How to avoid misuse of collision repair products

March 2, 2018
Before starting a new collision repair job, it’s critical for technicians to understand where to obtain proper repair information and product instructions and how the use – or misuse – of these products can affect the repair’s final outcome and integrity of the vehicle.

Before starting a new collision repair job, it’s critical for technicians to understand where to obtain proper repair information and product instructions and how the use – or misuse – of these products can affect the repair’s final outcome and integrity of the vehicle.

"In general, the most common reason for a product failure ties back to the misuse of a product," says Douglas Craig, structural adhesives applications engineering manager & collision repair industry liaison for LORD Corporation. “Simply not reading instructions causes some failures.”

Crash Durable Adhesives should always be replaced with the same. If in doubt as to whether a crash durable adhesive was previously used, contact the OEM to determine the proper product and process. If not identified in original equipment manufacturer service information, it can often found as a “colorful” material within the joint: blue, orange, red, purple and black.

However, the other 90 percent boils down to two factors: Not leveling two-component cartridges before use and not purging enough material in the mixing nozzle before application.

“When a cartridge is filled the A and B sides are not exactly level,” Craig says. “There could also be an air gap at the top of the package.”

Leveling the cartridge

The ratio of Part A to Part B in a two-component cartridge is critical. An unleveled two-component cartridge can throw off the proper ratio. “If you begin using a cartridge without getting everything equalized, you will be off-ratio,” Craig says.

Once it has been equalized, paying careful attention that the proper ratio can be achieved, the mixing nozzle is attached. The nozzle to be used is chosen using a variety of factors, such as length, the material being used, including its chemistry, ideal working temperature, the amount of adhesive being applied per cycle and the number of times the material is being folded back together. Extrude a mixer length of mixed material and dispose of it.

How to use collision repair adhesives safely

When working with collision repair adhesives, it is just as important to use proper safety habits as it is to use the correct repair product. Be sure to follow these steps before starting a job with collision repair adhesives:

Practice safe habits: Wear proper safety equipment and keep sparks/flames away from the area.

Skin contact: Wear gloves to avoid product contact with skin to avoid irritation or a skin reaction.

Eye contact: Flush eyes immediately with water if a product gets into your eyes. Contact a physician for follow-up.

Flammability: Most adhesives don’t contain solvents and aren’t flammable, read product literature and Safety Data Sheets (SDS).

Common sense: Be mindful of your environment and use common sense. Treat all adhesives with respect.

"However, if we didn't level the cartridge to begin, we will get more of either Part A or Part B," Craig says. "It will coat the inside of the mixer and throw off everything. If you already have more on one side than the other because a material is sticking to the inside wall of the mixer, you may never get on ratio.”

To ensure the cartridge is producing the proper ratio, examine the material as it is coming out of the mixer. It should be a “nice, homogenous mix” without streaks or dark or light spots, he notes.

“If you find you are off ratio, throw away the mixing nozzle and start again,” he says. “That causes the majority of product failures or issues with a product not working properly.”

When working with two-component adhesives, make sure to level the plungers until both sides dispense evenly. Be sure to dispense a mix tip’s length of adhesive and look for good mixing without any streaks

Quick doesn’t equal efficiency

As the old adage goes, time is money. So often the mindset that the more quickly a job can be completed, the more jobs can be completed and the more money can be made. However, this doesn’t mean a collision repairer is being efficient and profitable – or doing repairs correctly. Rushing through a job may very well result in the need for a do-over.

Technicians may oftentimes be in a hurry and focused just on getting a repair job done. However, this can come at a cost. If a less-experienced repairer is observing or working with a skilled technician who is rushing through a job, proper preparation or pre-repair procedures may not be followed. That means the newer technician may be learning bad habits or incorrect use of repair products, without fully understanding that when a two-component system is used where things need to be mixed together, instructions must be followed to make sure the mix is correct.

Craig likens following instructions in the use of collision repair products to baking biscuits. “If you’re making biscuits, you want to leave the butter chunky in the dough – that’s what makes them good,” Craig says. “You need to follow instructions to know how to make them turn out well.”

A cheat sheet to working with two-component adhesive materials


  • Check the manufactured date and shelf life to confirm a product is not expired.
    • If the manufacture date is not clear or not able to be determined, call the technical support hotline and determine how old the material really is.
  • Level the plungers until both sides dispense evenly.
  • Attach the mixing tip.
  • Dispense a mix tip’s length of adhesive and look for good mixing without any streaks.


