How many cans of undercoating are generally needed?
4 Answers
Generally, about 5 cans of undercoating are needed. Below is some relevant information about undercoating: 1. Introduction to undercoating: The formal name of automotive undercoating is automotive chassis anti-collision, anti-rust, and soundproofing coating ("UNDERCOATING" primer), a high-tech adhesive rubber asphalt coating. It is non-toxic, has high coverage and adhesion, and can be sprayed on exposed parts of the vehicle such as the chassis, wheel hubs, fuel tank, lower panels, and trunk, forming a strong elastic protective layer after quick drying. 2. Functions of undercoating: Undercoating can effectively protect the chassis from road gravel impacts and prevent minor scrapes and friction; it prevents corrosion of the chassis metal plates by acids, alkalis, and salts; it prevents loosening of chassis screws; it reduces noise transmission during driving, enhancing driving quietness; and it blocks heat conduction from the chassis metal plates, keeping the cabin warm in winter and cool in summer.
When helping friends with this, I always mention that the number of bottles depends on the car model. For smaller cars like sedans, which have a smaller chassis, 4 to 5 bottles are usually enough. However, if your car is an SUV or off-road type with a larger and more complex chassis, you might need 6 to 8 bottles. The capacity of the bottles also matters—standard spray cans are about 400 milliliters per bottle. Applying undercoating isn’t just to protect against stone impacts; more importantly, it prevents corrosion and rust—metal parts of the chassis can rust easily in areas with heavy rainfall. It’s recommended to apply 2 to 3 even layers during spraying—too thin and it won’t work, too thick and it may crack. Also, make sure to thoroughly clean the chassis before spraying; I’ve seen people skip this step to save time, only for the coating to peel off faster. Beginners can opt for professional shops, as they measure the amount more accurately. In short, after spraying, check the drying status before driving out.
I've done DIY undercoating a few times. My compact car took exactly 4 spray cans to fully cover the undercarriage without issues. Each can typically covers about 1 square meter, but check the product specs. Always measure your undercarriage area before purchasing cans – running out mid-project is frustrating. The process itself is time-consuming, taking half a day. The advantages include cost savings and corrosion protection for your chassis. Long-term, skipping undercoating leads to part corrosion and costlier repairs. Avoid water contact for 24 hours post-application for proper adhesion. Choose rust-resistant products – water-based options are eco-friendly but may lack durability.
The number of bottles for undercoating mainly depends on the vehicle size. Small cars require about 4 bottles, while larger vehicles need 6 or more. Applying undercoating can effectively prevent rust and scratches. Without it, the chassis is prone to damage under harsh road conditions. A key factor is the coating thickness—it's recommended to apply evenly but not too thick. Beginners can start with a simple quantity estimate.
