Aluminum Finishes for Architectural Applications
Karen Vetsch
May 2019

If left untreated, aluminum will corrode!  An ugly, whitish-gray powdery coating will appear (aka oxidation). And it’s not pretty. Aluminum warrants a proper finish. Finishes for architectural aluminum include mechanical, chemical, anodized, and organic coatings.



Mechanical finishes are processes that physically change the surface via grinding and polishing. Thus, aluminum applications with mechanical finishes are in storefronts and trim, wall corner guards, exterior panels, infill railings, handrail posts, etc. Mechanical finishes entail buffing, directional textured, non-directional textured, and patterned.

Buffing is the brightest mechanical finish as it creates a mirror reflectivity. Directional textured generates limited reflectivity but with a smooth, guiding, satin polish. Contrary, non-directional textured creates a matte finish of varying degrees of roughness through blasting. (Blasting method includes sand blasting, shot blasting, and glass-bead blasting.) Finally, patterned finishes are embossed or coined (sheet) metal. Embossing imprints both sides of the sheet aluminum, while coining refers to one sided stamping. Both typically require thin sheets.



Chemical finishes modify the surface of aluminum through one or more solutions. The main reasons for using a chemical finish, besides its cost effectiveness, are: to clean the surface to remove soils for a future finish; to prepare for anodizing (by producing an even electrochemical reactive surface); and to etch the surface to achieve a specific reflectivity. Etched chemical finishes on aluminum include matte finish, bright finish, and conversion coatings.

Matte finishes standards are fine matte, medium matte, and coarse matte. These etching treatments produce several degrees of mattes. Bright finishes are obtained by chemical brightening or electro polishing. Hence, chemical brightening treatments produce a high surface luster. Perfect for the fresh, shiny look!

Conversion coatings are used as the base for an organic coating. This is to prepare aluminum for coating (painting) or for an adhesive. However, conversion coatings are used as a post-treatment coating on other plating finishes, too.



Anodizing is a very common finish in aluminum finishes for architectural applications. It’s an electrochemical process that replicates naturally occurring oxidation by providing a protective “metallic” film on the aluminum surface. Anodic coatings include clear, color, integral color, brite dip, and electrolytically deposited. Classifications designate them as Architectural Class I Coatings and Architectural Class II Coatings.

Class I anodize coatings have a mil thickness of 0.7 (18 microns) or greater. This coating is a high performance anodic finish. Class I is in exterior building products and misc. metals. These products include guardrails, fences, perforated railings, rain screens, curtain wall panels, and other building facades.

Class II anodize coatings have a minimum mil thickness of 0.4 (10 microns). Class II is suitable for interior items not subject to excessive wear and tear, such as column covers, wall fins, and radiator covers. Additionally, Class II coating are great for light exterior applications, such as beam wraps, post wraps, storefronts and trim.



In the architectural industry, “coating” is the preferred terminology over the word “paint.” Painting is, therefore, reserved to imply house paint and automotive paint. The many ways to apply organic coatings include brushing, spraying, flow coating, and dipping. Popular architectural coatings for aluminum include resinous, vitreous and laminate.

Resin-based coating, PVDF, is a fluoropolymer resin; abbreviation for polyvinylidene difluoride. Available for liquid and powder coatings, PVDF resin-based architectural coatings provide high-performance durability. These coatings are common in curtain wall panels, metal roofing, metal cladding, and other building facades because of high durability and resistance to chalking.

Vitreous enamel, also called porcelain enamel, is generally classified as porcelain enamels and includes enamels and ceramics. This coating provides a glassy, smooth, hard coating. Vitreous coatings are excellent in elevated temperatures because of its wear resistance and thermal, plus electrical insulation.

Laminated aluminum is manufactured by bonding a polyester film to the aluminum. This plastic film is available in a multitude of colors and results in very durable protection layer. In addition, you see these in cladding panels and glazing systems, mainly for its uniform, flat color and texture appearance.



The main difference between liquid and powder coatings is the method of application. Equivalent paints are in both liquid and powder forms. Powder coating is a type of dry coating, while liquid coating goes on wet. For powder coating, electrostatically charged fine particles are first sprayed on aluminum, then cured under heat. This results in a remarkable thick coat with minimal or no paint running (unlike conventional liquid coatings).

The architectural market in the construction industry has recently taken notice of powder coating and its many benefits and advantages. Plus, powder coating is environmentally friendly! The process does not use solvents or harmful fumes, unlike traditional liquid coatings. It also produces a superior finish in extreme weathering conditions. Besides the unlimited color selection, there are plenty of textures to choose from. Powder coating is commonly used on perforated panels to get an even coat between and around the holes.



