The architectural coatings market
Unless you live and work in a cave, you probably spend much of your time surrounded by architectural coatings. All kidding aside, architectural coatings are everywhere in the built environment. The global architectural coatings market, currently valued at about 67.9 billion US dollars, is predicted to reach US $89.3 billion in value by 2027. This is a robust market with an estimated compound annual growth rate of 4.8%. Architectural coatings generally outperformed other coatings segments during the COVID-19 pandemic, providing a bright spot on the balance sheets of coatings manufacturers. Strength in the global construction sector, particularly in the Asia-Pacific region, is the main growth driver.
Formulating architectural coatings
There are unique requirements for architectural coatings compared to other markets. Architectural paints are the only coatings segment in which a significant portion of sales are to the do-it-yourself (DiY) end-user. The DiY factor requires formulation considerations related to price points, ease of application and marketing to diverse audiences not usually considered in automotive or industrial coatings. Substrate variability, environmental conditions during application, surface preparation and application methods are defined and controlled for most automotive and industrial coatings. This is not the case for architectural paints, especially those targeting the DiY market.
Architectural coatings can be organized into three broad groups based on function, substrate and the location within a structure they are used. These three groups are: primers, interior paints, and exterior paints. Each of these categories have unique performance expectations with accompanying formulation strategies. From basics like binder and extender selection to formula refinements including rheology modifiers and additives, function determines composition. Let’s review the requirements for these different types of paints and what raw materials are commonly utilized in each.
Primers
Primers form the foundation of any lasting paint job and are the key to successful topcoat application and endurance. Of course, primers need to fulfill their own set of customer expectations and formulations must be tailored accordingly. Adhesion to the substrate is most fundamental property requirement. Binders play the most important role in adhesion, but other components play roles. Other requirements for primers include filling a porous or uneven surface, blocking stains or contaminants from leaching out of the substrate, ease of sanding and short recoating time. Primers may be developed for use on a specific substrate, such as new drywall, or as “universal primers” suitable for a variety of surfaces.
Formulating primers requires a different set of raw materials than other architectural paints. Binders are chosen to adhere to the target substrate(s), dry quickly into hard easily sanded films and enable high loadings of extender pigments which helps fill porous surfaces. Extender pigment selection influences properties like stain blocking, sanding, recoating, flow, leveling and pore filling. Low oil absorption extender pigments allow high pigment to binder ratios at practical working viscosities aiding pore filling and smooth application.
Interior paints
Interior paints targeted to vertical wall (broad wall) applications makeup the largest sales volume of all architectural coatings’ markets. When you consider the amount of wall area inside your home, the variety of colors available and the fact that the segment has the largest DiY participation, this makes sense. Primarily paints for interior walls and trim in residential, commercial and institutional buildings, interior architectural coatings have differing requirements based on end use. Important properties for interior paints include coverage (hiding, leveling), sheen uniformity, color uniformity, scrub resistance, mar resistance, and adhesion to various substrates including wood, drywall, plaster and previously painted surfaces as well as primers.
It might not seem that interior architectural coatings have strenuous service conditions, but I ask you to consider everything expected of them. Formulations run the gamut from low-cost “contractor flat paints” meant for new construction tract housing to semi-gloss paints for demanding applications such as hospital and school corridors. Interior paint color in particular evokes strong emotions, from joy to loathing or even anxiety over color selection before and after the paint is applied to the wall. Flexible formulation strategies must be employed to develop lines of products meeting this broad range of customer needs.
Extender pigments are often overlooked in coatings formulation but they are very important to interior paint performance. Most of the key properties mentioned above are affected by the types and amounts of extenders. The type of extender used has a big impact on the price point, scrub and stain resistance, sheen value, sheen uniformity, volume solids and pigment volume concentration. Pigment volume concentration (PVC), defined as the volume of total pigment as a percentage of total volume of the solid paint film, is often very high in interior coatings relative to other coating types. Particle size distribution of extenders can also strongly influence opacity, tint strength, color acceptance and sheen uniformity of paints. Blends of extender pigments are often used to fine-tune these paint properties especially opacity and sheen uniformity.
Exterior paints
Even though not all building exteriors are painted, exterior paints are still a very important segment of the architectural coatings market. Exterior building materials like wood, fiber cement, composites, stucco or render, concrete (poured, pre-cast or blocks), and even brick are protected from weathering and enhanced in appearance by a coat of paint. Expectations for exterior architectural coatings vary with substrate base material, climate, type of construction and price-point. Among the properties required of exterior paints are resistance to efflorescence, alkali burnout, rain and moisture, surfactant leaching, UV Weathering, and dirt pick-up.
Climate, both macro and micro, has an outsized effect on the performance and longevity of exterior architectural coatings. Though some manufacturers take the approach that one exterior product line can achieve expectations of performance and durability for disparate geographies, regional paint companies succeed in the exterior coatings market by formulating products for specific climatic conditions. The most important formulation contributors to exterior paint performance are PVC, polymer binder composition and film hardness/flexibility balance. The binder polymer has more influence on properties in exterior coatings than primers or interior paints and should be the starting point in the formulation process.
The future of architectural coatings through the lens of recent developments
The future appears bright for architectural coatings, with strong predicted global market growth. Using recent trends and developments as a baseline, a few likely predictions for the near future can be made. Issues related to sustainability will gain importance. Sustainability is broadly defined as any product, process and regulatory or administrative action advancing one or more of the seventeen United Nations Sustainable Development Goals. Changes to architectural coatings formulations driven by a strengthening drive toward sustainability include the continued lowering and ultimate elimination of volatile organic compounds (VOC), reducing the risk of human exposure to hazardous chemicals and enabling a circular economy based on renewable resources. Waterborne coatings now dominate the global architectural coatings market moving the world closer to eliminating coatings as an air pollution source. Regulatory and consumer demand will increase the drive toward zero VOC eventually eliminating solvent-based coatings.
Both reducing VOCs and utilizing renewable raw materials address the sustainable goals of Climate Action and Sustainable Cities and Communities. Formulating architectural paints to facilitate reuse, repurposing and recycling of a building at the end of its lifecycle help enable the circular economy. This advances the previously mentioned goals as well as Responsible Consumption and Production, Life Below Water and Life on Land by reducing waste in landfills and our oceans. Architectural coatings with improved performance lengthen the time between repainting and help buildings last longer. Advanced paints of the future will increase building energy efficiency by reducing interior temperatures, insulating from heat or cold and protecting them from damage due to increasingly common extreme weather events. The evolution of architectural coatings continues to meet the challenges of the future.
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Excellent article !!
I like that you mentioned that exterior building materials of all kinds can be enhanced with a simple coat of paint. My city is planning on building a new theatre building and they are having the community help design it. I would love to suggest some of these tips to keep that building protected against the weather.