Can Soundproof Cotton Still Be Used After Getting Wet?
3 Answers
Soundproof cotton that has gotten wet needs to be replaced promptly. The ingress of water into the soundproof cotton may be due to poor vehicle sealing. Check the following aspects: 1. Aging sealing strips: Whether the sealing strips are aged, cracked, or incomplete, leading to poor sealing and water ingress. 2. Damaged waterproof membrane: Check if the waterproof membrane inside the rear door trim panel is damaged. Recall whether any repairs or modifications were previously done that might have affected the waterproof membrane. 3. Clogged drainage holes: Check if the drainage holes on both sides of the sunroof are clogged. If clogged, rainwater cannot drain through the pipes, causing the water level to rise continuously. When the water level reaches a certain height, it will flow along the headliner to the sealing strips and eventually onto the floor soundproof cotton.
I've been repairing cars for over a decade, and waterlogged sound insulation cotton is a common issue. Whether the cotton can still be used after getting wet depends on the extent of water exposure. If it's just slightly splashed with water, quickly remove it to air dry or use a hairdryer, then check if it still absorbs sound and blocks noise—if it works fine, you might get by with it. However, if it's severely soaked with water penetrating the core, it's basically ruined: it absorbs moisture, becomes heavier, affects the car's weight balance, and significantly reduces soundproofing performance. Worse, it can easily grow mold and bacteria, causing weird odors in the car, which is bad for the respiratory system over time and can corrode surrounding parts. I recommend car owners not skimp on this—if water gets in, disassemble it to check for mold spots and replace the cotton promptly to avoid future troubles. By the way, when washing the car, avoid using a high-pressure water jet directly on sensitive areas, and keeping door seals intact can prevent such issues.
Last year, my car was parked in the rain, and the sunroof leaked, soaking the soundproofing cotton. I tried to handle it myself by drying it with a towel and leaving it in the sun for a few days. The surface looked fine, but while driving, I always felt increased cabin noise and a musty smell. After asking a few friends, they all said it had to be replaced to avoid health risks. Eventually, I spent some money to have the shop replace the cotton, and the air immediately became much fresher. So, I think if it’s just a small splash, drying it might still work, but once the whole piece is soaked or develops an odor, it’s better to replace it without hesitation. Remember to park on higher ground to prevent flooding—simple habits can save you from big troubles.
