Underbody Coating
UNDER-BODY COATING
Under-body coating is usually a dense cladding (often based on rubber) applied uniformly to the undercarriage of the automobile. It is normally sprayed or painted on when the car is just out of the dealership and is clean. But even if you are getting the undercoating applied after a couple of years, it’s fine too. This is because it can prevent further damage to the undercarriage.
Automotive coating process consist of following steps,
- Pre-treatment :
The first step in preparing BIW for subsequent coating is the pre-treatment process. Pre-treatment consists of cleaning the body surface to remove remaining oils from the stamping process and welding residues through three primary liquid dip processes of degreasing, conditioning and phosphating. The degreasing solution is composed of alkaline salts and surfactants and can include caustic soda, tri-sodium phosphate, and sodium carbonate. The surfactants are types of detergents for emulsifying oils and lubricants on the BIW.
- Electrodeposition(ED):
The metal underbody and frames of automobiles are coated to prevent corrosion, whereas other areas like the roof are not rust-proofed. When not coated to prevent corrosion, the structural metals (or other materials) are primed before applying additional coatings. The ED processes are modified as per the BIW material property. This ED coating provides rust and corrosion protection.
- Rust-proof materials:sealer/pvc
The third step is underbody coating (UBC) and seam sealing using PVC and urethane. The sealant is applied around and inside the doors, hood, trunk, and front dash and onto the exterior and interior of metal joints and outer area of the back wheel well.
- PRIMER:
The fourth coating step is the application of a primer surface or simply primer. It can be water-borne, solvent-borne or a powder. These primers are used to improve adhesion between the E-coat and topcoat, provide chipping protection, enhance paint appearance and also be environmentally compatible with emission regulations.
- Top-coat:
The final step in the body coating process is to apply the topcoat, which consists of two layers—the basecoat and clear coat. The basecoat contains the primary colouring pigment and the clear coat provides a protective coating against environmental effects, corrosion, and UV light degradation promotes unmatched colour retention and provides a smooth unblemished even finish.
TYPES OF UNDER-BODY COATING
Here are some of the various types of undercoating available.
- Rubberized undercoating
Rubberized vechicle undercoating easy to apply and offers sound-cushioning as well as protection from dust, moisture, and dings or dents.In addition to your undercarriage, rubberized undercoating is also safe to use on wheel wells and quarter panels, and dries to a soft rubbery finish that prevents further rust, damage, or moisture seeps. The coating can be painted over and, if necessary for bodywork, can be easily removed with an undercoating removal spray.Overall,Rubberized coating is generally the best option for protecting your vehicle's undercarriage, as it provides the simplest and best protective measures against rust and moisture.
2.Polyurethane Undercoating
The other option for undercoating your vehicle is to use a polyurethane-based sealant.This type of vehicle undercoating is a little bit quicker and easier to apply.Oftentimes, polyurethane undercoating will come in canister ready to preload into an application gun. This type of sealant works by seeping into all cracks and seams, displacing salt and moisture and oozing around rusty areas to bond with and protect unoxidized metal. It also sands quickly in case you'll need to perform bodywork and can be painted over.On the flipside, this type of car undercoating generally requires a little bit more surface prep work before applying - sanding and applying an etching primer to bare metals before using are generally recommended
3.Wax or paraffin-based undercoating
A paraffin-based undercoating will be the cheapest and quickest option available with which to protect the undercarriage of your vehicle. However, keep in mind that it will wear off quicker than other types of undercoating and will need to be stripped and reapplied at least once every year.Wax-based undercoatings never truly harden. During application, they drip or flow into seams and cracks to provide protective properties. They are usually available in a spray gun canister or in an aerosol can and offer at least a base protection in moderately humid climates.

4.Asphalt-based undercoating
For standard vehicles, any of the aforementioned types of undercoating will provide sufficient protection. For large trucks and heavy machinery, asphalt-based undercoating provides a bit of extra durability against rocks, chips, and moisture.Asphalt-based undercoating generally contains a little bit of rubberized material that sets up firmly and also helps soften noise. Generally sold in five gallon containers, this type of undercoating also needs more cure time than the other three, and is NOT paintable, making it best to use only for undercarriages.
UNDER-COATINS V/S RUST PROOFING
Rust is the enemy of any vehicle made of steel. If left unprotected it will inevitably win the battle and your vehicle will not be what it used to be.Rust proofing is done by spraying a protective wax all over the car and even into the car to protect hard to reach parts of the vehicle where moisture can accumulate. This has to be done on any part of the vehicle that is exposed to the elements and even on some parts of the interior of the vehicle as well.Some of these products can be used on the underside and chassis of the vehicle but most are designed to be used to protect the frame and the paint of the vehicle. There are a lot of these products on the market that can be used.
Undercoating is done by spraying an oil or a wax-based compound onto the entire underside of the vehicle and into hard to reach areas of the vehicle where moisture can get to. It creates a rust-proof layer that protects it from moisture and corrosion for about one year. In the case of Krown, it’s unique formula makes it self-healing so you will be protected throughout the course of the year.
ADVANTAGES OF UNDERCOATING
- FIGHTS RUST
It has a crucial function in preventing corrosion. Underbody coating is particularly useful if you live near the sea, where there is excessive humidity and rust is a common occurrence. If you live somewhere where it snows in the winter, you should seriously consider undercoating. During the monsoon season, cars are at high risk of getting corrosion. If you want to extend your car’s life you should get an underbody coating.
- ABSORB NOISE
Very strong undercoating, realize it or not, can attenuate noises that enter the cabin. The undercoating, which is frequently made of rubber, absorbs part of the rackets. The car’s occupants could avoid the road sounds — at least to some extent. So if you want a quite ride and pleasant experience it is always a good idea to consider getting an underbody coating.
- REINFORCEMRNT
If your automobile already has an underbody covering, applying another one on top of it will not harm it. It will provide further protection for the underbody from water, road debris, gravel, and tiny stones. The factory coat would also have a lower risk of flaking away.
- PROLONG CAR'S LIFE
A good undercoat protects not just the underbody from corrosion, but also the engine and gearbox! Less corrosion combined with slower wear and tear can extend the life of your car by many years. On the undercarriage, there would be fewer dents, dings, and scratches to worry about.
DISADVANTAGES OF UNDER-COATING
- Undercoating will not help you if corrosion already exists and the corrosion needs to be removed first before it can be applied, which can be expensive for you.
- It must be reapplied every 3 to 5 years for the best results
- When examining the vehicle undercoating pros and cons, you do want to look at potential downsides to getting undercoating.
- It adds weight to the vehicle.
- Undercoating will work best on new vehicles that have not been exposed to road conditions.