Coil Coatings, also known as pre-painted steel or pre-finished steel, are polymer coatings applied to steel or aluminum strip prior to fabrication. The metal is continuously coated in a roll-coating process and once dried, is coiled for storage and transport. This allows for large quantities of pre-painted metal to be easily handled, shipped and stored before use.
In the Coil Coatings process, the steel or aluminum strip is first cleaned and any oxide layers are removed. This prepares the surface for optimal paint adhesion. The strip then passes through a series of treatment tanks where it is exposed to chemical solutions that condition and enhance the surface. Phosphating is a common treatment that converts the metal surface into phosphate crystals, providing an anchoring layer for the paint.
After pretreatment, the strip enters the coating application zone where liquid paint is applied. Three common coating techniques used include roll coating, spray coating and curtain coating. Roll coating involves applying paint via a set of rolls, one of which is flooded with paint. This allows an extremely precise, uniform coat to be applied. Spray coating uses automated spray guns to apply the paint in a fine mist while curtain coating employs a 'curtain' of paint to coat the strip as it passes through. Once coated, the strip passes through curing ovens where air flow and infrared heat immediately cure and dry the paint. Cooling rolls then prepare the coated strip for coiling prior to shipping. Modern Coil Coatings facilities are fully automated, with line speeds commonly exceeding 100 feet per minute.
Advantages of Coil Coatings
Coil Coatings offer numerous advantages over field-applied finishes for building components. One of the primary benefits is improved durability and longer lifespan. The controlled application of multiple paint layers in a coil coater results in a thicker, more abrasion resistant finish compared to site-applied paints. Coil Coatings are formulated to withstand weathering and resist fading, chalking, peeling and cracks over many years with little maintenance required.
Another advantage is consistency. Coil coaters provide uniform paint thickness and an evenly cured finish across large surface areas. Unlike field application techniques, there is no risk of runs, sags or uneven drying that can impact the visual appearance or long-term performance. Any defects in the applied finish can be easily detected and the specific portion of strip recoated before use.
Superior corrosion protection is yet another advantage. Multiple paint layers, including a topcoat and primer optimized for the substrate, form an effective barrier against the elements. Independent testing has shown that Coil Coatings can last 2-3 times longer than site-applied finishes in corrosive environments before any red rust appears.
Sustainability is also a driving factor. By pre-coating long before construction projects even begin, on-site painting steps, materials and associated pollution/waste are eliminated. Transportation costs are lower too as pre-painted strip ships in a small footprint versus loose paint containers. Fast line speeds and automated processes make Coil Coatings one of the most resource-efficient industrial surface coating techniques available today.
Applications of Coil Coatings
Coil Coatings serve a diverse range of building product applications. They are overwhelmingly used for roofing and cladding in commercial, institutional and industrial construction. Most standing seam metal roofs today utilize pre-painted steel coil for its high-performance qualities. Metal sidings, gutters, downspouts, fascia and soffits are other common cladding uses.
In agricultural construction, pre-painted steel is ideal for barns, equipment shelters and fences due to its strength, durability and resistance to chemicals/manure. Coil coated aluminum finds application as facade panels on commercial buildings where a lighter gauge material is required. It's also widely used for signage panels, truck bed liners, utility enclosures, rain carrying products and anything else requiring a long-lasting, low maintenance coated finish.
The automotive industry makes extensive use of Coil Coatings too. Pre-painted steel strip offers the high-quality, scratch/chip resistant topcoats needed for vehicle bodies, while aluminum is often used for truck beds and equipment panels. Even in the construction of boats, RVs, transport trailers and pre-fabricated structures, Coil Coatings enable durable, uniformly coated components. Their versatility has helped drive widespread use of coated metals across multiple varied industries.
New Developments in Coil Coatings
In recent years, coil coating manufacturers have launched new product systems designed to meet evolving market demands. Pigmented polyvinylidene difluoride (PVDF) coatings are popular high-performance systems capable of replicating realistic wood and stone textures. They provide class-A automotive style finishes known for their scratch, impact and chemical resistance along with very long fade resistance.
Low-temperature curing or "low-bake" systems have emerged to address increasing environmental regulations on solvent emissions. By replacing traditional solvent-borne coatings with waterborne or 100% solid formulations, low-bake coatings can cure at temperatures as low as 250°F with very low VOCs released. Further advances involve nanotechnologies promising even higher levels of corrosion protection, self-cleaning, easy-to-clean and antimicrobial properties for coil coated materials. Coating suppliers continue optimizing products to meet strict performance standards and broaden coil coating applications into new market segments.
Since its origins in the 1930s, Coil Coatings technology has evolved tremendously to become a highly efficient, large-volume manufacturing process. It plays a vital role in advancing the building products and transportation industries by providing long-lasting, attractive and sustainable pre-finished components. Continuous research pushes the boundaries on protective and aesthetic performance while reducing environmental impacts. As construction and design trends demand higher-performing, lower maintenance exterior materials, Coil Coatings are well-positioned to answer this call and further cement their importance within industrial surface coating solutions.
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