How to identify and choose thermal insulation coatings

Thermal-insulating coatings are a type of paint that has been developed in recent years, and their use has become remarkably widespread. With the increasing application of such coatings in residential construction, the market today offers a wide variety of thermal-insulating paint products. Even some industry professionals, however, struggle to distinguish between genuine, high-quality coatings and inferior or counterfeit ones—yet the establishment of clear criteria for evaluating these coatings often involves input from leading brands. So, let’s take a look at what aspects should be considered when assessing thermal-insulating coatings and how to choose the right product for your needs.

Types of Thermal Insulation Coatings

1. Barrier-type thermal insulation coatings. This type of coating primarily achieves its thermal insulation function through the coating’s inherent high thermal resistance and is classified as a thick-film coating. The typical application thickness for barrier-type thermal insulation coatings is 5–20 mm. Once nearly dry, these coatings exhibit very low thermal conductivity, effectively reducing heat transfer. However, they have a high water absorption rate, significant drying shrinkage, poor adhesion to masonry substrates, and limited decorative appeal. Consequently, such coatings are rarely used for interior wall applications.

2. Light-reflective thermal-insulation coatings. Also known as solar-thermal-reflective coatings, these formulations are characterized by the incorporation of hollow glass microspheres or ceramic microspheres, along with resins, metals, and fillers. After application, they form a coating with high reflectivity that effectively reflects sunlight, thereby achieving thermal insulation. The underlying insulation mechanism relies on high thermal reflectance to reduce heat transfer via electromagnetic radiation. In addition to thermal insulation, these coatings offer decorative benefits, self-cleaning properties, and the ability to repair cracks, making them a new generation of durable, energy-saving, and temperature-regulating coatings. When applied to building surfaces, they enhance thermal performance, reduce the energy consumption of air-conditioning systems, and thus contribute to overall energy conservation.

3. Radiative thermal insulation coatings. These coatings primarily function by emitting absorbed light and heat from buildings into the atmosphere in the form of electromagnetic radiation at specific wavelengths, thereby impeding heat transfer and achieving energy-saving and thermal-insulating effects. In addition to their radiative cooling performance, such coatings also offer advantages such as corrosion resistance, self-cleaning properties, and electrical insulation, while being relatively simple to apply. They are commonly used for interior and exterior wall finishes to help maintain stable indoor temperatures.

Identifying Thermal Insulation Coatings

1) Thermal insulation performance. Take two galvanized roof tiles, apply thermal insulation paint to one of them, and affix an alcohol-based temperature indicator strip to the underside of that tile using adhesive tape. Then place both tiles in direct sunlight and, after a short period, measure the temperature difference between the two. If the temperature difference between the two tiles is substantial, it indicates that the thermal insulation paint has poor insulating performance. Conversely, if the temperature difference is minimal, it suggests that the paint’s insulating performance is very poor.

2) Washability. Apply an insulating coating to a galvanized tile, allow it to dry naturally, then immerse the tile in clean water and scrub it for 30 minutes. Repeatedly rub the coated surface with your hand; if scratches appear and the underlying substrate is exposed, this indicates poor washability of the insulating coating. If the coating’s surface remains intact and no white, paste-like residue forms, this suggests that the coating has limited brush resistance and is of relatively poor quality.