How is the breathability of inorganic coatings?

I. Principles of Excellent Breathability

　　1. Porous Structure of Mineral Substrate

　　The main components of inorganic coatings are potassium silicate, silicate, and other mineral solutions. After drying, they form a honeycomb-like porous paint film through a silicon-oxygen bond crosslinking reaction. The diameter of these micropores is about 0.01–1 micron, smaller than liquid water molecules (about 100 microns) but larger than gaseous water molecules (water vapor molecule diameter is about 0.0004 microns), forming a "one-way breathing" structure:

　　Allows water vapor to permeate: Moisture from the wall base can evaporate into the air through the micropores, preventing stuffiness;

　Blocks liquid water from penetrating: External rainwater, condensation, etc., cannot penetrate the paint film, keeping the wall dry.

　　2. Chemical Bonding with Substrate

　　Inorganic coatings react with alkaline substrates such as cement and lime through chemical bonds, forming an integrated "coating-substrate" structure, rather than simply covering the surface like latex paint. This bonding method does not completely seal the substrate pores, but retains its natural breathability.

II. Practical Advantages of Breathability

　　1. Prevents Mold, Suitable for Humid Environments

　　In humid environments such as bathrooms, basements, and southern rainy seasons, wall moisture can be discharged through the paint film, reducing the conditions for mold growth (mold requires a humid environment to reproduce).

　　Case: After using inorganic coatings in a coastal residential area, the incidence of wall mold was reduced by more than 80% compared to traditional latex paint.

　　2. Regulates Indoor Humidity

　　The porous structure can absorb moisture from the air (such as humid air in summer) and release it when dry, providing a humidity buffer effect and improving living comfort.

　　Data: Laboratory tests show that inorganic coating walls can reduce the indoor humidity fluctuation range by 10%–15%.

　　3. Extends Substrate Lifespan

　　Avoids pulverization and hollowing of the base layer due to long-term dampness. For example, when inorganic coatings are used on exterior walls, the substrate moisture content can be maintained within a safe range (<8%) for a long time, reducing the risk of cracking.

　　4. Added Environmental Protection

　　Good breathability means that the wall is not easy to accumulate harmful gases (such as ammonia released by concrete). Coupled with the low VOC characteristics of inorganic coatings themselves, it further improves indoor air quality.

III. Comparison with Traditional Latex Paint

IV. Key Factors Affecting Breathability

　　1. Construction Process

　　If the base layer is not properly treated (such as the putty layer being too thick or dense), or the coating is applied too thickly, it may block the micropores and reduce breathability.

　　Correct method: Use thin-layer construction (single-layer thickness ≤0.1mm) and breathable putty (such as cement-based putty).

　　2. Coating Formulation

　　Low-end inorganic coatings, if too many film-forming aids or fillers are added, may damage the porous structure. It is recommended to choose products with **high silica content (silica-potassium ratio >1.5)**, such as Nippon QB series, German Mineral (MINERALO), etc.

　　3. Substrate Type

　　Suitable for alkaline substrates such as cement, lime, and gypsum. If used on non-alkaline surfaces such as metal and plastic, a primer (such as silane coupling agent) should be applied first, otherwise it may affect adhesion and breathability.

V. Recommended Application Scenarios

　　High-humidity areas: Bathrooms, kitchens, basements, swimming pool walls;

　　Exterior walls and areas with variable climates: Areas with frequent acid rain, areas with large diurnal temperature differences (such as Northwest China, plateaus);

　　Places with high requirements for environmental protection and comfort: Kindergartens, hospitals, nursing homes, etc.