Specialty finishes, such as sublimation, mimic marble, granite, wood, custom designs, etc. You will see these on commercial and residential aluminum products. Thus, these aluminum products include pergolas, canopies, sunscreens, railings, windowpanes, cladding, etc. Sublimation is the phase transition of a substance from a solid directly to a gas without going through a liquid phase. This occurs under an exact temperature and precise pressure conditions. This specialty finish, for instance, imprints a pattern; much like a tattoo.



An appropriate aluminum finish not only looks attractive, but improves performance in strength and sustainability. The specifications, desired appearance and application decide the best type of aluminum finishes for architectural applications. Therefore, architects and specifiers base this on personal taste, eco-friendliness, performance criteria, and cost. Here at Astro, we consult on best finishes and coatings because we care.

Astro is a custom metal manufacturer. We have over 30 years’ experience in metal fabrication. Our core markets are Industrial Equipment/OEM’s and Architectural Metal Fabrication. Therefore, we are industry experts in both divisions and work primarily with stainless steel, aluminum, and Corten®. As always, if you have any questions, feel free to reach out to us. We love to help! Check us out online!


Aluminum Pergolas add Value!
Karen Vetsch
February 2019

Adding an eye-catching, well-designed pergola is an easy way to make a sophisticated upgrade to the exterior of any building. Certainly, architectural sunshades benefit many buildings in many ways. Astro’s aluminum pergolas add value by defining the outdoor living space, reduce your building’s energy consumption, and help you earn LEED® points.


Traditionally, pergolas have been made from wood or vinyl. For optimization, Astro recommends aluminum. For this reason, wood weathers with age and requires painting, staining or sealing every couple of years to protect it from fading, cracking and rotting. Similarly, vinyl can fade and crack, too. Aluminum, however, is lightweight, strong, resists corrosion, withstands high winds, offers a low maintenance finish, and is a highly recyclable material. Aluminum’s smooth, nonporous surface withstands weathering so it doesn’t require refinishing. Moreover, aluminum is typically fast and easy to fabricate and install for cost savings.



A pergola provides a welcoming spot for people to gather, while offering sun defense in the open-air. The feeling of being outside while being protected by heat and harmful rays is unparalleled to many, indeed. Besides, pergolas can be either attached to a building or stand alone. Pergolas not only have a dramatic impact on building appearance; they can dramatically affect indoor temperature as well. In fact, a carefully placed pergola can maximize solar heating in the winter and shading from the sun’s heat in the summer. Our project managers have the experience and expertise to consult the benefits a custom metal sunshade structure can offer. Whether we create a system to comply with your specifications, or produce original mockups from scratch, we can assist you in meeting LEED® requirements through a passive solar design.

Passive solar design optimizes building energy utilization by the engineering (or art) of shadowing. A shadow system (aka passive solar design) controls solar temperature influences in buildings, without the use of mechanical and electrical devices. Moreover, size and angle of shades are tailored to offer the best shading solution for your building. Innovative design options include cantilevers, curvatures, archways, etc. Thus, we do all this in accordance with sound engineering practices for complete support with wind, snow and ice loads. Aluminum pergolas add value in many ways.



A proper finish on aluminum improves performance in strength, sustainability, and aesthetics. Finishing options we recommend include: anodizing, PVDF coatings, powder coating, and custom finishes. Specialty finishes are now applied to mimic marble, granite, and natural wood. Yes, you read that correctly; aluminum is painted to resemble stone or wood! A nice wood-grain coating offers the traditional look of timber, but with all the added benefits of aluminum. These advantages include: resistance to rotting, scratches, chemicals, humidity, fire, and insects. Whatever finish you choose, aluminum pergolas add value with a lifetime of beauty to your construction project.



Architectural shading products come in all sorts of categories. Likewise, Astro has the ability to fabricate assortment of aluminum sunshades. These include:

  • Awnings
  • Canopies
  • Canopy Extensions
  • Canopy Trusses
  • Cantilevered Sunshades
  • Entrance Canopies
  • Extruded Sunshades
  • Louvered Roofs
  • Perforated Panels
  • Shade structures
  • Sundecks
  • Sunshade Bar Gratings
  • Trellis Screens
  • Verandas
  • Vertical Screens
  • Window Shades
  • Window Shades


Aluminum pergolas add value to buildings by providing a decorative element to the landscape. Therefore, pergolas and sunshade systems are ideal for any outdoor living space. Placement of pergolas include outdoor kitchens, swimming pools and spas, patios, terraces, courtyards, and gardens. In addition, they are picturesque for patrons everywhere. These are perfect, indeed, at libraries, shopping malls, theme parks, sports venues, country clubs, resorts, restaurants, apartments, hotels, parking tolls, and more.

