Underbody Protection Sprays

Underbody Protection Spray for Corrosion & Stone-Chip Protection

Underbody protection spray is an aerosol coating designed for vehicle floors, wheel arches and other suitable lower body surfaces exposed to road debris, moisture and mechanical wear.

Depending on the formulation, these products can provide protection against corrosion, stone chips, moisture, road contamination and mechanical impact. Available technologies include bitumen-based, rubberised, textured and paintable coatings.

Not every underbody spray provides the same properties, so select the product according to the substrate, required finish and whether the coating will subsequently be painted.

Where Can Underbody Protection Spray Be Used?

Depending on the individual product, typical applications include:

• vehicle underbodies,
• wheel arches,
• outer sill areas,
• lower body panels,
• front and rear valance areas,
• local repairs to sound existing underbody coatings,
• other suitable surfaces exposed to stone impact.

Always check the approved substrate and preparation requirements for the individual coating.

Types of Underbody Protection Spray

Bitumen Underbody Spray

Bitumen underbody coatings are commonly used on lower vehicle areas exposed to weather, moisture and road contamination.

They can form a relatively thick and flexible protective layer, with some products also providing sound-damping properties.

Not all bitumen coatings can be overpainted, so check the technical specification before applying subsequent paint.

Rubberised Underbody Spray

Rubberised underbody spray can create a flexible coating for suitable underbody and stone-impact areas.

Mechanical, weather and chemical resistance varies between formulations and should always be checked for the individual product.

Paintable Underbody Protection

If the protective coating will later receive an automotive colour or other compatible topcoat, choose a product specifically described as paintable.

This type of coating is useful on sills, lower body sections and repairs where stone-chip protection needs to sit underneath the visible paint system.

Stone-Chip & Textured Coatings

Stone-chip coatings can form a flexible, textured finish designed to protect vulnerable lower body surfaces from mechanical impact.

They are commonly used on sills, valances, wheel arches and other suitable body sections.

Underbody Protection vs Cavity Protection

Underbody protection and cavity protection are different coating functions.

Underbody coatings protect exposed lower exterior surfaces, while cavity protection products are designed to penetrate enclosed body sections such as doors, sills and closed profiles.

Both systems can form part of a complete corrosion-protection process, but one does not automatically replace the other.

Aerosol vs Spray-Gun Underbody Coating

Aerosol underbody coatings are particularly convenient for local repairs and smaller areas because no compressor or dedicated application gun is required.

For a complete vehicle underbody or larger areas, bulk material applied with an appropriate spray gun may be more economical.

Can Underbody Protection Be Applied over Rust?

Underbody coating should not simply be used to cover loose or advanced corrosion.

Remove unstable rust, loose paint and poorly adhering existing coatings before preparing the substrate according to the selected coating system.

Severe corrosion or structural damage requires proper repair before protective coatings are applied.

Surface Preparation

• clean the surface thoroughly to remove mud and road contamination,
• remove grease, oil and other contaminants,
• remove loose corrosion and unstable coatings,
• sand or prepare the substrate where required,
• prime exposed metal if required by the selected system,
• allow the substrate to dry fully before coating.

Primer requirements vary between products, so always follow the individual technical data.

How to Apply Underbody Protection Spray

1. Prepare and clean the substrate.
2. Mask components that must remain coating-free.
3. Shake the aerosol thoroughly according to the instructions.
4. Carry out a test spray.
5. Apply the coating evenly at the recommended distance.
6. Observe the specified flash-off time between coats.
7. Allow the coating to dry correctly before use or overpainting.

Coat count, spray distance, drying time and overpaintability are product-specific.

Where Should Underbody Coating Not Be Applied?

Do not allow underbody coating onto safety-critical or functional components where it could interfere with operation.

This includes brake friction surfaces, unsuitable high-temperature exhaust components, moving mechanical parts, electrical connectors, sensors and drainage openings.

Inspect Underbody Protection Regularly

Protective coatings can be damaged by stone impact and mechanical wear. Periodically inspect wheel arches and exposed underbody areas and repair damaged coating where necessary.

Safe Use

Use aerosol underbody coatings according to the product label, technical data sheet and safety data sheet. Provide appropriate ventilation and use the specified respiratory, eye and skin protection.

Frequently Asked Questions About Underbody Protection Spray