Underbody Coating

Underbody Coating

A car’s underbody is exposed to the most wear and tear caused by muddy water, potholed roads, stones and other obstacles on the road. Because it’s not in plain sight, we often do not see the damage.In Indian road conditions, a cars underbody is most prone to 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.

Process of undercoating

a) In manual Process the car is hoisted on a lift and the underbody is inspected for flaws and the under body is cleaned removing out the dirt and grease. Critical components like silencer are covered in a film to avoid the coating from sticking to it. Rest of the under body is spray painted evenly.The silencer film is removed and zinc coating is sprayed on it. Final inspection is done to look out for flaws. Nowadays this is performed by high speed robots that ensures a thorough coating on intricate positions.

Fig. Checking the underbody before coating

b) Another process is where the automobile frame is kept in a bath of liquid coat. The liquid in made to fall in a plent of amount and than the frame is allowed to get dry and the coat gets set on the frame.

c) Modern automotive coating methods consist of five main steps. They include the following:

1. Pretreatment: removes and cleans excess metal and forms an appropriate surface structure enabling bonding of a corrosion protection layer.

2. The next step is electrodeposition (ED) of the anti-corrosion or rust prevention layer.

3. A sealer like Poly Vinyl Chloride (PVC) is applied for anti-corrosion, elimination of water leaks, and minimization of chipping and vibrational noise.

4. A primer is then applied to promote adhesion between the surface and the basecoat; it also imparts a smoother surface for subsequent layers and has anti-chipping properties.

5. Finally, the topcoats that include a basecoat and clearcoat are applied; they provide surface properties that are sought after, including color, appearance, gloss, smoothness, and weather resistance

The areas of an automobile depicted in below figure shows where these five steps of coating and other additional coatings are used. As can be realized when examining this figure, a significant number of specific coating.

Types of undercoating

1) Rubberized Undercoating

Rubberized vehicle undercoating is easy to apply and offers sound-cushioning as well as protection from dust, moisture, and dings or dents.

In addition to 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 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 canisters 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.

Fig. Applying underbody sealant

3) Wax or Paraffin based undercoatings

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 fore mentioned 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.

Benefits of undercoating

• Minimizes Sound: It minimizes the sound from underneath the car resulting a noiseless, smooth driving experience.

• Heat Insulation: It insulates the interior of the car from extreme temperatures from beneath the vehicle providing a comfortable cabin experience.

• Anti-chipping property: If any stone hits the coating it does not get chipped away hence protects the underbody from exposure to water.