We currently have our aluminum sunshade structures installed around the Midwest. For instance, these applications are in commercial-retail, government, airports, multi-residential buildings, and pedestrian bridges.



With the proper material, design, and installation, a pergola can last many years and remain practically maintenance-free. Consider Astro for designing your next pergola since our project managers and designers work diligently with you. In fact, we provide high quality, innovative solutions to ensure your sunshade structure will offer lasting beauty for many years to come. And remember, pergolas are more than a shading structure. They are a real living space that adds value to your commercial building! 

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Perforated Aluminum Balcony Railings
Karen Vetsch
October 2018

Many architects, designers, and contractors prefer perforated aluminum balcony railings for their guardrail system. Perforated aluminum combines a range of properties, including transparency, strength, rigidity, lightweight, and aesthetics. There are a variety of finishes, colors, and designs to consider when fabricating perforated aluminum balcony railings.


Why Perforated Aluminum Balcony Railings?

Consider perforated panels when weight, security, airflow, visibility, noise and aesthetics are imperative. Perforations can greatly reduce the weight of panels, but still offer a sense of security. These panels create a division of space for privacy, while still providing translucence. In addition to regulating ventilation, noise, shade, and visibility, perforated panels offer a modern aesthetic tone. Today’s perforated designs offer beautification while addressing growing concerns with privacy and security.


Why Aluminum?

Aluminum is most popular in perforated balcony railings because it is economical, lightweight, strong, and it naturally prevents rusting. Aluminum outperforms other materials because of its strength-to-weight ratio. Even though it is a third the weight of steel, it still hones very high strength. Besides being durable, aluminum is easy to clean, environmentally friendly, counteracts corrosion, resists abrasions, and has a long service life. This is especially important in climates prone to ice, snow and other wintery elements. This is because the strength in aluminum actually increases while retaining ductility in subzero temperatures.


What Design?

Depending on your provisions, Astro can provide a wide range of punched pattern formations. Whether you want simple or decorative, we offer an assortment of designs, style and patterns. Our sophisticated machines punch holes in sheet metal to transform it to exact specifications to perfectly customize your project. We offer standard straight-line designs as well as staggered. Accordingly, we can perforate varying size holes to give the look, feel and functionality you’re looking for.


What Other Applications?

Perforated aluminum panels are also used in staircases, stairwells, fences, gates, rain screens, grilles, acoustical wall panels, ceiling panels, wall facades, building envelopes, and more. They are chosen in public areas because of low maintenance and the prevention of accidental falls. These railings are standard in schools, factories, galleries, museums, libraries, apartments, condominiums, malls, parking garages, sporting arenas, etc.  As you can see, perforated metal panels have unlimited uses in unlimited places!


What Finishes?

A good finish improves performance in resisting corrosion, formability, and aesthetics in perforated aluminum balcony railings. Therefore, Astro recommends anodizing, 70% PVDF resin-based coatings, and powder coating.

Anodizing is an electrochemical process that replicates naturally occurring oxidation by providing a protective “metallic” film on the aluminum surface. An anodized finish increases resistance to corrosion, wear and tear. It is relatively inexpensive, non-toxic, chemically stable, and is heat-resistant to the melting point of aluminum. However, architectural anodize finishes are limited to certain colors.

High-performance 70% PVDF coatings (polyvinylidene fluoride), also known as Kynar 500®, is a resin-based liquid coating system. It has extreme weathering and chemical resistance, a high dielectric strength, and is non-reactive. It also retains its color over an extensive period of time. PVDF coating is common in curtain walls and building facades that need high durability and resistance to chalking. Not to mention, ultraviolet deterioration. This finish is typically more costly than anodizing, however, plentiful colors to choose from.

Powder Coating is a process when electrostatically charged powder is sprayed on aluminum, then cured under heat. This forms a remarkable coat.  This coat (or finish) is durable and is available in a wide variety of colors and textures. Powder coating produces almost no VOCs (Volatile Organic Compounds) and is considered environmentally safe. Plus, applying it doesn't create harmful fumes or contribute to air pollution.


Why Astro for Perforated Aluminum Balcony Railings?

