A cracked car bumper does not always need to be replaced. Many types of damage to the plastic bumper cover can be repaired with an appropriately selected bonding system, but the success of the repair depends first of all on the plastic type, the location of the damage, surface preparation and the adhesive system.
The most common mistake is buying a product described simply as a “strong plastic adhesive”. Bumper covers can be made from PP/EPDM, ABS, PC, PA, PUR and other plastics, and these materials differ significantly in bondability.
This guide explains how to identify the bumper material, when bonding makes sense, which adhesive technologies can be considered for PP and ABS, how to repair a crack step by step and when the vehicle manufacturer’s repair procedure must take priority.
Key takeaways
- Check the material marking on the inside of the bumper cover before choosing an adhesive.
- Not every “plastic adhesive” is suitable for PP, PE, ABS and PUR.
- Professional automotive-plastic repairs commonly use dedicated two-component polyurethane repair systems such as TEROSON PU 9225.
- TEROSON PU 6700 is a versatile polyurethane adhesive, but Henkel explicitly states that it is not recommended for PP and PE.
- Where the repair system requires an adhesion promoter, use the product specified for the exact adhesive variant and substrate.
- Larger cracks may require reinforcement on the reverse side.
- Before repairing a modern bumper, check whether radar, parking sensors or other ADAS components are located behind the damaged area and follow the vehicle manufacturer’s restrictions.
Can a cracked car bumper be bonded?
Yes. Many types of damage to a plastic bumper cover can be repaired by bonding. Depending on the material and repair system, this can include cracks, scratches, small holes, missing material and selected mounting-point damage.
The decision should not be based only on crack length. Check:
- plastic type,
- location of the damage,
- condition of the surrounding material,
- whether both sides of the crack can be prepared correctly,
- whether sensors or radar units are located behind the repair area,
- the vehicle manufacturer’s restrictions for repair or replacement.
Bonding is only one repair method. Depending on the plastic and the damage, workshops may also use plastic welding, hot stapling, reinforcement or complete component replacement.
Bumper cover and bumper reinforcement are not the same thing
In everyday language, “bumper” usually refers to the visible plastic exterior part. Technically, this is primarily the bumper cover or fascia.
Behind it there may be:
- energy absorbers,
- metal or composite reinforcement beams,
- mounting brackets,
- parking sensors,
- blind-spot or other radar units,
- wiring and other equipment.
The adhesives discussed in this article concern mainly plastic exterior body parts. A damaged reinforcement beam, energy absorber or structural component should not be treated as an ordinary plastic crack.
How do you identify the bumper plastic?
Before choosing an adhesive, inspect the inside of the component. Vehicle manufacturers commonly mould the material code into the plastic.
| Marking | Material | What matters for bonding? |
|---|---|---|
| PP / PP-EPDM | Polypropylene or elastomer-modified polypropylene | Low-surface-energy material; use a repair system confirmed for the substrate and follow the required surface preparation and adhesion-promoter procedure. |
| ABS | Acrylonitrile butadiene styrene | Usually easier to bond than PP, but still requires compatible adhesive chemistry and controlled preparation. |
| PC | Polycarbonate | Confirm chemical compatibility with the adhesive and refinishing system. |
| PA | Polyamide | Properties can vary with grade, fillers and moisture content. |
| PUR | Polyurethane | Use a repair material intended for compatible automotive polyurethane substrates. |
| No readable marking | Unknown | Do not guess. Identify the material before selecting the repair technology. |
Which adhesive should be used for PP, ABS and other bumper plastics?
PP and PP/EPDM bumper covers
Polypropylene has low surface energy, so many conventional adhesives do not bond to it reliably without a dedicated system.
For PP or PP/EPDM, use an automotive plastic-repair system whose documentation confirms compatibility with the substrate. Where the system specifies an adhesion promoter, apply the correct product for the exact adhesive variant.
ABS bumper covers
ABS is included among the plastics commonly repaired with products from the TEROSON PU 9225 family. Cleaning, mechanical preparation and correct mixing of the two-component adhesive still remain essential.
What about PE?
