FOCUS ON COIL PROCESSING
Steps on a modern coating line
■ Mechanical stitching of the strip to its predecessor.
■ Cleaning the strip.
■ Power brushing.
■ Surface treatment by chemical conversion.
■ Drying the strip.
■ Application of primer on one or both sides.
■ Passage through the first curing oven( between 15 to 60 seconds).
■ Cooling down the strip.
■ Coating the finish on one or both sides.
■ Passage through the second curing oven( between 15 to 60 seconds).
■ Cooling down to room temperature.
■ Rewinding of the coated coil.
The method includes cleaning and chemically pre-treating the metal surface. Before the final product is created, one or both sides of the metal are painted or coated with powders or liquids, which are then dried or bonded with plastic films. Coil coating employs processes such as cleaning; pre-treating; pre-priming’ pre-painting and coating flat metal coils of steel or aluminium. The coated metal coil is subsequently supplied to equipment manufacturers to be formed into a range of ready-painted parts.
Pretreatments are often used to help provide improved corrosion resistance of the substrate, often by passivating or converting the metal surface, typically via phosphate or chromate chemistries. The type of chemical treatment varies with the type of metal being used. Additionally, pretreatment can enhance performance of the fully coated product by adding topography to the metallic surface to help facilitate the bonding between the metal and the coating.
The continuous coil-coating process provides high standards of quality assurance through coil-to-coil consistency and has significantly lower environmental emissions than batch or post-painting processes. This reduces the need for re-work and lowers non-conformance levels and associated costs. By utilising prepainted metal in their process, manufacturers can also eliminate their paint lines which are usually the major bottleneck in their operation.
The market for coil coatings
Prepainted metals are widely used in many different applications and environments e. g. exterior and interior buildings, domestic appliances, furniture etc. Often used in construction, automotive and consumer goods’ sectors, prepainted metals offer durability and aesthetic flexibility. As demand for sustainable materials grows, the market continues to expand, meeting the evolving needs of modern industries.
According to a recent report by analyst Future Market Insights, the global market for coil coating is supported by increasing construction activity for architectural facades and roofing systems, the growing adoption of pre-finished metal products( reducing on-site painting requirements) and rising demand for durable and corrosion-resistant coatings across building envelope, transportation and appliance manufacturing applications.
“ Coil-coating manufacturers are expanding their production capabilities to address the growing demand for high-performance polyester and PVDF systems, textured and metallic finishes, and ecofriendly coating technologies for architectural and industrial metal substrate applications,” it said.
The growing adoption of circular economy principles in building materials and the proliferation of solar-reflective cool roof coatings will drive demand for coil coating products with enhanced sustainability credentials, superior weathering resistance and comprehensive performance documentation.
“ Between 2020 and 2025, the coil coatings market experienced steady growth, driven by increasing construction activity and growing recognition of coil-coated metal products as efficient alternatives to field-applied coatings offering superior finish quality, enhanced durability and reduced labour requirements,” said the analyst.
“ The market developed as architects and contractors recognized the potential for pre-finished metal to accelerate construction schedules, while delivering consistent appearance and long-term performance. Technological advancement in coating chemistry and application processes
Prepainted aluminium coil.
began focusing the critical importance of environmental compliance, colour retention and corrosion protection in modern building and industrial applications,” it added.
Market expansion is being supported by the increasing global construction activity for commercial, industrial and residential buildings requiring durable and aesthetically appealing metal cladding, roofing and building envelope systems that provide long-term weather protection, colour stability and lowmaintenance performance across diverse architectural applications.
The growing focus on environmental sustainability and regulatory compliance is driving demand for low-VOC and water-borne coil-coating formulations that reduce emissions during manufacturing and application while meeting stringent REACH, EPA and regional airquality regulations.
Flexibility in focus
There are different types of coil coatings such as anodizing, paint, liquid or powder coating. The coated surface can have a wide range of colours, gloss levels and surface textures. The end use of the finished product generally dictates the choice of coating. The user may require non-stick properties, great flexibility or high chemical resistance. Many new coating types are available to meet the increasing demands of users.
Prepainted aluminium, for example, is used in various ways to enhance the aesthetic appearance of public and commercial buildings. It also makes products more resistant to the corrosion caused by humidity e. g. in the marine environment.
Prepainted metals are also available with additional functionality included in the organic coating. Examples of this added functionality include anti-bacterial; anti-fingerprint; antidirt; easy-clean; non-stick and heat-reflective coatings. Advances in coating chemistry, such as pigment dispersion techniques and corrosion testing methods, have resulted in higher-performing coatings with improved coating application and quality control systems.
The global coil-coating industry continues to innovate, producing more flexible and versatile products to give added value to manufacturers now and in the future. n
Image: Haomei Aluminum.
ISMR December 2025 / January 2026 | ismr. net | 41