Underbody Coating

Underbody Coating:

• Underbody Coating is applied on Vehicles to prevent the underbody surface from damages occuring due to Rain water, Mud, Slush, Snow, Gravels and stones.
• Damages ranging from Paint layer chip off to heavy Corrosion can occur on the Under Body of the Vehicle.
• The coating is a layer of defined thickness applied as a spray or a polish layer.
• This coating protects the underbody layer as well as parts like internal body panels, frame rails and other inner cavities that are not physically accessible but are prone to corrosion.
• During Monsoon or in a region prone to heavy snowfalls, the water/snow tend to cause heavy corrosion to the underbody as sometimes the water may stand due to poor drainage in the locality or in case of a flood.

Figure1: Application of Underbody Coating on a Car

Importance of Underbody Coating for a Vehicle:

• Protects Against Rust & Corrosion

  • The primary objective of underbody coating is to prevent metal components that are exposed on the bottom side of the car from corrosion damage.

  • The Adverse effects of corrosion on a vehicele can be eliminated by simply applying a rubberised anti-rust coating all over the belly of the vehicle.

• Reduces NVH (Noise Vibrations Harshness) Levels

  • Indian roads generally have uneven patches and potholes and while manoeuvring cars through such sections, the unpaved crumbs, and pebbles hit the car from underneath or get stuck in the wheel wells.

  • The underbody coating’s consistency is so thick that the layer it creates absorbs all the unpleasant noises and vibrations and marginally improves the driving experience decreasing some amount of NVH.

• Prevents Paint Chipping

  • Running on the highway or while pacing through a city road, the vehicle often encounters sharp gravel or any other unattended object hitting the belly of the vehicle with high momentum.

  • This scrapes and chips off the metal from down below.

  • A thick layer of Underbody Coating definitely comes to aid and minimises the effects of such contacts on the body.

• Protects Vital Components

  • Underneath a car is somewhere a lot of indispensable parts of a car are left exposed like the Engine, silencer, etc.

  • One simply can’t afford to let these parts go bad due to rusting and hence in order to be safe from a hefty repair bill, a considerably less expensive Anti-Rust Coating is a must.

Disadvantages of Underbody Coating for a Vehicle:

• Cost of Coating
  • A single visit to a service center for Underbody coating is quite expensive and also depends on the type of the vehicle. It is comparitively less costly for a hatchback and the cost increases as per the vehicle size and the amount of coating used.

• Coating Process Duration and Difficulty:
  • The process of Coating is a long and tedious process as the under body rusts need to be removed completely by saning or sand blasting process, then the underbody needs to be rinsed and dried properly.
  • After this process the underbody coating layer is applied and the coat layer may range from 2-3.
  • Then the rest parts such as the Exhaust pipes and the engine belly needs to be coated using Zinc mixture as these parts often undergo high temperature changes.
  • This process certainly requires skilled person.

• Life of Coat:
  • Some type of coatings such as Wax based have very less when compared to other coat types with life averaging 0.5-1 year.

Figure2: Underbody Coating on a bare metal of a Car

Types of Underbody Coating:

• Rubberized Coating

  • Rubberized Vehicle Underbody coating is easy to apply and offers sound-cushioning as well as protection from dust, moisture, and dings or dents.
  • In addition to the 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, this is generally the best option for protecting a vehicle's undercarriage, as it provides the simplest and best protective measures against rust and moisture.

Figure3: Rubberized Underbody Coating. Source: Youtube channel - Eastwood Company

• PolyUrathane - PVC Coating
  • This type of vehicle undercoating is a little bit quicker and easier to apply.
  • Often times, 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 a 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.

Figure4: PU-PVC Underbody Coating Layers. Source: Research Gate- publication: 332442857_Review_on_Automotive_Body_Coating_Process.

• Wax or Paraffin based Undercoatings
  • A paraffin-based undercoating will be the cheapest and quickest option available with which to protect the undercarriage of a vehicle.
  • However, 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.

Figure5: Wax Based Underbody Coating. Source: Kamebo.com

• 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 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.

Figure6: Asphalt based Underbody Coating. Source:https://www.flickr.com/photos/chocolatedisco/3366704034

Some Well Known Manufacturers/ Vendors of Underbody Coatings are:

• 3M
• Elvi Bardahl
• LiquiMoly
• Horizon
• Wuerth