Is Automotive Alloy Putty Really Crack-Free?
2 Answers
Not necessarily. To achieve a smooth finish in automotive paint sanding putty, it's essential to apply the putty evenly during the application process. This ensures faster sanding and better results. Additional reference materials are as follows: 1. Selection principles for putty application: There are various types of putty with different functions, and the compatibility requirements of coating materials make the selection of putty even more crucial. The compatibility issue between putty, primer, and topcoat is essentially a matching problem. Generally speaking, materials with greater polarity have stronger molecular bonding forces, whereas those with smaller polarity have weaker molecular bonding forces. Among them, synthetic resin coatings (such as amino and epoxy primers, putties, topcoats, etc.) have high polarity, while oil-based coatings (such as alkyd, phenolic primers, putties, topcoats, etc.) have low polarity. There is also another type of coating (such as alkyd primers, putties, topcoats, etc.) with polarity falling between the former two. 2. The selection principle for putty is: Consider compatibility based on the polarity of the coating. Generally, the polarity among primer, putty, and topcoat should be similar or relatively similar to ensure reliable adhesion and interlayer bonding strength.
I used to drive an old car with scratches on the body, which I repaired with alloy filler. I thought it would be fine as long as it didn't crack, but it still developed slight cracks during the summer heat. I consulted a car repair friend who said that alloy filler indeed has better crack resistance than traditional filler because it contains some alloy materials to enhance flexibility and prevent shrinkage. But completely crack-free? That's unlikely. Large temperature and humidity changes, especially winter freeze cracks in the north and rust from humidity in the south, can all cause issues. The application process is also crucial—if the surface isn't properly sanded or the primer isn't evenly applied, the filler won't bond well and is prone to cracking. It's recommended to choose reputable brands; although more expensive, their quality is more reliable. Avoid working in the rain during repairs, and allow at least two days for proper curing to significantly reduce the chance of cracks. While driving, try to minimize bumps and regularly wax the car paint to extend the filler's lifespan. In short, while crack resistance has improved, it's not a maintenance-free miracle—don't expect it to never crack. Proper use is key.
