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Decontamination Step-by-Step Guide

Decontamination Step-by-Step Guide

Decontamination refers to the process of removing contaminants that have bonded to your car’s paintwork. Contaminants can include particles of iron, tar, tree sap, etc.

These particles build up on the surface, making the paintwork look dull and hazy. As these contaminants cannot be removed through a normal safe wash process, they require specific products to break down the build up, to make for an easier removal.

This stage is especially important if you are going to be applying a layer of protection to the surface for a couple of reasons:

  • Contaminants reduce gloss and clarity of the paintwork, so it makes sense to have the paint looking as good as possible before locking it in with protection.
  • Typically, people will polish their cars to remove other defects that may be present. If a decontamination process is not carried out, then you run the risk of inflicting scratches and scores into the paint or damaging your polishing pad.
  • Ensuring your vehicle has a properly cleansed surface will help with the application of protective products such as ceramic coatings.
  • If your vehicle is already protected with a ceramic coating then the decontamination stage will help ‘unclog’ the coating and therefore help maintain its water repellent properties.

Chemical Vs Mechanical Decontamination

Chemical decontamination is the use of products that will have a chemical reaction with the embedded deposits. Whereas mechanical decontamination is the manual removal of any remaining particles. If you gently glide your hand over the panel, you will be able to feel if the surface has a rough texture, if so then you will want to carry out a mechanical decontamination using a good quality clay bar.

What you will need:

  • Power Washer
  • Iron Fallout Remover
  • Tar Gel
  • Clay Bar
  • Several Microfibre Cloths

How to: Step-by-step.

  • Start by carrying out your usual safe wash process and rinse well.
  • Spray the vehicle liberally with Iron remover and allow time to dwell, according to the product instructions. As the product reacts it will turn purple as it breaks down the iron particles.
  • Rinse off before moving onto Tar remover. Remember it is important to only work one panel at a time when it comes to Tar remover.
  • Spray the product on the lower position of the panel and allow a short dwell time so that the tar deposits start to run (check product instructions).
  • Taking a clean microfibre cloth, wipe away the tar particles, turning the cloth to a clean side as necessary.
  • When the vehicle is finished, give a thorough rinse with the power washer until any signs of water repellency have worn off. This ensures that the tar remover residue has been removed properly.

Moving onto the clay bar stage. Proper lubrication is key so you don’t inflict clay marring. There are a few options: clay lube, apply a layer of snow foam or mix water and Autobead Pure Shampoo in a spray bottle.

Top Tip: submerge the clay bar in warm water to make it easier to manipulate into shape.

  • Apply your choice of lubricant to both the vehicle and the clay.
  • Working top-down, move the clay bar across the panel in straight lines and avoid applying pressure through the clay.
  • Check the clay regularly and fold into itself when it has picked up any grit that would otherwise score the paintwork.
  • Remember if you drop the clay bar, do not reapply it to the car but rather get a new piece to avoid risk of inflicting damage to the vehicle.
  • Once you have completed the process around the entire vehicle you can give it a final rinse before moving onto the next stage of your detail.


  • How often should you carry out a decontamination wash?

    A decontamination wash should be carried out every 3 months.

  • When do you need to use a clay bar?

    Claying is an important stage of the decontamination process when you want to prep the vehicle for a coating. Therefore should it be carried out when you are planning on polishing the vehicle to remove any marring that may be left on the paintwork.

  • Which comes first, the tar or iron remover?
    This one is slightly controversial within the industry. Some detailers say tar first to reveal iron particles that may be underneath, while others say iron first so there are fewer abrasive particles on the paintwork when wiping away tar. In summary, find your own preference, as there is no real right or wrong here.
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