All repair and maintenance tasks shown should be done by professionals only. Please do not try this at home or if not qualified by professional education. Always follow car manufacturer's instructions. Limitation of liability.

Repair a cracked bumper

Use it for any plastic damage, e.g. holes, scratches and cracks

With the increasing use of plastics in automotive engineering, plastic repairs gains more and more importance. Instead of replacing e.g. the full bumper plastic repair allows to reduce material costs and helps recycling. For a more sustainable repair.

Get the Materials

In our instruction we will be showing a bumper repair using TEROSON PU 9225. This is a product recommended for holes, scratches and cracks larger than 7 cm. For fast applications smaller than 7 cm you may also use TEROSON PU 9225 SF or TEROSON PU 9225 SF ME.


Cleaning and Surface Preparation

Remove all major dirt and rinse plastic part with plenty of clear water. Clean and pre-treat repair area using TEROSON VR 20 with lint-free cloth.


Pre-Treatment of the damaged area

For cracks drill out hole at the ends. Hole diameter should be about 6 mm to stop further cracking. Enlarge the crack to the minimum 2-3 mm gap. In case of a hole go to step 3 directly.



Grind a V-groove into the front-face edges of the repair area. The holes at either end should also be V-tapered with a grinder.



Roughen surfaces on both faces with P120-150 grinding paper. Remove the grinding dirt. Don't forget to also sand the back of the damaged area. Clean and pre-treat both faces with TEROSON VR 20.


Primer Application

Spray a thin coat of TEROSON 150 primer onto both faces. Flash off time is 10 minutes at room temperature. Cut a piece of fibre mesh larger than the damage.


Preparation of the cartridge

Open the cartridge and squeeze out a small amount of material until both adhesive components run equally. Apply the mixing nozzle and discard the first 5 cm of the mixed adhesive.


Application Back I

Apply TEROSON PU 9225 to the back of the repair area. Position the fibre mesh over the damaged area and press it down into the adhesive with a spreader until the mesh is saturated.


Application Back II

Apply adhesive on top of the mesh and spread it to cover the repair area completely.


Curing Back

Cure adhesive at room temperature. To speed up cure use an infrared heater at 60°C to 70°C for 15 minutes. Allow to cool down to room temperature before continuing on the front.


Application Front

Apply TEROSON PU 9225 to  the front face, keeping the nozzle inside the material to avoid air pockets. Smooth down with spreader, always from the centre of the damage outwards. Repeat cure as in STEP 9.



Sand to remove excess adhesive on the front face and restore original shape of the plastic part. Start with P150 grit paper and progressively use finer sand paper.


Surface Preparation

Clean and pre-treat repair area using TEROSON VR 20. For optimal adhesion of plastic filler, apply a thin coat of TEROSON 150 primer. Allow 10 minutes flash-off time.


Application of Plastic Filler

Apply TEROSON UP 250 Plastic Filler. Sand down the cured plastic filler and then proceed as instructed in the refinish instructions of the paint manufacturer.

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