Why Shouldn't the Putty Be Too Thick After Sheet Metal Repair?
2 Answers
If the putty is applied too thickly, it can lead to cracking after the car has been used for some time, causing the paint on the car body to peel off. Once the paint peels off, it can result in rusting of the car body, which may eventually lead to corrosion. More details are as follows: 1. Key Points: During sheet metal repair, applying putty is meant to level the surface, as the car body becomes uneven after repair. If the surface is not smooth, the final paint job will look poor and may also affect the adhesion of the paint. After applying the putty, it needs to be sanded before painting. 2. Recommendation: When performing sheet metal repair, choose a professional shop or go directly to a 4S store. Professional shops and 4S stores use high-quality putty that lasts longer. Non-professional shops often use low-quality putty, which tends to crack after a short period of use.
With over 20 years of experience in automotive sheet metal repair, I can confidently say that excessive body filler is absolutely a major taboo. It acts like a hard shell that tends to shrink, expand, and crack with temperature changes—especially during hot summers and cold winters. Even when the car is parked, cracks can appear. Thick filler also adheres poorly to metal, easily peeling off when driving over bumps, causing the painted surface to bubble and look unsightly. Worse yet, it masks underlying sheet metal issues, creating safety hazards in the event of a collision due to insufficient cushioning. I’ve seen many novices take shortcuts by applying thick layers to save time, only to end up redoing the work within six months, costing customers more in repeated repairs. The standard is to keep it under 3 millimeters—thin, multiple coats with proper sanding yield the most durable and worry-free results.