Astro Engineering provides collaborative design in meeting performance specification and aesthetic objectives. We value a customer-centric approach with a defined schedule and set of deliverables. Our highly experienced project managers value continuous interaction with stakeholders in assisting your design. We look for ways for you to reduce costs while still meeting your specific needs. We also believe you will enjoy years of satisfaction and splendor with our high-quality perforated aluminum balcony railings!

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Rusty Trend: Weathering Steel in Architectural Metals
Karen Vetsch
August 2018

Weathering steel in architectural metals is a strong, durable, appealing metal material that hones self-healing abilities. With its rusty orange coloring and unique look, this is something you may have come across since this is so easy to recognize.

Weathering steel is a strong copper, nickel and chromium composite metal that embraces a rustic, countryside appearance. A rust-like oxide layer (or patina) develops nicely after exposure to the elements of weather. This surface layer of rust acts as a barrier and actually protects the steel from further corrosion. Copper is the element responsible for bonding the protective oxide layer to the metal and slowing down corrosion. Even though the low amount of carbon creates the toughness, the superior corrosion properties are based on the copper and nickel content.

Engineers and architects have taken notice of this amazing architectural metal as it adorns many well-known buildings and monuments. Many call weathering steel, corten or COR-TEN®. Furthermore, U.S. Steel Corporation trademarked this name. Its CORrosion resistance and TENsile strength provided the blended word to illustrates its basic powerful structure.


Applications of Weathering Steel in Architectural Metals

This attractive, nominal maintenance steel is seen in a variety of applications, including exposed steel structures. Thus, these include bridges, buildings, building façades, fences, edging, retaining walls, and architectural sculptures. The corrosion rate is so low that structures fabricated from weathering steel can achieve a 120 year design life.

Examples of Weathering Steel in custom architectural metals around the world include:

  • Barclays Center sports Arena by SHoP Architects (New York)
  • The Angel of the North by Antony Gormley (England)
  • Matsunoyama Natural Science Museum by Tezuka Architects (Japan)
  • Design Museum Holon by Ron Arad (Israel)
  • Broadcasting tower in Leeds Beckett University by Feilden Clegg Bradley (England)
  • Sant Pere Sacarrera Footbridge by Alfa Polaris (Spain)
  • New River Gorge Bridge by Michael Baker Company (West Virginia)


Benefits of Weathering Steel 

The protective rust coating continually changes and improves with age, eliminating the need for constant repainting and re-coating. As a result:

  • lower overall lifecycle costs (about 5% lower than conventional painted steel alternatives);
  • reduced inspection cycles (reduces the need for maintenance and cleaning);
  • improved safety;
  • streamlined construction;
  • no volatile organic compounds (VOC’s) released into the atmosphere; and
  • ideal for bridges and other structures where access is difficult or dangerous;

The thickness and weight is reduced drastically because the natural-looking hard scape provides greater yield strength than low carbon steel (or mild steel). Plus, weathering steel can withstand very high temperatures. Hence, it makes a good choice of metal for chimneys, flues, and high temperature ducting, as well as custom architectural metals.


Conditions of Weathering Steel

  •  Weathering steel must be exposed to the elements through constant aeration. To procure the corrosion protection oxide film, a continuous wet/dry cycling is essential.
  • There are environments where weathering steel should not be used, such as in the vicinity of chlorides. This is because the corrosion resistance is not capable of withstanding the conditions, like sea water (chlorides prevent the film from forming). Consequently, this can lead to premature failure.
  • Weathering steel must not have other substances applied to it (e.g. paint, wax, varnish) before the passivating protective oxide film has formed and grown.
  • Unless a special drainage is provided so rain can drain away, weathering steel must not be in direct contact with the ground. Consequently, runoff from the metal can stain adjacent surfaces, such as concrete.
  • The metal’s corrosion-resistance is not as great in salt air or when placed in constant contact with water.

Of course, with these fundamental conditions, weathering steel does not break or decay!


Brief History of Weathering Steel in Architectural Metals

Weathering steel was originally produced to eliminate the need for paint and maintenance on railcar wagons in 1933 by the US Steel Corp. Within a few decades, architects and engineers took interest of the unique reddish hue metal that employed amazing anti-corrosion and abrasion-resistance properties. By 1964, famous architect, Eero Saarinen, was one of the first to use the “earthy” weathering steel in architectural metals. Most noteworthy, Saarinen applied it to the interior and exterior façade of the John Deere World Headquarters building in Moline, Illinois. Today, weathering steel is in construction engineering, architecture, and of course, landscape design.


