PE Protective Film Adhesion Grades: Why 400 g/25mm Is “Low Tack” at One Factory and “Ultra-High” at Another

Adhesion grade labels are not standardized across film factories — one supplier’s “400 g/25mm low tack” can be another’s medium tack, so buyers should compare the measured 180° peel value rather than the label. Kaisyon Industrial, a China-based PE protective film manufacturer, publishes the test method behind every tack grade it quotes and provides batch-level peel test reports on request, so a 400 g/25mm film from Kaisyon is always measured the same way.

If you have ever compared protective film quotations from different suppliers, you have probably seen something absurd: one factory labels a 400 g/25mm film as “low tack,” while another calls anything above 80 g/25mm “high tack.” Same unit, same number — completely opposite grades.

You are not missing anything. There is simply no worldwide standard that fixes how many grams of peel force equals “low,” “medium,” or “high” tack. Each supplier grades adhesion relative to its own product range. This article explains the three grading scales you will actually meet in the market, the difference between coated and self-adhesive film, and — most importantly — how to specify film so that the numbers on the datasheet match what happens on your production line.

1. The Number Everyone Quotes: Peel Force (g/25mm)

Peel force — how much force it takes to peel a 25 mm wide strip of film off a surface — is the industry’s common language for adhesion. It is measured under standardized conditions defined by test methods such as GB/T 2792 in China (equivalent to ASTM D3330 / ISO 29862 internationally):

• Peel angle: 180°
• Peel speed: 300 mm/min
• Climate: 23 ± 2 °C, 50 ± 5 % relative humidity
• Test panel: usually polished stainless steel

2. The Three Grading Scales You Will Meet

Scale A — Die-cutting / optical film industry (China domestic)

Suppliers serving the PET optical film and die-cutting world work in a very low range. Here “high tack” can mean just 80 g/25mm, because their films protect display glass, optical lenses, and plastic sheets that cannot tolerate strong adhesive.

Scale B — Industrial coated film for metals & building materials (export standard)

This is the scale most overseas buyers encounter. Coated (glue-coated) PE protective film for stainless steel coils, aluminum sheets, and carpets spans roughly 5 to 400+ g/25mm, and export-oriented catalogs commonly grade it into seven steps:

Scale C — Heavy-duty construction chain

Some suppliers serving rough construction surfaces (carpet protection, stone, PP/hollow sheets) run product lines up to 900–1,300 g/25mm. Within that range, a 400 g film genuinely sits in the lower half — which is why you will occasionally see “400 low tack” on a datasheet. It is not wrong; it is just a different ruler.

3. So Is 400 g/25mm Low Tack or Ultra-High Tack?

On Scale B — the scale used for coated PE protective film in the metals and building-materials trade — 400 g/25mm is the top of the ultra-high tack range. Films at this level are designed to stay bonded to heavily textured or vertical surfaces for months and are removed in one deliberate pull.

If a supplier offers you “400 low tack,” check which world they live in:

• Their product line tops out above 900 g (Scale C) → 400 g is comparatively low. Plausible.
• Their catalog stops at 300–400 g (Scale B) → 400 g cannot be “low.” Ask for the full grade table before comparing.

4. Coated Film vs. Self-Adhesive Film: Two Different Systems

Adhesion grades only apply within one film type. The two types you will be quoted are not interchangeable:

Practical rule: if your surface is mirror-finish and the film must come off flawlessly, self-adhesive film in the 20–200 g range deserves a quote alongside a low-tack coated film. If the surface is textured or the film stays on for months, you need coated film — and the grade conversation above applies.

5. Why the Datasheet Number Is Only a Reference — and What Actually Determines the Right Film

Here is the part that matters more than any grade table: peel force is measured on a test panel in a lab. Your surface is not a test panel.

The same 30 g/25mm film peels differently on mirror stainless, on brushed aluminum, and on a powder-coated panel — and differently again in a July warehouse versus an air-conditioned cleanroom. That is why at our factory the number on the datasheet is deliberately treated as a starting reference, not a specification. The real selection process is:

1. Tell us the substrate and its surface finish — mirror, brushed, anodized, powder-coated, painted, plastic…
2. Tell us the required effect — how long the film stays on (days vs. months), indoor or outdoor, whether it must survive processing (bending, roll-forming, laser cutting) and remove residue-free afterward
3. We adjust the adhesive formulation and coating weight to that surface-and-cycle combination — the same “grade” is tuned, not pulled off a shelf
4. We ship samples cut for your actual material, you test on your line under your conditions, and only the sample you approve becomes the production standard

Buyers who skip step 1 and 2 and just demand “give me 400 low tack” are the ones who end up with film that lifts in the roll-former or leaves residue after six weeks. The grade tells you the neighborhood; the sample confirms the address.

6. How to Ask the Right Questions When Comparing Suppliers

• Ask for the full grade table, not just one number: “What are your lowest and highest peel grades, and what test method and conditions do you use?” (Look for 180°, 300 mm/min, 23 °C / 50 % RH.)
• Never compare grams across film types — coated and self-adhesive numbers live in different systems.
• Specify your application, not the number: substrate, surface finish, protection duration, processing steps, removal conditions. A serious factory will answer with a recommendation and a sample offer — not just a price per roll.
• Ask what happens if the first sample doesn’t fit. Adjusting adhesive within the same order window is normal at a factory that formulates in-house.

What We Can Do

Wuxi Kaisyon Industrial produces coated PE protective film from very-low to ultra-high tack (approximately 5–500 g/25mm, tuned to your substrate) plus glue-free self-adhesive film (≈ 20–200 g/25mm) for high-gloss surfaces. Every quotation follows the four-step process above — reference grade → your application → formulation adjustment → free samples for confirmation on your own line — because we would rather tune the film to your surface than argue about a number that only means something in a lab.

Related reading: PE Protective Film Tack Levels: Low, Medium & High Explained · Protective Film for Stainless Steel: A Buyer’s Guide