How Secco OS65 Steel Windows Are Made and Finished: A Practical Guide to Manufacturing Quality
What separates a beautiful steel window from a great one often comes down to the parts that rarely get discussed: manufacturing accuracy, surface preparation, and the finishing system. For architects and homeowners specifying slim-frame glazing, those details determine how long steel windows stay straight, smooth, corrosion-resistant, and visually refined.
Secco Sistemi OS65 is widely recognised for its ability to deliver elegant, Crittall-style sightlines alongside modern performance expectations. As a manufacturer of bespoke steel doors and steel windows, Portamet approaches OS65 projects with a focus on fabrication discipline and a finishing process designed for longevity—whether the destination is Poland, the United Kingdom, the United States, Canada, or the Middle East.
What Is Secco OS65?
Secco OS65 is a steel-framed glazing system engineered for slim profiles and architectural flexibility. It is commonly specified for residential renovations, commercial interiors, and high-end new builds where minimal frames and maximum glass are priorities.
OS65 supports a wide range of configurations, including fixed glazing, hinged openings, and large glazed screens. The system’s appeal lies in the balance between visual lightness and structural stability—particularly important in tall partitions or multi-pane compositions.
Manufacturing Secco OS65 Steel Windows: Key Stages
1) Technical Review and Bespoke Engineering
Steel windows are rarely “standard,” even when the aesthetic goal is consistent across a project. Openings vary, structural conditions differ, and performance requirements change depending on building type and climate zone.
Manufacturing typically begins with a technical review: final dimensions, operating types, sightline alignment, glass specification, hardware selection, and interface details with surrounding walls. For bespoke steel frames, this stage sets the foundation for clean reveals, consistent glazing bars, and predictable installation.
2) Profile Cutting and Preparation
Once drawings are approved, OS65 profiles are cut to size with tight tolerances. Clean, accurate cuts reduce the risk of misalignment at corners and intersections—critical for slim-frame glazing where even minor deviations become visible.
Preparation includes deburring and surface cleaning so that welded joints and coating systems can perform properly. Good preparation also supports crisp detailing where glazing beads, seals, and hardware must meet precisely.
3) Precision Welding and Frame Assembly
Steel windows depend on disciplined welding. Excess weld material can distort slender profiles; insufficient weld penetration can compromise strength. The goal is a stable frame that remains square, carries the glass safely, and preserves refined aesthetics.
After welding, joints are dressed and smoothed to achieve seamless transitions—especially important for interior screens and partitions where the finish is viewed at close range.
4) Hardware and Drainage Considerations
For opening lights, hardware choice influences user experience and long-term durability. Hinges, handles, locks, and restrictors must be compatible with the system and rated for sash size and weight.
Where relevant, detailing may include provisions for drainage and ventilation strategy within the system design. Careful planning here supports reliable operation and helps maintain the integrity of seals over time.
5) Glazing Preparation and Dry Assembly Checks
Before finishing, frames are commonly checked for squareness, sash clearances, and consistent gaps. Slim steel windows look best when sightlines are intentional and margins are even from panel to panel.
Dry assembly checks help ensure that glazing beads, seals, and accessory components fit correctly—reducing rework and supporting a cleaner final appearance.
Finishing Secco OS65 Steel Windows: What “Good” Looks Like
Finish quality is not only about colour. For steel doors and steel windows, the finishing process is a protective system that must resist corrosion, maintain adhesion over years, and stay visually consistent across frames, sashes, beads, and welded intersections.
1) Surface Preparation: The Hidden Determinant of Durability
The finish can only perform as well as the substrate beneath it. Effective surface preparation removes contaminants and creates the right conditions for coating adhesion.
Depending on project requirements and the selected finishing specification, preparation may involve thorough cleaning, mechanical abrasion, and other controlled processes to ensure a consistent surface profile. This is especially important around welded seams and ground joints, where coatings can be stressed.
2) Priming: Corrosion Protection Starts Here
A high-quality primer supports corrosion resistance and forms a stable base for the topcoat. Steel frames used in varied environments—coastal regions, humid interiors, or high-traffic commercial settings—benefit from a robust primer layer designed to protect edges, corners, and welded areas.
Priming also improves colour uniformity and helps reduce the risk of visible “mapping” at joints, where metalworking and heat can otherwise show through the finish.
3) Powder Coating vs. Wet Paint: Choosing the Right System
Two common finishing routes are powder coating and high-performance wet paint systems. The right choice depends on visual goals, durability expectations, and project context.
Powder coating
- Often selected for consistency, toughness, and efficiency.
- Provides a durable surface suitable for many residential and commercial applications.
- Available in a broad range of colours and sheen levels, including popular matt blacks and soft neutrals used in Crittall-style interiors.
Wet paint systems
- Often chosen where specific textures, heritage looks, or specialised performance specs are required.
- Can be advantageous for certain detailing goals, such as ultra-smooth finishes or project-specific coating systems.
Regardless of method, the key is process control: consistent film build, proper curing, and thorough coverage at edges and joints.
4) Attention to Corners, Glazing Beads, and Sightlines
OS65 is specified for slim profiles, meaning corners, glazing beads, and bars sit within the viewer’s focal range. A premium finish requires consistent coating thickness and uniform sheen across every component.
Well-finished glazing beads matter more than expected: they frame the glass, define the rhythm of the façade or partition, and influence how refined the installation looks from both near and far.
5) Colour Selection and Design Intent
Steel windows are often associated with classic black, but modern projects increasingly use off-black charcoals, warm greys, whites, and even muted greens or bronze-like tones. The chosen sheen level—matt, satin, or gloss—changes how light interacts with slim frames.
For design-led interiors, satin finishes can soften contrast while still emphasising the geometry of the steel. For bolder industrial schemes, a deep matt finish can reinforce the graphic lines of the glazing grid.
Performance Considerations: Slim Steel Profiles Without Compromise
Specifying Secco OS65 often involves balancing aesthetics with performance. Glass selection, seals, and manufacturing accuracy all contribute to the end result.
- Thermal efficiency: Modern steel window projects typically rely on appropriate glazing specifications and system design to support comfort and energy targets.
- Acoustic performance: The correct glass build-up can significantly improve sound reduction—particularly useful in urban homes and hospitality projects.
- Long-term operation: Accurate fabrication and compatible hardware help maintain smooth opening and closing across years of use.
As a manufacturer of bespoke steel frames, Portamet focuses on delivering slim sightlines alongside the practical requirements of contemporary buildings—ensuring the final installation looks minimal, performs reliably, and feels solid in daily use.
Specifying OS65: A Practical Checklist
- Define the aesthetic: sightlines, glazing bar layout, and finish sheen.
- Confirm performance targets: thermal, acoustic, and safety glazing needs.
- Choose the finish system: powder coat or wet paint based on context and expectations.
- Detail interfaces: tolerances, thresholds, handles, and adjoining materials.
- Plan logistics: lead time, installation sequence, and international delivery considerations.
Secco OS65 steel windows can look effortlessly minimal, but that simplicity is achieved through careful manufacturing and a disciplined finishing process. When each stage—from cutting and welding to priming and topcoat control—is handled with precision, slim-frame glazing delivers the refined lines designers want and the durability building owners need.
Portamet manufactures high-quality bespoke steel doors and windows in Gdańsk, combining European craftsmanship, custom-made production, and slim steel profiles for projects across Europe and beyond. Product exploration and quote requests can help align OS65 specifications with performance goals, finish preferences, and project timelines.