Contact Astro

This rusty trend in custom architectural metals is what’s hot! Our team at Astro is excited to start our next weathering steel project: perforated panels for a large parking ramp in Minneapolis. In fact, each perforated weathering steel panel will contain over 10,000 perforations in each panel! That's amazing!

Contact us today at to discover how we can assist you in making your next weathering steel (or any steel) project a smooth and cost-effective experience.

How to Work with Your Metal Fabricator
Karen Vetsch
July 2019

When you call Astro, your metal fabricator, expect friendly, personalized customer service. After gathering some basic information about your project, we ask for drawings, specs, sketches, and/or photos that you can email us. Next, an estimator may contact you to discuss any remaining details needed about the specifics of the project. These specifics include material type, gauge, tolerances, quantity, finish requirements, project schedule (timeframe), site conditions, type of project, and budget.


Ask About Our Capabilities

There are many different types of metal fabrication capabilities we offer.  Understanding your metal fabricator capabilities puts you and your company in the best position to win for the long term by saving time and money. Our Project Managers work together with you on the best methods and materials for producing your project. Therefore, we identify if there are alternatives that will make your project less expensive to fabricate.


Give us Clear Expectations

Communicate timelines early on. The more clear and explicit you are about your deadlines, the better, because it allows us to properly assign a realistic lead time. Perhaps you are early in project discovery and a budgetary quote. Often, a budgetary quote is put together very quickly to give you what you need for now. In addition, it's important to understand that low volume vs. high volume costs more. This is because of the time spent in estimating, drafting and setting up the equipment.


Provide Proper Drawings, Specifications, Sketches, and/ or Pictures

The more detailed information provided, the better we’re able to prepare you with a good proposal. Providing detailed information up front will ensure that the quotes are accurate based on the project parameters you require.  Precise and detailed communication establishes a great working relationship from the start. However, if you don’t have all the answers to these questions, we work collaboratively with you to find the answers needed for an effective quote.


Ask for Examples of Our Work

We are more than happy to provide you with projects or parts similar to the one you’re requesting a bid for. Our aim is to make you feel confident moving forward in the bidding process.  Further, do not hesitate to ask us for references from past and current customers. We welcome this due diligence. We also acknowledge every RFQ is unique to every job.


Quality Metal Fabricator

Our quality management system ensures valuable, detailed inspection of your product throughout production. Through our QMS, we improve processes, reduce waste, and lower cost. Our processes routinely evaluate appropriate quality standards to look for changes. Thus, we identify opportunities for improvement. This keeps Astro in the forefront of innovation.  

Whether you require small-scale orders or very large, Astro operates at the highest level of efficiency and quality. So, call us today at 763-777-8087 to discover how we can assist you in making your next job a smoo

Cable Railings Preserves Your View with a Modern Look
Karen Vetsch
July 2018

To achieve an unobstructed view with a fresh, up-to-date look, consider a cable railing system for your balcony, stairwells and walkways. Cable railings preserves your view with that hip, modern look. Plus, they are clean, neat and sophisticated. Not to mention, structurally sound, sustainable, and a great choice for that contemporary look that will impress!


Painted aluminum,  stainless steel, and galvanized steel are the most common metals used for the posts and top rails on cable railings. Our project managers are experienced at offering the best option in metal to be used for the specific application. Floor mounted posts or fascia/side mounted posts are two options. To maximize deck space, choose fascia mount posts. Options for posts include square tube and flat bar. Also, these can be accompanied with a wide array of top rail options for a fully-customized look.

Cable railing systems maintain easier snow removal than the traditional barriers and there’s virtually no requirement for periodic cleaning. These railings are much more bird-friendly than glass railing systems and are unique because of the sleek, modern look this railing style offers.


FastRailing is Astro Engineering & Manufacturing’s newest product currently being field tested. This is a minimalist cable railing system. It features a patented in-post fastening system for easy install and virtually invisible hardware. You can see them currently installed on balconies, decks and stairs. What’s the fully engineered, prefabricated system is available to you next summer!


Cable rails are recommended if the view is important. They are a cost-effective option, all while being low maintenance and sustainable. This is because there is less welding, less in-fill material, and an easy installation. Certainly, consider having a great view of the golf course, woods, mountains, city, lake, and kids playing in the back yard. Even transportation departments incorporate cable rails because unobstructed view it offers, plus safety.

Each job here has a dedicated project manager who works closely with the customer and the shop to ensure timely and accurate product deliveries. Indeed, our customer service awards testify to that! The knowledge and experience of our project managers provide problem solving and solutions to complex-scope projects others won’t do! Hence, contact Astro today for more information or to get a quote!

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