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What causes mold to grow on wall putty during the rainy season, and how can it be addressed?
Release time:
2026-01-29
During the rainy season, densely packed black spots quickly appear on the freshly applied putty on the walls. This happens because of high humidity and moist air, which easily cause the putty surface to become damp, thereby fostering the growth of harmful substances such as mold and bacteria. It’s not that there’s anything wrong with the quality of the putty itself!
During the rainy season, the freshly applied putty on the walls quickly developed dense black spots.
This is because the high humidity and moist air easily cause the putty surface to become damp, creating favorable conditions for the growth of mold, bacteria, and other harmful substances. It’s not that there’s anything wrong with the quality of the putty itself!
I. The Core Cause of Mold Growth:
1. During the rainy season, the air humidity is high (typically above 80%). If putty is applied to wall substrates that haven't dried completely (with a moisture content exceeding 10%), the moisture becomes trapped between the substrate and the putty layer, unable to evaporate in time. This creates a damp environment that fosters mold growth.
2. Failure to ventilate promptly after construction slows down the drying of the putty, leaving it in a damp and humid environment for an extended period, which promotes the rapid proliferation of mold.
3. Some wall surfaces (such as those adjacent to bathrooms or interior walls of balconies) have not been waterproofed, allowing rainwater to seep in during the rainy season and causing the putty layer to become damp and moldy.
4. After traditional alkaline putty powder deteriorates, its surface becomes porous and readily absorbs moisture, further exacerbating mold growth.
II. Corresponding solutions:
1. Pre-treatment for moisture prevention: Before applying the coating, ensure that the wall substrate is completely dry. During the rainy season, you can use dehumidifiers and fans to accelerate the drying process. Proceed with construction only after the substrate’s moisture content meets the specified standards.
2. Post-construction ventilation: After applying the putty, ensure adequate indoor ventilation and avoid keeping doors and windows tightly closed. If outdoor humidity is high, you can opt for brief ventilation during midday to minimize moisture infiltration.
3. Targeted Waterproofing: For walls prone to dampness, first apply a layer of waterproof primer, then smooth on a neutral putty from this product. Leveraging its waterproof and strong adhesion properties, this will effectively block moisture penetration.
4. Mold Treatment: For mild mold, first wipe off the mold with a dry cloth, then spray with a diluted solution of white vinegar. Let it sit for 10 minutes before wiping dry. After the wall has dried, apply an additional coat of this putty. For severe mold, remove the moldy putty layer, re-treat the substrate, apply waterproofing treatment, and then re-apply the putty.
5. Protection: Choose the neutral putty in this product, which has a fine texture and is resistant to crumbling. It effectively reduces moisture absorption and, when combined with subsequent coat of paint, forms a complete moisture-proof protective layer, significantly lowering the likelihood of mold growth during the rainy season.
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