In this era where aesthetics matter, whether it's interior decoration or exterior wall renovation, we use architectural coatings to adorn and protect our walls, safeguarding the structure and enhancing its aesthetic appeal. However, it's not hard to notice that many buildings exhibit issues like cracking, discoloration, blistering, and peeling shortly after completion. These problems often result from subpar product quality or improper construction techniques. So, when faced with paint film cracking, how can you address and prevent these issues?

I. Causes of Exterior Wall Paint Cracking

1.      Cracking at the substrate level: The base layer for the exterior wall paint finish is a cement plaster, which undergoes shrinkage and temperature-related contraction during the curing process. If the exterior plastering is not done correctly, it can lead to hollow spaces and cracks. If repairs are not made before the paint layer application and the wall undergoes exposure to weather, the internal cracks will gradually extend outward. The thin paint film layer is not well-equipped to withstand this internal stress, resulting in cracking.

2.      Cracking in the putty layer: Cracking in the exterior wall putty layer can occur due to the use of low-quality putty with poor crack resistance or improper construction techniques. The shrinkage and cracking of the putty layer can affect the paint layer.

3.      Cracking in the paint film layer: Certain paints with quality issues or inadequate crack resistance, combined with improper application, can lead to problems such as cracking and other quality issues shortly after exposure to sunlight and weathering.

II. Prevention and Remedies (1) Material Selection

·         Cement for plastering: Avoid using fast-setting cement to prevent early cracking due to rapid cement mortar curing. Choose quality river sand with an appropriate particle size (not too fine) for plastering.

·         Choice of exterior wall putty: Preferably, use specialized anti-crack flexible putty products from reputable brands or large manufacturers after observing their performance over time.

·         Selection of exterior wall paint: Opt for thick, crack-resistant exterior wall paints like elastic textured paints, relief paints, or similar types. These paints have a thickness over five times that of regular paints, which can effectively resist the cracking caused by underlying cracks.

(2) Construction of Exterior Wall Mortar Layer

·         The mix ratio of cement mortar used for exterior plastering should be appropriate, with the right amount of cement. You can add fly ash or bonding agents to enhance the consistency and adhesion of the mortar.

·         Strictly adhere to the exterior plastering procedures and techniques. Clean the base surface of dust, dirt, oil stains, and earthen plaster on brick walls. Pre-wet the wall before construction and provide post-construction curing.

·         Enhance mortar crack resistance by using a method like attaching steel wire mesh at the junction of brick walls and concrete beams and columns.

(3) Construction of Exterior Wall Putty Layer

·         Apply the putty layer after the curing period for the plastering layer.

·         Inspect the plastering mortar layer before applying putty, rectifying any surface defects and cleaning off dust.

·         Follow construction specifications strictly, avoid working in direct sunlight, and keep the putty layer in a dry, shaded state.

·         After completing the putty layer grinding process, perform timely maintenance to keep the wall surface clean.

(4) Construction of Paint Film Layer

·         Use alkali-resistant primers before painting. Choose a primer with good anti-mold, anti-bacterial, and acid-alkali resistance to enhance the adhesion between the paint layer and the putty layer.

·         Avoid painting in high winds, rainy or foggy weather, or high humidity conditions to ensure a dry work surface. Try to avoid painting under intense sunlight or high-temperature conditions.

These recommendations can help you avoid exterior wall paint film cracking issues. Material selection, proper construction techniques, and thorough maintenance are all key factors to ensure the durability and aesthetics of exterior wall decoration. To guarantee the quality and longevity of exterior wall decoration, strict adherence to relevant standards and specifications, the use of high-quality materials, and thorough inspection and maintenance throughout the construction process are essential.