  • Leave mixing tips on all partially used cartridges to seal except for foams.
  • Due to the expansion rate of the foams, the tip needs to be removed immediately after use to avoid the product from curing back into the cartridge.
  • Keep the adhesive between 60 degrees F to 80 degrees F.
  • Pay attention to the humidity. Urethane adhesives react with moisture so don’t open foil bags unless there are plans to use them.

Work time and temperatures

  • Take note of the “work time” on the adhesive label/literature before starting the collision repair job.
  • Two-component adhesives are accelerated by heat:
    • Work time is based on 70 degrees Fahrenheit.
    • Every 20 degrees Fahrenheit increase in temperature, the work time is reduced by about half, with the same effect for cure time.
    • Every 20 degrees Fahrenheit decrease will extend the work time by half

This is especially important when working with adhesives because they vary in chemistry and best use for an application. Prepping adhesives – epoxies, acrylics, and urethanes – for use has the highest failure rate for this reason.

“All three of these chemistries are adhesives – anything that sticks together is an adhesive," Craig says. "The difference in all of these is the strengths they provide and other properties such as flexibility and corrosion protection. Even seam sealers have some level of strength so they can be considered adhesives. It is the level of strength that really begins to define how you would use it."

It’s all about the chemistry

Within the collision repair industry, acrylic and epoxy adhesives are the two main chemistries accepted for bonding metal panels. (1K windshield urethanes are also used by some original equipment manufacturers (OEMS) to bond roof but require that the e-coat and primer are intact.)

Within panel bonding, this is broken down further into two adhesive categories – panel bonders and crash-durable adhesives (CDAs).

Technicians need to follow original equipment manufacturer (OEM) guidelines when working with collision repair adhesives because chemistry and best use for application varies.

“The dividing line has everything to do with the flexibility and strength of the adhesives – especially over time – and what they can tolerate in a split second of a crash mode,” Craig explains. “All the adhesives are really strong, but the crash-durable adhesives are flexible as they go through an event so they are more in control of the joint.”

The adhesives must be able to maintain 80 percent of its original strength after environmental exposure, with one OEM noting that the most critical test is how they are able to withstand the seven-day water soak.

The joints can be bonded only (just glue), weld bonded using resistance spot welding, or they can be rivet bonded with adhesive. When an engineering team creates a vehicle, it decides if the vehicle will be held together with glue or methods such as welds or fasteners.

A guide to acrylic, epoxy and urethane adhesive chemistries


  • Advantages: Bond bare metals, anti-corrosion properties, fast room temperature cure, color changes when cured.
  • Disadvantages: Odor and tacky surface


  • Advantages: Easy to use, bonds bare/primed metals and plastics, low odor, and can accelerate with heat.
  • Disadvantages: Some are rigid and longer cure times


  • Advantages: Flexible and bonds plastics
  • Disadvantages: Needs primer on metals and moisture sensitive

“Adhesives can live in a world where they are 100 percent in charge of holding something together,” Craig says. “Not using impact-toughened adhesives where a manufacturer may have used them in a vehicle’s construction may change many characteristics of the car at some point in its life. It could affect durability, safety, and the ability to absorb energy in a crash.” Conversely, adding a CDA where no adhesive was previously used could conceivably cause a change. Always refer to the OEM repair guidelines before making repair decisions.”

Understanding the correct adhesives to use in the replacement of metal body panels and plastic parts – which to use and when – is critical. Acrylics and epoxies are primarily – but not always – used for metal only. “There are some epoxies used to hold plastic to metal-framed cars,” Craig says. “Acrylic adhesives will accomplish the same thing but tend to be a little rarer.”

At the end of the day this is another example of how critical the adhesive selection is and how important the OEM repair information will be in guiding the proper choice. “For every generalization there are multiple examples, which are quite different,” Craig says.

When dealing with plastic parts repair, urethane should be used to bond the parts together. “Urethane has more flexibility,” Craig points out. “This doesn’t mean other adhesives aren’t strong, but urethane sticks better to plastics including fiberglass, Kevlar, and carbon fiber.

Knowing how these chemistries work with different parts and that one chemistry cannot do everything is important. It’s also just as essential to understand and adhere to OEM guidelines. “We typically say metal goes with epoxy and acrylic and urethane go with plastic,” Craig says. “But there is a huge gray area where there is crossover, which contradicts this statement.”

