How to Specify TPU Film Thickness for Custom Clear Cosmetic Bags

By Jolian Lu · SEO Manager, Rivta

“Make it a little thicker” leaves important questions unanswered. Does the buyer want a different handfeel, a pouch that holds its shape when filled, or more support around the opening? Those requests should not automatically produce the same material change.

Start with the intended contents and the selected custom clear cosmetic bag construction. Then agree what the film specification must say and what the physical sample must demonstrate.

1. Separate film thickness from the feel of the finished bag

Thickness describes a dimension. A material grade, its hardness information and its surface finish describe other parts of the specification. As a documentation example, Covestro's TPU film technical data lists thickness and Shore hardness separately¹. A hardness value on a data sheet is not a substitute for measuring film thickness.

For purchasing, keep three references distinct:

• The material reference: supplier or internal material code, grade where available, and approved finish or tint.
• The thickness specification: nominal value, units, agreed allowable variation and measurement basis.
• The assembled sample: the actual bag, including its shape, base, seams, binding, zipper and intended contents.

Be precise about the layer being specified. A reading across both walls of a flattened pouch is not the thickness of one film wall. A bound edge or seam includes a different construction again. If the material is laminated or backed, distinguish the TPU layer from the total material thickness.

Use millimetres or micrometres explicitly: 1 mm = 1,000 µm. Avoid a bare number described only as “gauge” unless both parties have documented exactly what it means.

2. Put the measurement basis beside the thickness value

A nominal thickness is a target, not a complete acceptance rule. The buyer and supplier also need to agree how it will be checked and what variation is acceptable. Use a specification table like this before choosing between quotations.

The limits and reporting rules in this table are items to agree for the project, not default Rivta tolerances.

One possible reference to discuss with the supplier or testing laboratory is ISO 4593:1993 for mechanical thickness measurement of plastic film and sheeting². Its stated scope excludes embossed film and sheeting. For textured material, establish what the surface actually is and whether the proposed method applies; “frosted” and “embossed” should not be assumed to mean the same thing.

Confirm the applicable procedure with your supplier or laboratory before using it in the purchase specification.

3. Compare film swatches, then compare the assembled pouch

If the main decision is thickness, ask for a comparison that keeps other variables consistent where feasible. Give each candidate its own material and sample ID. If the supplier must change the grade, finish or construction as well, record that change: the comparison can still be useful, but it no longer isolates thickness.

At the film stage, review the identified swatches for the intended appearance and handfeel, alongside the recorded thickness results. Keep the approved swatch with the written specification. A photograph can document which sample was discussed, but it cannot replace a physical feel assessment or a thickness record.

At the bag stage, use the same intended bottle or product set for each candidate. Compare:

• How easily the contents enter and leave the opening.
• How the filled bag rests in the intended display or use position.
• Whether the zipper operates as intended when the pouch is filled.
• How the selected film works with the agreed seams, binding and corners.
• Whether the proposed packing arrangement preserves the appearance the buyer has approved.

Record the observation, the preferred sample and any correction. If a numerical performance requirement matters, agree its test method and acceptance criterion separately. A thickness reading alone does not establish leak resistance, load capacity or service life.

4. Describe the problem before asking for thicker film

When a sample disappoints, a precise observation gives the supplier a more useful starting point than “increase the thickness.” The following questions help separate a material decision from a construction decision; they are not diagnoses of an untested sample.

Ask for the proposed correction in writing. If it changes more than thickness, identify each change so the revised sample has a clear approval basis.

5. Approve the film and the bag as one linked record

The final approval should connect the material specification, the retained swatch and the assembled pouch. A useful sign-off names the approved material code, thickness and tolerance, measurement record, finished-sample ID and any agreed deviations. Where practical, buyer and supplier should each retain matching references.

Before bulk production, resolve any difference between the approved sample and the proposed production material. If the grade, finish, thickness specification or construction changes, agree which parts need review again. For the wider release process, use Rivta's cosmetic bag sample approval guide alongside this film-specific record.

Copy this structure into your next sampling request:

We are developing a custom clear cosmetic pouch for [intended contents and use]. The finished dimensions are [width × height × depth], with [opening, base and seam construction]. Please identify the proposed TPU film reference and finish, nominal single-layer thickness, proposed tolerance and measurement basis. If thickness options are available, identify what stays the same between the comparison samples and what changes. We will confirm the selected film against its swatch and approve the assembled pouch with our intended contents before releasing the final specification.

Add the project quantity, logo requirements, packing, destination market and target delivery date so Rivta can review the brief in context. If you have not selected a thickness, send a physical reference or describe the result you need; ask for a documented sampling proposal rather than guessing a number.