Do not use an adhesive merely because the label says “for plastic”. Check the exact TDS. For example, Henkel explicitly states that TEROSON PU 6700 is not recommended for PP and PE.
Bonding or plastic welding – which repair method is better?
Neither method is universally better. Both are used in professional plastic repair.
Bonding
A dedicated repair adhesive can rebuild cracks, holes and missing material without melting the base plastic. After curing, suitable repair compounds can be sanded and prepared for refinishing.
Plastic welding
Plastic welding softens or melts the base material and joins it using compatible filler material. Correct plastic identification and temperature control are essential.
Workshops may also combine methods, for example stabilising the crack first and then rebuilding the damaged area with a dedicated repair compound.
Which TEROSON adhesive should be used for bumper repair?
The older English version focused mainly on TEROSON PU 9225 and PU 6700. The current Polish article distinguishes the products more precisely.
| Product | Characteristics | When to consider it |
|---|---|---|
| TEROSON PU 9225 | 2K polyurethane repair adhesive for painted plastic vehicle parts; longer working time within the 9225 family. | Repairs that require more time for positioning and modelling the repair material. |
| TEROSON PU 9225 SF | Fast 2K version; approximately 2 minutes working time and rapid further processing under the specified conditions. | Faster repairs of plastic body parts. |
| TEROSON PU 9225 UF ME | Ultra-fast 2K repair adhesive with approximately 1 minute maximum processing time. | Smart repair and small repairs where rapid further processing is required. |
| TEROSON PU 6700 | Versatile 2K polyurethane adhesive for many substrates; Henkel does not recommend it for PP or PE. | Compatible plastics and multi-material body repairs where the substrate is confirmed by the TDS. |
| TEROSON 150 | Adhesion promoter for plastic-repair systems. | Where the selected TEROSON repair system specifies surface activation or adhesion promotion. |
TEROSON PU 9225
TEROSON PU 9225 is a two-component polyurethane adhesive intended for repairing plastic parts inside and outside the vehicle, including bumpers, spoilers and trims. The cured material can be sanded and prepared for painting as part of the repair system.
TEROSON PU 9225 SF and UF ME
TEROSON PU 9225 SF is intended for faster work, while TEROSON PU 9225 UF ME is the ultra-fast option.
With very short working times, the surface, cartridge, applicator, static mixer and reinforcement materials should be prepared before dispensing begins.
TEROSON 150 – when is an adhesion promoter required?
TEROSON 150 is an adhesion promoter for plastic-repair systems. Use it when specified for the actual repair adhesive and plastic.
Do not choose the primer from memory. The recommended pretreatment can differ between product variants.
TEROSON PU 6700 – not for every bumper
TEROSON PU 6700 bonds a wide range of materials, including metals, wood, painted surfaces and compatible plastics. Henkel explicitly states that it is not recommended for PP and PE.
TEROSON products for automotive plastic repair
How to repair a cracked bumper step by step
1. Assess the damage and check the vehicle manufacturer’s procedure
Inspect the crack, mounting points and components behind the bumper cover. Identify any parking sensors, radar units or other ADAS components before deciding that the area can be repaired.
2. Remove the component if necessary
Access to the back of the bumper is often necessary for a controlled repair and for checking the material marking and hidden damage.
3. Identify the plastic
Locate the moulded material code on the inside of the part. Use this information to select the adhesive and pretreatment system.
4. Wash the surface before sanding
Remove road dirt, salt, waxes, silicones, dressings and other contamination before mechanical preparation.
5. Prepare the repair area mechanically
Prepare the crack edges according to the repair-system instructions. The process may include removal of damaged material, controlled abrasion and creation of a repair geometry that gives the compound sufficient bonding area.
Do not remove more sound material than necessary.
6. Clean and degrease after mechanical preparation
Remove sanding dust and use the cleaner specified by the repair-system manufacturer. Henkel commonly specifies TEROSON VR 10 in its repair procedures.
7. Apply an adhesion promoter if required
Use the correct promoter for the exact plastic and adhesive system. Do not treat this as an optional generic step or automatically apply one primer to every repair.