Adhesive design, chemistry, and suitability drive application decisions, while referencing technical data sheets and other repair documentation helps to guide the proper choice for procedure and product.

“All adhesives are not designed equally and cannot be placed into one category or another, simply based on chemistry,” Craig says. “Although chemistry is important, repairers need to follow OEM standard operating procedures (SOPs) and use them, accordingly, because there is such a huge gray area.”

Getting access to information

Roughly five years ago, the collision repair industry as a whole decided that the repair standard for any particular car would be the information provided by the vehicle manufacturer.

"This puts manufacturers on the hook for providing all the information when not all of them may have been on board with doing it,” Craig says. “It also makes the assumption that a repair technician is able to understand and even find the information. Any shop technician who is going to make a repair really needs to understand what it means to truly fix the vehicle. At the root of it is the OEM guidelines and repair standards.”

The ratio of Part A to Part B in a two-component cartridge is critical. An unleveled two-component cartridge can throw off the proper ratio.

Each OEM has its service information in a different format, which creates a challenge. There is not always an explanation as to why a particular material should be used or not used on a specific substrate or why a bumper cover shouldn’t be fixed in a certain area, explains Dennis Beardsley, North American training manager for Saint-Gobain and an I-CAR instructor.

“Because of misinformation and lack of knowledge in collision repair, the wrong product is often used because it is handy or deemed good enough,” he says. “The term ‘or equivalent’ is listed in service publications from some manufacturers, but not everyone may know what is an ‘equivalent.’”

A crash durable adhesive should always be used to replace a CDA. “If in doubt as to whether a material is a CDA, be sure to replace it with one unless the OEM advises against this,” Beardsley says.

There are many generic products on the market for collision repair, and the main goal of these product manufacturers is to sell quality products and work with OEMs to develop products that meet their original standards.

“We want to make sure that when we go into service, we are giving the car owner back what he or she had,” Beardsley says. “With the term ‘adhesive,’ there may be 40 or more OEM standards that apply to that adhesive so the challenge then becomes applying it in the non-OEM environment.”

This is when the collision repair product manufacturers need to work with the OEMs to create a new standard that takes the attributes of other standards and compiles them into one document so all the information is at hand to test and create a product that meets the standards.

“When it’s attained at that level, the OEM will recommend these products for vehicle repair,” Beardsley says. “These are the products you want to use to fix a car. Otherwise, it may not do the job it needs to if you are not using recommended OEM products. You should always follow OEM repair recommendations."

He points out that although some product uses and recommendations may seem “basic” – such as leveling plungers – these instructions aren’t always followed.

Creating a repair culture

That’s why it is critical to create a culture with the mentality of looking at what the OEM wants first and then making a repair decision based on that, Beardsley notes. “I’m always going to revert back to OEM info,” he says. “The OEM is the expert. Period. End of story. You need to look at their approved products, determine what the OEM wants – i.e., all adhesives or adhesive and spot welding, or rivets – and make your repair decision from there.”

This is critical for both veteran repairers and those that are new to the industry. The seasoned technicians may know how to properly level a plunger during adhesive repair prep – and understand the significance of doing so – but those learning from them may not.

“It’s really important to reinforce this to the folks you are coaching or teaching,” Beardsley says. “That’s why it’s so important to make sure they have proper training and always have them refer back to the OEM information. No one goes to work thinking, ‘How can I do a mediocre job?’ They are going to do the best they can, but if we haven’t shown them the right way to do something and why it’s important, it’s going to affect the repair.”

Ultimately, it all comes down to doing the job right and “marrying” it to the lifetime of the vehicle. “At the end of the day, the procedure or product specified isn’t our call,” Beardsley says. “We don’t work for any of these manufacturers. The repair and product used is either right or it’s wrong. We, as repairers, cannot alter what the OEMs want.”

Beardsley puts making the proper repair decision and product use in this perspective: “Would I put my two kids in the back of that car after it has been repaired? It really is black and white. The repair procedure and product used is either right or it’s wrong, and these OEM recommendations must be respected.”

For more information on collision repair adhesives and for OEM bulletins on repair recommendations, visit For information on training, visit

About the Author

Tina Grady Barbaccia

Tina Grady Barbaccia is a writer for Advancing Organizational Excellence (AOE). She has written and served as an editor for trade publications, blogs and developed social media and public relations for the construction, engineering, healthcare, agricultural/landscaping and appliance industries since 1998 and is a former editor for ABRN.

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