Underbody Coating
UNDER BODY COATING :
Underbody coating is usually a dense cladding (often based on rubber) applied uniformly to the undercarriage of the automobile.
Underbody Coating is a sprayable coating, which protects the under surface of the vehicle from corrosion.
Underbody coating provides long term protection from corrosion to car's underbody. It also protects parts like internal body panels, frame rails and other inner cavities that are not physically accessible but are prone to corrosion.
Protecting the underbelly of the car should be our top priority. Especially during monsoon when heavy precipitation causes the roads to become mini-rivers and our cars are left stranded there. This makes them prone to heavy corrosion in the underbody region.
A car’s underbody is exposed the most to muddy terrains, potholes, debris and stones, and wet and even flooded roads that lead to corrosion of the underbody. Since the underbody is hard for us to inspect by ourselves, it is important to have an underbody coating in order to ensure your car is protected during these times.
In above picture we can clearly see how underbody coating has done.
THE UNDERBODY COATING PROCESS HAS 5 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
Rubberised Underbody Coating
Rubberized Undercoating produces a textured finish which resists chipping, abrasion, exterior rusting and weathering. Provides one-coat build-up with no dripping, running or sagging. It helps protect the undercarriage of cars, trucks, vans and recreational vehicles from both corrosion and abrasion. The coating may also be used to protect wheel wells, quarter panels, interior side of fenders, door skins, under side of the hood and trunk lid, floor pans, and more. The rubberized undercoating also helps deaden noise, allowing for a more pleasant and quieter ride. The spray goes on as a textured black finish that resists chipping, abrasion, exterior rusting, and weathering. It provides one-coat build-up with no dripping, running, or sagging. Protecting your vehicle with an application of rubberized undercoating is advised for long-term protection of the undercarriage. Rubberized undercoating creates a protective barrier that seals out grit, grime and moisture that could otherwise corrode the metal components. This extra protection is a low-cost measure that can pay off by potentially extending the service life of a vehicle.
Wax Based Underbody Coating
Wax Underbody Coating Spray is a solvent containing, bitumen free anticorrosive agent based on wax, polymers and anticorrosive additives. The product can be precision and exhibits excellent sag resistance. It is fast drying, and even in a thin layer thickness it forms a closed water protecting film. The dry film shows good adhesion and anticorrosive properties. Wax Underbody Coating Spray is primarily used on wax coated vehicle underbodies and particularly for the secondary treatment of all protective coatings, like those based on PVC, PVC/wax, bitumen/rubber and rubber/resins.
Polyurethane Under Bodycoating
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 a canister preloaded 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.
Asphalt Based Automotive Undercoating
Asphalt Based Undercoating does provide some benefits over Waxed Based Undercoating. They both stick well to most surfaces and do a great job sealing out moisture, road chemicals and oxygen. But mainly, Asphalt undercoating has the benefit of being less expensive. They protect anywhere up to 5 years and dry to a Firm to Hard coating.
Asphalt Based Undercoating does require a thicker film thickness meaning you will have to apply more product to the surface to be protected then if you use a Wax Based Undercoating. Additionally, Asphalt based products require more surface preparation because they can actually seal in rust and moisture allowing it to continue to grow. Finally, Asphalt based products continue to dry out over time causing cracks in the coating surface.
Advantages
Corrosive resistance
It plays an important role in keeping corrosion at bay. Underbody coating can come in handy especially near the sea, where there is too much humidity, and rusting is just one of those everyday things. Also it should be considered seriously a place where it snows in winter.
Noise Reduction
Very thick undercoating can soften the noises that reach the cabin. Since the undercoating is often made up of rubber it absorbs some of the rackets. The occupants of the car could spare themselves of the road noises, at least up to a certain extend.
Reinforcement
If the car comes with stock underbody coating, using another coating on top of it, is not going to hurt. It will offer additional reinforcement, protecting the underbody from water, road debris, gravel and small pebbles. There would also be a lesser chance for the factory coat to flake away.
Car life
Good undercoating not only defends the underbody from corrosion but also protects the engine and transmission as well! Less rusting coupled with slower wear and tear can surely add years to the lifespan of your vehicle.
Disadvantage
- Risk Of damage on moving parts during Application.
- A used vehicle may already have residue on the bottom of the car or even have spots of rust and corrosion. Undercoating will not help if corrosion already exists and the corrosion needs to be removed first before it can be applied, which can be expensive for the user.
Additional information:
NO - New car doesn't need an anti rust coating. It's one way for the dealer to squeeze money out of you.
This has become a regular norm in the industry now a days. Manufacturers do not ask customers to go for any anti rust coatings. The coatings i am speaking here is only applicable for underbody which is widely exposed to dust, dirt settlements, water and what not.
- Can be applied after 3years the vehicle is bought. Generally the vehicle bodycan withstand 5years minimum case. 3yrs I have considered because, cars in coastal areas are more prone to salt water and atmosphere also tends to initiate rust faster compared to other places.
- Your extended warranty of bumper to bumper covers it all. Then why should you spend additional 3000bucks for a damage that's not going to happen in the first place.