Underbody Coating
UNDERBODY COATINGS:
Underbody coatings are those which are used to prevent car bodies against rust and corrosion. This underbody coating helps in protection from dust and moisture also some other factors such as poor road conditions, rocks getting thrown from tires and denting the metal and salt from water during monsoon which plays an important role in damaging the underbelly of a car.
Modern automotive coating process:
The modern automotive coating consists of five steps:
- Pre-treatment its removes and cleans excess metal and forms an appropriate surface structure enabling bonding of a corrosion protection layer.
- The next step is electrodeposition (ED) of the anti-corrosion or rust prevention layer.
- A sealer like Poly Vinyl Chloride (PVC) is applied for anti-corrosion, elimination of water leaks, and minimization of chipping and vibrational noise.
- A primer is then applied to promote adhession between the surface and the basecoat, it also imports a smoother surface for subsequent layers and has anti-chipping properties.
- Finally, the topcoats that include a basecoat and clear coat are applied, they provide surface properties that are sought after, including colour, appearance, gloss, smoothness and weather resistance.
Pre-treatment:
The first step in preparing BIW for subsequent coating is the pre-treatment process. Pre-treatment comsists 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 fro 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 sealent is applied around and inside the doors, hood, truck, and front dash and into the exterior and interior of metal joints and outer area of the back wheel well.
Primer:
The fourth coating step in the applicantion of a primer surface or simply primer. It can be water-borne, solvent-borne or a powder. These primers are used to improve adhension between the E-coat and topcoat, provide chipping protection, enhance paint appearance and also be environmentally compatible with emmision 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 provodes a preotective coating against environmental effects, corrosion and UV light degradation promotes unmatched colour retention and provides a smooth unblemished even finish.
Different Types of Vehicle Undercoating
Having undercoating professionally applied to your vehicle can be expensive, but fortunately, if your budget is tight, you can do it yourself for a fraction of the price. Here are some of the various types of undercoating available.
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 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.
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.
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.
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.