Acktar Metal Velvet vs. Aeroglaze Z306 – Engineering Insights on the Blackest Black Coatings
Why Black Coatings Are More Than Just “Black”
In optics and aerospace applications, “black” is not a choice of color, it’s an engineering requirement. The world’s blackest coatings are developed especially to minimize stray light, scatter, and reflections in the most demanding applications:
- Space telescopes, trying to detect exoplanets a billion times dimmer than their host stars
- Semiconductor wafer inspection tools, looking for nanometer-scale defects
- Laser systems, where even small reflections can distort sensitive measurements
Vantablack, Carbon nanotubes, Aeroglaze paints, and Acktar coatings are all mentioned under the same domain, “black coatings,” but their performance under real test conditions differs significantly.
Aeroglaze Z306 vs Acktar Metal Velvet: A comparison of black coatings
At the University of Arizona, NASA-funded researchers used the Space Coronagraph Optical Bench (SCoOB) to test how different coatings limit achievable contrast.
| specular reflectance | diffuse reflectance |
Aeroglaze Z306 (a black polyurethane aerospace paint) | ~10⁻⁶ | ~4.8% |
Acktar Metal Velvet (a vacuum-deposited inorganic “blackest black” coating) | ~10⁻⁶ | ~1% |
The outcome was unambiguous: at narrow optical bandwidths, the Aeroglaze painted aperture stop dominated the contrast limit of the coronagraph, while the Acktar coated aperture stop contributed less than one-quarter of the scatter.
This brings a clear task for next Acktar developments
Blackest Black: Not All Coatings Are Equal
When used in membrane filtration setups, solutions like black paint or carbon nanotubes or black anodize is problematic. Acktar 100% nonorganic , biocompatible very thin black low reflection film help minimize the risk of contamination by providing a clean optical environment. This is essential for maintaining the integrity of the sample and avoiding false positives in detection assays.
Adaptability to Diverse Techniques
The term “blackest black coating” is often associated with Vantablack or other carbon nanotube based paints/coatings. Such blackening solutions achieve extraordinary absorptance in laboratory conditions, but they are fragile and difficult to integrate into real optical systems.
By contrast, Acktar’s Metal Velvet TM belongs to a different class: a robust, ultra-low reflectance black coating that can be applied directly to metals, ceramics and polymers, withstands vibration, and thermally stable from cryogenic to high-temperature (450 °C) environments. Unlike black paints such as Aeroglaze, Acktar coatings are:
– Inorganic and binder-free → no outgassing, UHV compatible
– Lambertian optical coating → truly diffuse, no sharp specular glints
– Mechanically stable → no flaking or particle release
In engineering terms, this makes Metal Velvet one of the most practical black coatings available today.
Future of Ultra-Black Coatings: Pushing Below Reflectance
Metal Velvet already delivers ~1% diffuse reflectance, placing it ahead of Aeroglaze and many other traditional coatings. But the demand for even darker, blacker coatings is inevitably growing.
Acktar is now developing the next generation of ultra-black coatings with <1% diffuse reflectance. This black optical coating under development will be suitable for aerospace optics, laser systems, and semiconductor inspection tools. This will give optical systems the same or even better performance than the darkest coatings out there, but in a form that is tough, clean, and ready to use in such applications.
Engineering Takeaway
The lesson is clear:
It can be detrimental for the project if one chooses the coating by an amorphic guess and not by empirical evidence. Not comprehending the difference between 1% and 5% diffuse reflectance can define the success of a billion-dollar space mission.
NASA’s SCoOB testbed have clearly demonstrated that the Aeroglaze Z306 paint has introduced five times more scatter than Acktar Metal Velvet has. In high-contrast optics, this is not a minor difference—it is the performance limit.
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References
- Ramya M. Anche et al., The Space Coronagraph Optical Bench (SCoOB): End-to-end numerical modeling of the testbed to estimate the contrast limits (2025). https://arxiv.org/abs/2509.02887
2. NASA, A Cryogenic Infrared Calibration Target: Characterization of Black Coatings (2014).
3. Europlanet EPN2020-RI, BRDF and Reflectance Database Report (2017).
The use of Acktar coatings yield major improvements in a wide range of products and applications.
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