Professional Carwashing & Detailing

Removing cement from a vehicle's exterior

January 17, 2014

Jim Hammill, co-founder of the Professional Detailer Technicians Association (PDTA), answers a question submitted by an anonymous detail shop operator asking how to remove cement from a vehicle’s exterior.

Question: What’s the best way to remove cement from a vehicle’s outer surface?

Jim Hammill: Concrete splatter on the painted surface of a vehicle can be one of the most perplexing issues to deal with for a detailer or a carwash operator.

Although it is not impossible to remove, it is a lengthy process that cannot be hurried. There is no quick way to remove this product safely from the vehicle’s finish.

Read also: Rail dust and its removal

The trouble with concrete
Concrete consists of several ingredients that on their own are very damaging to a paint finish: gravel or crushed stone, cement and sand.

Once these ingredients are mixed with air and water they go through a chemical process known as “hydration.” The ingredients go from a liquid mass to a hardened mass.

This is why the procedure to remove concrete must be a chemical one and not a mechanical one. Any attempt to remove the concrete mechanically will result in permanent damage to the paint film.

Related: Detailing articles

The only way to safely remove the concrete then is to change the state of the concrete. Thankfully, there are now several products made by chemical suppliers that can do this and remove splatter without harming the operator or the paint film.

These products reverse the process and turn the concrete back into a liquid, where it can safely be washed from the paint film. Check with your local chemical supplier or search online to find one of these products.

The chemical solution
Even with these safer chemicals, there are still some risks, and detailers should:

  • Read the product MSDS sheet;
  • Wear the appropriate personal protective equipment; and
  • Follow the manufacturer’s instructions carefully.

Read also: The five factors of clean, Chemistry part 1

The trick is to let the chemical do the work it has been designed to do. It must be given time to work and soften the concrete to a state where it can safely be removed from the paint without scratching or causing further damage.

When a customer brings a vehicle in, explain to them that the process can take several hours and price the job accordingly.

Concrete splatter doesn’t just land on the paint, but also on the plastic trim and glass components of the vehicle. The same process must be followed on these components; the concrete must be softened to a state where it can safely be washed from the vehicle.

In the past many people used muriatic acid to do this.

The problem with using this acid is twofold: not only is it potentially harmful to the operator, but also to the new softer and more easily damaged clear coats on modern vehicles.

The acid may save you time, but the potential damage caused to the paint finish is irreversible.

Safety steps
Be sure to adhere to the following steps when removing concrete splatter:

Read also: The five factors of clean, Chemistry part 2

Step 1: Clean the car thoroughly before inspecting the paint film.

Step 2: Diagnose and identify contaminates, (concrete in this case).

Step 3: Use a chemical process to return the concrete to a liquid.

Step 4: Give the chemical time to work.

Step 5: Wash the splatter from the vehicle.

Step 6: Once the contaminant is removed, inspect the paint surface once more for cosmetic damage and repair as necessary, (polishing, waxing, etc.).

Following these steps will allow you to safely remove the concrete without damaging the paint surface.


Jim Hammill is the co-founder of the Professional Detailer Technicians Associa-tion (PDTA). He can be reached at