When millions of people see the structure, color and gloss retention are performance requirements, not finishing touches.
For architects, engineers and owners of stadiums, landmark bridges and signature canopies, the coating is judged by its color and gloss years after the ribbon cutting. A finish that fades or a repaint that cannot be scheduled around events becomes a public problem, not only a maintenance item.
This article covers how to write appearance into the specification, how color choice affects durability, how to use mock-ups, and how to plan maintenance access before the project is bid.
What Is a Weathering Performance Requirement?
A weathering performance requirement states, in measurable terms, how a finish is expected to hold its color and gloss under exterior exposure. It replaces a phrase like "match the approved color" with criteria tied to a recognized standard.
On high-visibility steel, appearance is a performance requirement. The specification should treat color and gloss retention with the same precision it applies to surface preparation and film thickness.
Weathering Standards: Writing Appearance Into the Specification
Specifiers have three commonly cited documents to draw from. Each was written for a specific purpose:
- SSPC Paint 36: A performance standard for weatherable two-component urethane topcoats, with several weathering performance levels whose requirements apply to white or light-colored finishes.
- SSPC Paint 47: A performance standard for field-applied fluoropolymer topcoats based on PVDF or FEVE resins, developed with bright and saturated colors in mind, with weathering shown by natural exposure or accelerated testing as agreed between specifier and manufacturer.
- AAMA 2605: A voluntary specification for superior performing organic coatings on aluminum extrusions and panels applied in a factory or on a coil line, useful for curtain wall and panel finishes and a useful comparison for color and gloss retention properties on field-applied coatings on structural steel.
Accelerated weathering results are best used to compare finishes, not to predict a service life. The HPC article What Is ASTM D4547 QUV Exposure Testing? explains how fluorescent UV testing works and what it can and cannot show.
Color Selection: How Color Choice Affects Durability
The color a design team selects affects how long the finish holds its appearance. Four considerations apply to most high-visibility projects:
- Saturated Colors: Field experience shows that bright reds, oranges, yellows and some blues, common in team and civic colors, fade more readily than neutrals because of the pigments needed to produce them.
- Color-Specific Data: Weathering data on the actual color, or the closest benchmark color, should be requested from the manufacturer before the color is final.
- Dark Colors: Dark finishes absorb more solar energy and reach higher surface temperatures, which is worth reviewing with the coating manufacturer for large exposed members.
- Precise Color Definition: The specification should name the manufacturer's color number or an approved drawdown, a gloss range, batch control, and touch-up material matched to the finish batch.
Gloss is a choice, not a default. Higher gloss finishes look sharp but show surface variation, weld marks and touch-up more readily, while satin or semi-gloss finishes are often more forgiving on large steel surfaces under strong lighting.
Mock-Ups: Seeing the Structure the Way the Public Will
For high-visibility steel, a color chip is not enough. A mock-up shows the combined result of surface preparation, fabrication quality, coating system and lighting.
An effective mock-up requirement includes:
- Representative Steel: The mock-up is applied to steel prepared and coated the way production steel will be.
- Real Viewing Conditions: It is viewed at public distances and angles, in daylight and under the project's architectural or event lighting.
- Written Approval: It is approved in writing and retained as the standard for acceptance.
- AESS Coordination: It aligns with the architecturally exposed structural steel (AESS) category set under the AISC Code of Standard Practice (ANSI/AISC 303-22), Section 10, which defines viewing distance and fabrication finish.
Maintenance Planning: Access, Cleaning and Records Before Bid
Every coating eventually needs cleaning, touch-up and later overcoating. On a stadium or landmark, the window for that work is narrow and access is expensive, so the time to plan for it is during design.
Owners and design teams should address these items before bid:
- Access: Lift locations, rigging points, catwalks and clearances, recognizing that event schedules and seasons will limit when work can happen.
- Cleaning: A periodic cleaning program, using methods the coating manufacturer approves, to remove dirt and deposits that dull the finish.
- Records: The coating system, product designations, color numbers and batch information recorded in the owner's operations and maintenance manual.
- Touch-Up and Attic Stock: Touch-up procedures for construction damage and attic stock of the finish color for early repairs, as described in Proper Methods for Touching Up High Performance Coatings.
- Overcoating: Documented manufacturer procedures for cleaning and overcoating the finish after years of weathering, so a future maintenance coat can be applied without full removal.
For an existing landmark being repainted, the condition of the current coating governs what is possible. Those conditions need to be verified in the field before a system is selected, and the HPC article Overcoating Versus Complete Removal covers that decision.
Tnemec Options: Finishes for Color and Gloss Retention
Tnemec Company offers finishes developed for exterior color and gloss retention. Tnemec Series 1072V Fluoronar, Tnemec Series 1071V Fluoronar, and Tnemec Series 1070V Fluoronar are advanced thermoset solution fluoropolymer finishes in satin, semi-gloss, and gloss.
Tnemec Series 1095 Endura-Shield is an aliphatic acrylic polyurethane finish.
As general guidance, a fluoropolymer finish is worth evaluating when:
- Color Is Saturated: The design calls for bright team or civic colors.
- Access Is Costly: Repainting requires major access equipment or event shutdowns.
- Intervals Must Be Long: The owner's goal is the longest practical time between repaints.
An aliphatic polyurethane finish is worth evaluating when:
- Color Is Neutral: The design uses whites, grays or other light colors.
- Access Is Manageable: The steel can be reached for maintenance without major disruption.
- Exposure Is Moderate: The structure is not in a severe coastal or industrial setting.
The HPC article Fluoropolymers or Polyurethanes: Making the Best Choice compares the two chemistries in more depth.
Conclusion
On a stadium or landmark, the finish has to hold its color and gloss for years, and the owner has to be able to maintain it. We recommend writing weathering performance into the specification using SSPC Paint 36 or SSPC Paint 47, confirming weathering data on the actual color, approving a mock-up under real lighting, and planning access and records before bid.
When the public sees the structure every day, the coating specification is part of the design.
Field Verification Before Specifying
The following conditions are to be confirmed in the field with the applicable test before a system is finalized:
- Existing coating condition and type on structures being repainted: visual assessment per SSPC-VIS guides and coating identification by lab analysis.
- Existing dry film thickness: SSPC-PA 2 using ASTM D7091 gauges.
- Adhesion of existing coatings: ASTM D3359 (tape) or ASTM D4541 (pull-off).
- Hazardous materials in existing coatings (lead, chromium, PCBs on older structures): lab analysis of samples.
- Compatibility of the proposed overcoat with the existing coating: test patch evaluated per ASTM D5064.
- Soluble salts on prepared steel near coastal or deicing-salt exposure: SSPC-Guide 15 field methods.
- Color and gloss of the approved mock-up versus production work: visual comparison under project lighting and gloss readings per ASTM D523.
We are happy to help. Contact a High Performance Coating Consultant in your region to review your project conditions and specification.