Select adhesives for different areas of collision repair

Oct. 4, 2022
Shorter cartridges can provide access in tight areas

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What you will learn:

  • Most OEMs prefer crash-durable adhesives for certain components for which breaking away is not needed.
  • There are three types of seam sealers: Heavy-bodied (non-sag), controlled flow, and self-leveling. 
  • A shorter cartridge is ideal for applications like wheel wells, trunk lids, and any confined space where a larger cartridge won’t fit.

A top priority for the automotive industry is that their vehicles are repaired properly. Automotive repair adhesives are used for a range of purposes, including panel, weld and rivet bonding, plastic, finishing or cosmetic repair, seam-sealing, and sound control. Understanding the diverse variety of adhesives and how they are used for different areas of repair is vital to ensuring the repair work is done correctly.

Metal bonding

When working with metal, particularly panel, weld and rivet-bonding of properly prepared quarter panels, rear body panels, roof panels, door skins, van side panels and outer truck bed panels, using the correct metal bonding adhesive for the application is imperative. There are a variety of metal bonding adhesives, each with properties designed for different work times and environmental conditions including ambient temperature and humidity. Additional features and benefits can include reduced cycling times, versatility and environmental resistance.

Crash-durable adhesives

One type of automotive structural adhesive, crash-durable, is the preferred product for parts where flexibility in a high-impact collision is crucial.

“These bonding adhesives will collapse on impact, similar to an accordion,” says Patrick Maloney, global sales and business development manager AAM and specialty chemicals for LORD Corporation. “Yet, they will retain the strong bond between the two substrates.”

Crash-durable adhesives are designed to conform with rather than break away from the substrates as they deform in a crash. They are more flexible than adhesives designed to break away, and they improve the performance of a vehicle’s body structure sections during a crash. These adhesives also contribute to a significant increase in energy absorption, which makes them an ideal solution in certain applications when compared to traditional metal joining techniques The vehicle manufacturers (OEMs) ultimately determine which application is required for the different car components, which is why following their repair procedures is strongly recommended.

Most OEMs prefer crash-durable adhesives for certain components for which breaking away is not needed. For example, the crash-durable adhesive is appropriate for the vehicle’s apron but not for the radiator support. The manufacturer considers safety when identifying which components should collapse and which should break away. Depending on the repair work needed, the OEM manual may indicate that one or both types of adhesives should be used.

Bonding to plastic

Plastic repair allows for a bit more flexibility than metal-bonding in the products that can be used. As with metal-bonding adhesives, each plastic repair product has specific properties that make them a better choice in different situations. When contemplating the options for plastic repair, ambient temperatures and time of year should be considered. Each plastic repair product also has a slightly different application.

For instance, plastic repair is typically either structural (e.g., a broken or cracked front bumper) or cosmetic (e.g., a gouged front bumper), and the appropriate adhesive will differ accordingly. Knowing the correct plastic repair adhesive for the repair, based on a range of factors, will help ensure the proper adhesive is applied, and the repair work is done correctly. Ultimately, as with any repair work, body shops should always follow OEM procedures.

Seam sealers

Knowing what type of finish you are trying to accomplish for the repair is the first step when choosing a seam sealer. There are three types of seam sealers:

  1. Heavy-bodied (non-sag)
  2. Controlled flow 
  3. Self-leveling

Non-sag is a product that stays in its form as it is dispensed. Controlled-flow, on the other hand, changes its shape as it comes out of the mixer but is not level as it is with self-leveling products.

Sound control is also an important feature to consider when selecting a seam sealer. When sound control is required as part of the repair process, the objective of every body shop should be to duplicate the OEM’s sound-deadening material on surfaces like floor pan interiors.


When working with bare metal and metal bonding, achieving full coverage of the surface or “buttering” for corrosive protection is an imperative. In buttering, the material is pre-applied and spread with an acid or similar brush or spreader to pre-coat and completely cover the area leaving no portion of the bare substrate surface exposed.

“Whether that is with a seam sealer, a panel bond or metal adhesive, fully buttering the area will reduce the potential for undetected bubbles that will lead to rust in the area not protected and other issues that could arise,” explains Maloney.

Ensuring full coverage in tighter areas can be challenging. Fortunately, shorter applicators and cartridges are available to ensure ease of access.

Shorter sealer cartridges—less waste with the same performance

A common dilemma for repair technicians is how to get the material into those tighter repair spots. A shorter cartridge is ideal for applications like wheel wells, trunk lids, and any confined space where a larger cartridge won’t fit. Parker LORD’s Fusor repair adhesives are available in 210 ML cartridges, which are user-friendly and ideal for compact spaces.

In addition to allowing access to snug spaces, shorter cartridges can also be cost-effective. While the 210 ML cartridge is considered the perfect solution for compact areas, a shorter (50 ML) cartridge is ideal when the technician does not anticipate using the entire 210 ML cartridge. These shorter cartridges can reduce waste and may also simplify the billing process for body shops.

While the industry offers a standard-sized short cartridge, the smaller (50 ML) size does hold less material, which could require the technician to switch between cartridges while working. Thinking through the repair process before they start will help the technician reduce the need to repeatedly swap cartridges.

When working with repair adhesives, restoring the vehicle to pre-accident condition is the goal.

Before beginning any vehicle repair, we urge technicians to always reference the most up-to-date OEM repair procedures.

If you would like to better understand the differences and repair techniques for structural and crash durable adhesives, Parker LORD offers structural and mechanical bonding repair clinics.

About the Author

Leif Hansson

Leif Hansson is a technical account manager for Parker Hannifin.

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