What Is Ultrex® Pultruded Fiberglass?
Infinity windows and doors are built on the strength of something truly unique—Ultrex® pultruded fiberglass. Patented by Marvin, Ultrex combines fiberglass-reinforced strength with an acrylic exterior finish that resists fading, warping, and cracking. The result? Exceptional performance, energy efficiency, and durability—ideal for Colorado’s unpredictable climate. From freezing winters to blazing summers, Ultrex holds strong, making it the smart choice for homeowners who want long-lasting beauty and real peace of mind.
Ultrex fiberglass has an amazing strength-to-weight ratio, which is one of the reasons why it’s the material of choice for boats, bridges, guard rails, and ladders. It’s highly durable, doesn’t corrode, resists rot, and resists expanding and contracting in temperature swings. In comparison to longitudinal tensile strength.
What Is Pultrusion?
Pultrusion is a highly precise manufacturing process that combines the words “pull” and “extrusion.” It continuously pulls fiberglass strands through a heated die, forming rigid profiles with exceptional dimensional stability and strength. This process is ideal for creating durable, lightweight components used in everything from construction and bridges to Infinity’s industry-leading window frames.
The Ultrex® Pultrusion Process Explained
Infinity from Marvin windows are made using a proprietary fiberglass pultrusion process that ensures superior strength and long-term performance. Fiberglass fibers are reinforced with thermosetting resins—materials that, once cured with heat, undergo a permanent chemical change. This makes the resulting window frame exceptionally strong, stable, and resistant to deformation. With Ultrex®, you get precision-formed fiberglass that stays true to shape and resists expanding and contracting over time.
Pultruded fiberglass is composed of glass fibers and durable resins. The process begins with finely ground raw materials—primarily Silica and Zirconia—melted at around 1500°C. The molten glass is drawn into ultra-fine filaments, bundled into strands, and heat-cured into rovings. These strands are then used to form the backbone of Infinity’s Ultrex® fiberglass—delivering exceptional longitudinal strength and rigidity to each window profile.
The resin used in Ultrex fiberglass is typically a high-performance polyester. This type of resin offers excellent strength, adhesion, and resistance to chemicals. During the pultrusion process, these resins are carefully blended with pigments and fillers to create a strong, stable matrix. The result is a low-maintenance, high-strength fiberglass frame that delivers exceptional performance in any climate—including Colorado’s extreme temperature swings.
Why Homeowners Trust Ultrex® Windows in Colorado
- Increased Strength: Fiberglass strands are processed under tension, delivering incredible tensile strength.
- High Fiber Content: A greater glass-to-resin ratio means improved structural integrity.
- Low Expansion: Ultrex® resists expanding and contracting with temperature changes—unlike vinyl.
- Consistent Quality: Pultrusion delivers uniform profiles with precise, repeatable performance.
With Infinity from Marvin’s Ultrex® fiberglass, you’re getting a window material engineered to perform in any condition—including Colorado’s unpredictable weather. At Gravina’s Window Center of Littleton®, our 50+ years of installation experience and commitment to excellence ensure your new windows are built to last and installed with precision. From start to finish, we’re here to help you choose the right solution for your home—backed by world-class craftsmanship and trusted performance.
Ready to upgrade to windows that actually perform? Explore Infinity from Marvin windows or schedule a free consultation today.
Award-Winning Legacy of Customer Satisfaction
Infinity from Marvin has a long-standing reputation for excellence—including top honors in past customer satisfaction studies. In 2019, Infinity earned the #1 ranking in the J.D. Power Windows and Patio Doors Satisfaction Study based on customer feedback in three key areas: appearance and design features, operational performance and durability, and warranty.
While the study was conducted several years ago, it remains a testament to Infinity’s commitment to quality and service—values we continue to uphold at Gravina’s Window Center of Littleton®.
“We’re not focused on being the biggest window and door replacement company — we’re focused on being the best.”
– Dan Marvin, President of Infinity from Marvin (2019)
Infinity earned a satisfaction score of 890 out of 1,000, based on feedback from 2,913 homeowners surveyed between January and May 2019.