the front face, which gives deeper contrast and a glossier finish, and the ink is sealed behind the film instead of being exposed. It also protects the print during installation, because no one touches the image side.
- Choose reverse print for premium retail, airport and hotel boxes, where the face is unglazed and judged close up.
- Choose front print for large-format outdoor faces, short runs, and any job where mirroring the file is a practical problem for the print shop.
- Reverse print needs a film with a coating on the back side. A single-side coated film will not hold the ink.
- Do not print both sides of one film for a double-sided box. Ink density doubles and the image goes muddy. Use two films, or a purpose-made double-sided grade.
Specifications
Typical values for our standard grades. Thickness and transmission can be adjusted per order; this table is a starting point, not a catalogue limit.
| Grade | Thickness | Light transmission | Surface | Ink | Roll width | Best for |
|---|
| Standard backlit | 100 micron | 45-55% | Matte / satin | Eco-solvent, UV, latex | 0.914-1.52 m | Slim boxes, short-run retail |
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| Premium backlit | 150 micron | 40-50% | Satin | Eco-solvent, UV, latex | 0.914-1.52 m | General light box work |
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| High diffusion | 180 micron | 35-45% | Matte, high haze | UV, latex | 0.914-1.52 m | Edge-lit slim boxes, close viewing |
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| Heavy duty | 220 micron | 35-45% | Matte | UV, latex, screen | 1.07-1.52 m | Large faces, tensioned frames |
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| Reverse print | 150 micron | 40-50% | Gloss front, coated back | Eco-solvent, UV | 0.914-1.52 m | Premium retail, glass-free faces |
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Figures are typical, plus or minus 10%. Custom slit widths from 3,000 m2 per width. Core 2 inch or 3 inch.
Matching Film to Light Box Type
Box construction decides the film more than the artwork does. The variable that matters is the distance between the LED and the film: the shorter that distance, the more diffusion the film has to provide.
Slim crystal and edge-lit boxes, 25 to 45 mm deep
LED strips sit in the frame and fire sideways into the panel. Light has almost no distance to spread, so the film does the spreading. Use 100-150 micron with high haze; a 220 micron film here blocks too much light and leaves dim corners. Flatness matters more than thickness, because any wave in the sheet becomes a visible shadow line.
Aluminium boxes with back-mounted modules, 80 to 150 mm deep
Modules sit behind the film with enough air gap to blend. Standard 150-180 micron film is fine and moderate diffusion is enough. This is the most forgiving configuration, and the one most sign shops mean when they say light box.
Pop-up and SEG frames
A silicone-edge frame takes backlit fabric, not PET film. Fabric stretches into the groove and folds for transport; film cannot. If your frame is SEG, the medium is a coated backlit textile, which is a different product. We would rather say that than sell you film that will not fit.
Wall-mounted double-sided boxes
Two faces, one box. Use two films printed back to back, or a single heavier sheet at 180-220 micron if the frame clamps at the edges. A thin sheet in a large double-sided face will bow toward the warmer side.
Double-pillar and floor-standing boxes
The film hangs between two pillars under light tension. 150 micron with edge reinforcement is the usual choice; anything thinner will ripple along the top edge within a season.
Slim and aluminium light boxesWide-format print mediaLED modules and power supplies
Ordering: MOQ, HS Code and Lead Time
- MOQ: one roll on stock widths of 0.914, 1.07, 1.27 and 1.52 m. Custom slit widths from 3,000 m2 per width.
- Roll length: 50 m or 100 m, 2 inch or 3 inch core.
- HS code: 3920.62 for unprinted PET film in rolls. Printed graphics usually clear under 4911.10. Confirm with your customs broker before the shipment, not after.
- Lead time: 7-12 working days on stock grades, 18-25 working days for custom coating or slitting.
- Samples: A4 swatches free, freight collect. Roll samples on request for colour approval.
- Packing: PE wrap, kraft, pallet. Rolls stand on end for container loading.
