Why Covestro Desmopan forms the structural backbone of Wansen's GLS150 and GLS175 — and what the 319.47% elongation figure actually means for real-world durability.
The single largest variable in PPF performance is the quality of the TPU base polymer. Two films with identical nominal thickness can have radically different mechanical behaviour in the field — different elongation at break, different stress response underimpact, different long-term UV stability — purely because of differences in the underlying TPU chemistry and supply chain operations consistency.
Covestro (formerly Bayer MaterialScience) produces Desmopan, an aliphatic Thermoplastic Polyurethane that has become the de facto standard for premium PPF base film. The key reasons:
Both GLS150 and GLS175 share the same Covestro Desmokan base polymer and the same Ashland PSX adhesive system. The difference is nominal caliper — and caliper matters for both mechanical protection performance and installation ergonomics.
| Parameter | GLS150 | GLS175 | Test Method |
|---|---|---|---|
| Nominal Thickness | 150μm (±5μm) | 175μm (±5μm) | ASTM D2103 |
| Elongation at Break | 319.47% | >300% | ASTM D882 |
| Tensile Strength | ≥20 MPa | ≥22 MPa | ASTM D882 |
| 100% Modulus | ~8 MPa | ~9 MPa | ASTM D882 |
| Gloss (60°) | ≥92 GU | ≥92 GU | ASTM D523 |
| Haze | <1.5% | <1.5% | ASTM D1003 |
| UV Exposure (1000h) | Gloss retention >92% | Gloss retention >92% | ASTM G154 |
| Peel Adhesion (72h cure) | >16 N/25mm | >16 N/25mm | ASTM D3330 |
| Block Resistance | PASS at 50°C/4h | PASS at 50°C/4h | Internal method |
The additional 25μm in GLS175 provides measurably higher tensile strength and better resistance to stone chip impact — the kinetic energy absorption of a 175μm film is approximately 17% higher than a 150μm film at equal strain rates. However, GLS175 requires slightly more heat energy to reach full activation temperature during installation, and its greater stiffness reduces drape conformability on very tight radii. GLS150 is the preferred product for complex geometries with deep draws; GLS175 is preferred for flat panels where maximum stone chip protection is the priority.
Elongation at break is the most discussed — and most misunderstood — mechanical specification in PPF. A figure of 319.47% sounds like a guarantee of supreme ductility, and in one sense it is. But what does it mean in practice?
When a PPF film is subjected to a tensile test (ASTM D882), a strip of film is gripped at both ends and stretched at a constant rate of strain until it breaks. The elongation at break is the percentage increase in length at the point of rupture compared to the original gauge length. For a 50mm gauge length specimen, 319.47% elongation means the film stretched to 209.7mm before failing.
What this tells you about real-world performance:
High elongation at break does not mean the film is "soft" or lacks mechanical strength. The GLS150 achieves 319.47% elongation at break while maintaining ≥20 MPa tensile strength. These are not contradictory — elongation measures how far the material stretches before failing; tensile strength measures the force required to break it. A film can be both highly ductile and highly strong if the TPU formulation is well-designed.
GCC markets (Saudi Arabia, UAE, Qatar, Kuwait, Oman, Bahrain) present one of the world's most demanding UV and thermal environments for polymeric surface films. A dark-coloured vehicle in direct Saudi summer sunlight can experience surface temperatures of 85–95°C on horizontal panels. The PPF on those panels is subject to both thermal oxidation (accelerated by heat) and UV photodegradation simultaneously.
The Wansen GLS series topcoat formulation is specifically designed for this combined stress profile. Key design decisions:
After 1000 hours of accelerated UV exposure per ASTM G154 (using UV-A 340nm lamps), Wansen's GLS series films retain more than 92% of their initial 60° gloss reading. This is a critical performance threshold — films that fall below 85% gloss retention become visibly degraded and the vehicle appearance suffers.
The adhesive system used in Wansen GLS films is the Ashland PSX series of acrylic pressure-sensitive adhesives. Ashland (formerly a division of Lubrizol before the acquisition) has been the dominant supplier of PSA for premium PPF applications for over two decades.
The PSX adhesive is a crosslinked acrylic copolymer that achieves its bond strength through a combination of viscous flow (which creates intimate substrate contact) and covalent crosslinking (which creates long-term durability). Key specifications:
GLS150 (150μm) is designed for complex curved surfaces where installation ergonomics are critical — door creases, bumper facias, mirror housings. Its slightly lower caliper makes it more drapeable at activation temperature. GLS175 (175μm) is designed for flat or mildly curved panels where maximum stone chip and debris protection is prioritised. Both use the same Covestro Desmokan base and Ashland PSX adhesive system.
It means a 50mm sample of GLS150 film can be stretched to approximately 210mm before it breaks — that is more than tripling its original length. This high ductility allows the film to absorb stone impact energy by deforming rather than cracking. It also means the film can be pre-stretched during installation by up to 15% without risk of stress whitening or tears at the anchor points.
Covestro's Desmokan line offers the most consistent batch-to-batch molecular weight distribution of any aliphatic TPU available at scale. For a film supplier, this means the extrusion parameters remain stable over very long production runs, and the mechanical properties of the finished film are uniform from the first metre of a roll to the last. Inconsistent TPU leads to gauge variation, which leads to variable heat absorption and non-uniform installation performance.
The GLS series uses aliphatic TPU with good hydrolytic stability. However, as with any PPF installation, surface preparation before installation must include complete removal of any residual silicone, wax, or polishing compounds — these create a contamination layer that can lead to adhesive failure in humid environments. We also recommend post-heat curing at 65°C for 30 minutes in environments with relative humidity above 70%, to accelerate moisture expulsion from beneath the film during the critical first 48 hours.
Based on accelerated UV aging data (ASTM G154) and thermal cycling data, the GLS series is designed to maintain functional performance — defined as >85% gloss retention and >12 N/25mm peel adhesion — for a minimum of 7 years in GCC climates. Actual field performance depends on vehicle usage patterns, washing frequency, and whether the vehicle is garaged or kept outdoors.
Wansen exports GLS150 and GLS175 in roll widths from 1.22m to 1.83m, with custom slit widths available for distributor requirements. Contact our export team for technical specifications, pricing, and sample rolls.
View GLS Series TDS