Anti rust / PVC Coating in Car underbody

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Its an open fact that underbody which is directly exposed to heavy mud and water should be protected properly aganist rust.

But there is only a thin film of sealant line in metal joineries and a spray of PVC in the inner wheel arches alone.

If u could see the truck cabins of AshokLeyland and Tata ,they have even better type of coating.

These are a thick layer of PVC sprayed directly in the underbody to a thickness of 150 - 200 microns.

This gives the following advantages:

1.Protection aganist rust and corrosion.

2.Protection aganist the stone chip off hitting the metal panels.

3.Additional protection to the thin layer of sealant applied on the metal joineries.


But these are sadly missed in our cars and we spend upto Rs.5000 for these type of coating.

With after market doing its duty in anti rust spray coat still we cannot go for PVC spray which gives better protection compared to thin film of anti rust coating measuring about 40 microns max.

Since this requires oven to bake after spraying and is not possible with dealers.


Last week I have seen a car in my ASC which was claimed to be coated with anti rust spray coat.The DFT was very less and mostly it was sprayed over the sand particles in the underbody without proper cleaning. Pre cleaning / Pre Treatment is very important before any kind of spray job but that was never done.With out proper tretament it hardly gives you any benefit.Dealer has charged around Rs.5000 for this job.



So I wish manufactures to look in this and sell the cars with proper underbody protective coatings.

Next, guys who do this in your car do take a look into car underbody for full application of coating with out any uncover and with proper coating thikness.A through visual inspection will yield good result before geting delivery of ur car.

Hope things work !!! 



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This kind of treatment isn't really needed for a new car. The metal that goes into making modern cars is pre-treated and don't rust easily.

New cars come with anti-rust warranties. So don't waste money on this unless you've scraped/dented your car's underbody.

Dealers only do it because it makes them a ton of money - its a total rip off.

The only cars that actually need underbody anti-rust treatments are Ambys, premier padmini's and other vehicles from that era.

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There is some more insight information about painting process.

The process wat u have mentioned is a regular Painting process. It stars from

1.Manual De oxidation,

2.Pre treatment,

3.Electro deposition - Baking


5.Sealant application

6.Primer application - Baking

7.Topcoat (2)- Baking

In this the first three process are dip process where the cabin will be dip inside the tanks during processing.Other processes are spray process so no access to underbody.Only sealant is applied in the underbody metal joineries.

I agree with you that they are subjected to salt spray test to with stand about 1000 hrs before getting rust.

But still there will be some problems in the coastal areas.

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If you do have a rusting/corrosion problem, why not ask the dealer about coverage under the manufacturer warranty first ?

I'm sure that the warranty would hold good unless the car suffers physical damage (accident repairs - welding, denting, etc. or underbody scrapes/hits from rocks).

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I got 3M under body coating and cavity protection done with a 5 year warranty for about 6 thousand rupees by the GM Chevrolet dealer.  I do live about 7 km from the ocean and drive for about 3 to 4 months on roads with pot holes full of water.  After spending about 11 lakhs for the Tavera, I didnot think that this is much for that peace of mind.


I had lot of tinkering done recently on my 2001 Santro.  I wish the original owner got the underbody coating and cavity protection when it was new for about 1000 bucks then.


I have a 2 year - 50000 km waranty on Tavera, but I purchased an additonal 2 year warranty for about 11500 rupees.  I may not need it- but, after spending 11 lakhs for this MUV, it didnot seem expensive.


 Any way, one needs to do cost benefit analysis to decide as to what is the right thing to do.  Some times the benefit may be just peace of mind.    



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Antirust coating was the rage across the globe in the 70's. We also put in Dunlop Rubbaseal as a routine, Since then manufacturers have come a long way and today unless you are in a very corrosion area (say right next to the sea) I would not bother.

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If your car has been repaired and weilded there is fair amount of chance that the car will catch rust, near the sea far more, however in new cars there is no need for this unecessary expenditure, as today car bodies are made on electroplated steel which is highly resistant to rust.

So no use unecessarily spending on these treatments and increasing the car weight.

I remember my dad got this under body tar based coating done on the AMBY because of which the car go good sound dreadning but paid the weight penalty.

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