Cracking and whitening are among the most common problems found after applying JS waterproof coatings. Many people immediately assume that the material quality is poor, but in reality, most waterproof failures are not caused by a single factor. The real causes are usually related to substrate condition, formulation design, construction methods, and environmental conditions working together. In many projects, inadequate substrate preparation, humid construction environments, or excessive water addition during mixing can significantly increase the risk of cracking, whitening, and even long-term leakage problems. Therefore, the key to solving JS waterproof coating issues is first identifying the type of problem and then optimizing both the material system and construction process accordingly.

Cracking in JS waterproof systems is generally divided into three types: irregular surface cracking, long straight cracks, and corner cracks. Irregular surface cracking is commonly caused by excessive shrinkage during curing, usually due to highly absorbent substrates, rapid moisture loss, or improper formulation ratios. For example, dry substrates can quickly absorb water from the coating, leading to rapid shrinkage, while dust or standing water on the substrate weakens adhesion and affects bonding performance. In addition, excessive cement content, low emulsion solid content, or poor-quality emulsions can significantly reduce coating flexibility and crack resistance. Long straight cracks are more closely related to substrate instability, such as cracked cement screeds, hollow substrates, or structural settlement. Once the substrate moves, the waterproof layer is pulled apart as well. Corner cracks are also very common because coating materials tend to accumulate around corners and pipe roots, causing uneven drying between the surface and inner layers, which eventually creates shrinkage stress and cracking.

To prevent these problems, proper substrate preparation and optimized formulation systems are essential. Before application, the substrate should be thoroughly cleaned and pre-wetted to a damp condition without standing water. During construction, the mixing ratio should strictly follow manufacturer recommendations, and excessive water addition should be avoided. Applying the coating in multiple thin layers instead of one thick layer can effectively reduce shrinkage stress. For corners and pipe root areas, rounded corner treatment combined with reinforcing fabric systems is strongly recommended to improve stress distribution and reduce cracking risk. As for whitening problems, they are mostly related to moisture migration, premature water exposure, or cement efflorescence. High humidity, poor ventilation, or water testing before full curing can easily cause surface whitening. Therefore, construction should ideally be carried out in well-ventilated environments with moderate humidity, while high-quality emulsion systems should be selected to improve coating density and water resistance. Only by combining proper substrate treatment, material quality, formulation balance, and construction control can the long-term durability and stability of JS waterproof coatings be effectively improved.