Automotive Sealants: Choosing & Applying for Car Bodywork
Automotive Sealants: Essential for Vehicle Repair
Sealants are crucial for ensuring the quality of vehicle repairs and maintaining anti-corrosion warranties. They serve various roles, including anti-gravel protection and soundproofing for wheel wells, floors, and other areas.
Types of Automotive Sealants
Extrudable Joint Sealants
Used when working with sheet metal, applied to all joints or seams. Application is typically done using a polyurethane cartridge with a manual or pneumatic gun. Polyurethane sealants have a high solids content and remain flexible. Drying occurs within 24 hours due to humidity.
Features:
- Excellent adhesion
- Does not deform
- Lightweight applications
Butyl Sealant
Another type of sealant, butyl, is sold in black and gray cartridges and is flammable. It seals internal and external joints over 3mm.
Features:
- Good adhesion to metal and painted surfaces
- Air-dries
- Water-resistant
Brushable Sealants
Ideal for sealing joints between different pieces, reproducing the original finish.
Features:
- Easy to apply
- No cracks
- Fast-drying
- Resistant to water, oil, and gasoline
Two-Component Sprayable Polyurethane Sealants
Reproduces the original finish of a sealant and anti-gravel coating.
Features:
- Components are mixed inside the container, ensuring exact proportions.
- Avoids isocyanate emissions.
- Application is simple, fast, and clean.
- Mainly applied in engine compartments.
- Seals resist heat sag.
- Available in gray.
Two-Component Sealant (Isocyanate-Free)
Another polyurethane-based sealant that does not contain isocyanate. It can be extruded and pulverized.
Features:
- Very low solvent content
- Easy to adjust
- Fast curing
Universal Sealant
An isocyanate-free sealant that can be extruded and pulverized to replicate all types of finishes. Its fast curing allows for quick application on repaired parts.
Weldable Sealant
Applied by brush, this sealant is an excellent conductor of electricity and provides a good seal.
Features:
- Applied by brush or spatula/blade
- Produces no smoke
- Excess product is easily removed
Scotch-Calk
Comes in preformed strands. It is very simple to shape and apply, and can be bent, extended, widened, and flattened. It is used to seal openings and impacts.
Features:
- Good adhesion
- Flexible
- Waterproof
- Does not stain paint immediately
Vibration Damping Mastic Sealant
Comes in the form of preformed strands. It is flexible and offers excellent adhesion to metal, and is easily cut.
Features:
- Fast application
- Mimics the factory finish
- Requires surface cleaning before application
- Covers the surface effectively
Firm Joint Compound
A firm but flexible joint compound characterized by self-leveling properties. It can be smoothed with a wet finger and then painted.
Features:
- Easy to apply
- Quick-drying
Another clear sealant product currently available offers good adhesion to painted metal.
Sealant Application Tools
Sealant application guns, whether manual or pneumatic, vary in finish depending on the gun type and nozzle.
Manual Cartridge Gun
A manual gun for cartridge fillers, where the product is inside the cartridge (similar to silicone).
Manual Gun for Cartridges and Bags
The cartridge is inserted into the body of the applicator.
Pneumatic Gun (for Cartridges)
A pneumatic gun for cartridges with a pressure regulator. The sealant is contained within a rigid cartridge. An air hose connects to the bottom, and pulling the trigger allows air pressure to enter, dispensing the product.
Pneumatic Gun for Cartridges and Bags
In this gun, the cartridge is introduced into the body of the applicator.
Specialized Sealant Application Methods
Sealant nozzles typically come in various designs to suit different applications.
No-Clean Pneumatic Gun
Designed to connect to sealants that use a disposable nozzle. Air pressure is introduced into the bag, forcing the product out without coming into contact with the nozzle. This type is often used with two-component polyurethane sealants, ensuring the gun never gets dirty.
Pneumatic Gun for Internal Cavity Application
Designed to reach inaccessible areas. It features flexible tubes or hoses that can access internal areas and cavities, such as inside doors. Can also be used for wax application/removal.
Two types of probes are available:
Hook Probe
50cm in length, one end connects to the gun, the other has a hook for spray orientation.
Flexible Tube Probe
Approximately 150cm long, with one end connecting to the gun. The other end features a 360-degree jet, ensuring complete coverage of the surface, both front and back.