Atarfil has long stood for technical integrity, durability, and fit-for-purpose design.

So why don’t we manufacture geomembranes simply to meet the GRI GM13 specification? Because we believe that spec compliance should be the starting point, not the finish line.

GM13 Was Once a Benchmark. Now It’s a Baseline – and an Easily Exploited One

GRI GM13 was established to provide a baseline of quality in HDPE geomembranes. But the industry has evolved, and so have manufacturing techniques. Unfortunately, so have shortcuts.

Manufacturers seeking to cut costs and inflate margins have learned to manipulate formulations and production methods to just barely comply with GM13.

This includes using:

• Round die extrusion instead of flat die (cheaper but less uniform)
• Minimal antioxidant packages focused only on passing HPOIT
• Recycled or reprocessed polymers disguised within spec

The result? Materials that technically pass GM13 tests but rapidly degrade in the field.

What GM13 Doesn’t Tell You

GM13 permits either Standard OIT or High-Pressure OIT testing. Nearly all manufacturers choose HPOIT because it primarily reflects HALS (Hindered Amine Light Stabilisers) — effective for UV protection but not for long-term thermal or chemical stability. Why? HALS are cheaper than the phosphites and phenols measured by Standard OIT.

This is critical:

OIT is the better predictor of long-term durability – including thermal ageing and chemical resistance.
Yet GM13 doesn’t require both. And without dual testing or tighter antioxidant criteria, inferior formulations can slip through, leaving asset owners exposed to premature failure.

There Are Many Ways to Meet GM13 – But Only a Few Ways to Achieve True Durability
That’s why Atarfil exceeds GM13 by default. Not because it’s required, but because it’s right.

Our commitment includes:

• AR and AC Grades: Chemically resistant options for alkaline and acid environments
• EVO Line: Simultaneous OIT + HPOIT resistance, optimised for real-world ageing
• Superior AO Packages: For long-term thermal and UV stability
• Flat Die Technology: Achieves superior thickness control and weldability
• Conductive Layers: For post-installation integrity testing
• Structured Texturing: Uniform asperities without compromising mechanicals
• Coloured Surface Layers: Reduces heat absorption, ideal for exposed conditions

We don’t believe in cutting corners. We believe in solving containment problems with products that work long after the datasheet has faded.

A Word on Strain Hardening Modulus (GM42)

Some point to GM42 as the new benchmark. While it’s a step forward, it also has flaws:

• SHM only correlates to SCR within a given resin system
• A single SHM threshold may result in products ranging from 500 to 5000 hours of SCR

For now, GM13 methods remains the more reliable benchmark, but only if you demand more than the minimum.

The Risk to Asset Owners

Too many containment failures occur within 10–15 years – not because the spec was wrong, but because the lowest possible version of the spec was accepted. Some manufacturers even alter formulations only when warranties are issued.
That’s a red flag.

When you increase performance requirements beyond GM13, it becomes harder to comply and easier to spot who’s really producing quality. Fewer shortcuts. Less variability. Real durability.

Why Atarfil Won’t Drop Standards

We won’t play the race-to-the-bottom game. We stand for:

• Transparency over manipulation
• Durability over datasheet theatrics
• Performance over profit

GM13 is no longer enough. For Atarfil, it never was.