Holographic TPU Cosmetic Bag: Three Layers, One Seam

A holographic TPU cosmetic bag is a laminate wearing the costume of a single material. The film underneath is a clear thermoplastic polyurethane; the rainbow is a micro-structured layer bonded to it; the surface carries a hard coat that keeps the effect from rubbing off. Three layers, one appearance, and three different ways to fail.

This guide covers what the layers are, why the seam matters more than the film, the three failures specific to a holographic pouch, and the documents a buyer should hold before the order rather than after it.

What the Three Layers Do

Each layer has one job, and each is specified separately even though the pouch is bought as one sheet. A quotation that names only "holographic TPU" has named the appearance and not the construction.

• The base film — decides flexibility, cold resistance and weldability. TPU stays soft below freezing, which is why it is preferred over PVC for a pouch that travels.
• The holographic layer — a micro-embossed structure that diffracts light, either as a rainbow sheen or as a pattern. It is thin, and it is the layer that delaminates when the bond is weak.
• The hard coat — a clear top layer that resists abrasion and fingerprinting. Without it the effect dulls within weeks of being handled, and the pouch reads as scuffed rather than as iridescent.
• The bond between them — an adhesive layer that is invisible in the sample and decisive in service. A pouch that delaminates does so at the edge first, where the film is cut and the layers are exposed.
• The seam method — TPU can be welded with high frequency, which joins the layers into one continuous sheet, or sewn, which leaves a line of holes through all three.

The table compares the three effects sold as holographic, because they do not age the same way.

Three Failures Specific to Holographic Film

A plain clear pouch can only really fail by leaking. A holographic one has three additional ways to lose its appearance without ever leaking a drop.

Delamination starts at the cut edge

Every cut edge exposes the bond between the holographic layer and the base film, and that edge is the entry point for air and handling. A pouch with a weak bond shows a milky halo along the seam within weeks, and once the layers separate the effect cannot be restored. The test is simple: press a strip of tape across a cut edge, lift it, and see whether anything comes away with it. A bonded film gives up nothing.

The weld line goes white

High-frequency welding melts the TPU to join it, and the heat disturbs the micro-structure of the holographic layer. A correctly set weld produces a narrow, slightly matte band that reads as a design line. An over-heated one produces a white, opaque stripe 3 to 4 mm wide that no longer diffracts at all. On a pouch where the weld runs around three sides, that stripe is the most visible feature on the product.

The rainbow fades before the film fails

UV exposure degrades the embossed structure before it degrades the TPU, so a pouch can remain perfectly strong and completely flat in appearance. This is the quiet failure: nothing tears, nothing leaks, and the product simply stops looking like what was sold. Hours under a lamp with a colour and gloss reading attached are the only way to predict it, and the figure should be on the file rather than in a conversation.

Where the Zip Interrupts the Weld

A welded pouch has one continuous seam until it reaches the opening, and the opening is where the construction stops being a weld and becomes a sewing job. That handover is the weakest part of a holographic pouch, and it is the part nobody photographs.

• The zip tape has to be sewn to the film — a needle through a holographic laminate leaves holes that the film cannot close, so that line is no longer watertight even though the rest of the pouch is.
• The end of the weld meets the end of the zip — two different processes arrive at the same 10 mm of edge, and if they overlap the film stiffens and cracks there; if they leave a gap, the gap is an opening.
• A binding hides the transition and adds thickness — a fabric binding solves the appearance and adds 1.5 mm to the edge, which changes how the pouch sits when closed.

Look at the two points where the weld ends at the zip on the sample, one at each side. A clean pouch shows a short, even transition with no white mark and no visible gap. A pouch that will fail shows a lump, a bubble or a hole, and it shows it immediately rather than after a season.

Documents to Hold Before Ordering

Five items make up a file that answers the questions a retailer will eventually ask about a metallised, multilayer film.

1. A material declaration naming TPU — the base polymer, the plasticiser position and the film thickness in microns, so that the pouch is not described as clear PVC by a customs officer reading a generic code.
2. A restricted substances statement — REACH and RoHS for the EU, and the state-level position for the United States, covering the film and the printed ink separately.
3. UV hours with a measured change — the exposure time and the gloss or colour shift that followed, because "UV stable" describes a grade family and not a result.
4. A recycling position stated honestly — a multilayer holographic film is not a mono-material stream, so any recycled-content claim belongs to the base film and should say so.
5. A batch link to the roll — holographic effects vary between film lots more than plain films do, so the roll number is what a second delivery should be compared against.

Holographic pouches are built inside the custom spec bag programme, and two finished references are the iridescent TPU cosmetic pouch and the holographic PVC travel pouch. Zip tape, pull tabs and any wrist loop are assembled in-house, the webbing trim is woven to 2000N+ break strength, and the testing page lists the light and abrasion methods applied to films.

FAQ: Holographic TPU Cosmetic Bag

A holographic TPU cosmetic bag is bought for an effect that lives in a layer a fraction of a millimetre thick. Check the bond at a cut edge, check the weld for a white stripe, check the UV hours, and describe the layers in the file rather than the appearance. The pouch will still look like one material; the specification should not pretend that it is.