8. Reinforce the crack where required
Larger damage may require a reinforcement material on the inside of the component. The goal is to spread the load over a wider area rather than concentrating it directly along the crack line.
9. Mix and dispense the 2K adhesive correctly
Use the correct applicator and static mixer. Purge the cartridge as required by the product instructions before applying material to the repair area.
10. Respect working time and cure before sanding
Fast products give very little time for correction. Complete positioning before the working time is exceeded, and do not sand or load the repair before the specified stage of cure.
11. Finish and refinish the repair
After the repair compound has reached the required condition, perform the mechanical finishing and refinishing steps specified by the repair and paint systems.
Bumper repair and ADAS radar – why the OEM procedure matters
Modern bumper covers may sit directly in front of radar sensors used for blind-spot monitoring, adaptive cruise control and other driver-assistance functions.
Repair material, local thickness changes, filler and refinishing can change how radar waves pass through the bumper cover. Because requirements vary by manufacturer, model and sensor location, there is no universal “safe repair distance”.
I-CAR’s collection of OEM position statements shows that some manufacturers prohibit plastic substrate repair in defined radar zones, while others impose paint-thickness or refinishing restrictions.
What happens after repair and painting?
After the bumper repair is completed, respect the curing requirements of both the repair material and the paint system.
There is no need to use a special cleaner merely because the bumper was bonded. Once the complete repair and refinishing system has fully cured, maintain the surface according to the coating manufacturer’s requirements.
A car-body cleaner does not “preserve” the adhesive joint. Long-term repair durability depends mainly on correct material identification, surface preparation, adhesive application, cure and finishing.
Common mistakes when bonding a cracked bumper
- Buying a “plastic adhesive” without identifying the bumper material.
- Assuming every polyurethane adhesive bonds well to PP.
- Using TEROSON PU 6700 on PP or PE despite the manufacturer’s limitation.
- Skipping the adhesion promoter where the selected system requires it.
- Bonding dirty, oily or silicone-contaminated plastic.
- Skipping mechanical preparation of the repair zone.
- Applying a large quantity of adhesive without preparing the correct repair geometry.
- Incorrectly mixing a two-component adhesive.
- Exceeding the working time before the repair is positioned.
- Sanding before the repair compound has developed sufficient strength.
- Repairing a radar transmission area without checking OEM restrictions.
- Inspecting only the visible plastic and ignoring reinforcement beams, absorbers and mounting structures behind it.
FAQ – bonding a cracked car bumper
What is the best adhesive for a cracked car bumper?
Start by identifying the plastic. For many professional automotive plastic repairs, dedicated two-component polyurethane repair systems such as the TEROSON PU 9225 family can be considered, but substrate compatibility must be confirmed.
Which adhesive should be used for a PP bumper?
PP is a low-surface-energy plastic. Choose a repair system whose manufacturer confirms compatibility with PP or PP/EPDM and follow its required surface preparation and adhesion-promoter procedure.
Is TEROSON PU 9225 suitable for bumpers?
Yes. The TEROSON PU 9225 family is intended for repair of automotive plastic parts including bumpers, spoilers and trims.
Is TEROSON PU 6700 suitable for a PP bumper?
No, this is not the recommended direction. Henkel explicitly states that TEROSON PU 6700 is not recommended for PP and PE.
Can a cracked bumper always be repaired?
No. The material, damage location, reinforcement behind the cover and the vehicle manufacturer’s repair procedure all matter. Radar transmission zones can have strict no-repair requirements.
Should the bumper be welded instead of bonded?
Both technologies are valid for appropriate materials and damage types. Choose the method according to the plastic, the repair-system instructions and the vehicle manufacturer’s procedure.
Related automotive bonding guide
For another vehicle-repair application, see Gluing and repairing car windows – how to replace a windscreen correctly.
Not sure which system is suitable for your bumper?
Check the material marking on the inside of the bumper cover and prepare a photo of the damage. If the vehicle has radar or sensors behind the bumper, include the make, model and year so the OEM repair restrictions can be checked first.
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