Sealing Third Brake Lights / CHSML

Efficient and Tailor-Made Third Brake Light Sealing Solutions for Highly Reliable Corrosion and Moisture Protection

To ensure that your innovative automotive lighting systems can function reliably, we offer efficient and flexible sealing solutions to meet your individual requirements. Our two-component sealing foam is installed and compressed in the overall part construction of the vehicle light. This keeps moisture away from the light sources and thus avoids the risk of lighting electronics corroding. The polyurethane-based two-component sealing foams can be applied to a wide range of applications on cars, vans and trucks: front headlights, taillights, third brake lights, turn signals, rear fog lights, license plate lights and multifunctional lights.

Third brake lights installed in rear spoilers or on rear windows with 2-dimensional and 3-dimensional geometry can be sealed using the Sonderhoff FERMAPOR K31 thixotropic polyurethane foams because these adapt excellently to the 3D contour. Using the FIPFG (Formed-In-Place Gasketing) process, our dosing equipment applies a small, fine foam bead to the contact surface or in the groove, ensuring reliability under process conditions and stability guaranteed by the high foam viscosity.

Henkel's Sonderhoff FERMAPOR K31 third brake light sealing foams are ideally suited for the majority of third brake light designs. Although we can produce the sealing material in a range of colors, the seals, in this case, are typically red and not visible under the red cover of the brake light.


Tailor-Made Sealing Solutions for Third Brake Lights

Developed Individually for Your Specific Requirements

The polyurethane foams used for sealing third brake lights are highly water-repellent and temperature-resistant from -40 to +80 °C. They achieve particularly good adhesion to the contact surfaces of common plastic materials. For plastics such as PP or PE, adhesion is often achieved through additional pretreatment with plasma or primer. Due to excellent long-term behavior and the very high resilience of the foam gasket, repeated removal, and installation of third brake lights for repair purposes is possible without the sealing effect decreasing.

To compensate for component tolerances, the polyurethane foam can be easily compressed during assembly thanks to a mixed-cell foam structure with low installation forces. We can modify our formulations to meet many of your requirements.

The different reaction phases of the sealing foam in the chronological sequence

Reference Material

  FERMAPOR K31-A9212-1-rot


Mixing ratio 3.7 : 1 2.3 : 1
Pot life 35 sec. 30 sec.
Tack-free time 5 min. 16 min.
Viscosity A component 46,000 mPas 70,000 mPas
Foam density 0.25 g/cm3 0.31 g/cm3
Hardness (Shore 00) 36 55
Temperature resistance from -40 to +80 °C from -40 to +80 °C
Pretreatment Primer P23 (solvent-based)
P13(water-based) or plasma
Primer P23 (solvent-based)
P13(water-based) or plasma

In addition to the reference products, we develop material systems according to your individual requirements. Influencing factors include pot life until start of foaming, curing time, and the viscosity, hardness, and adhesion properties.

Repeatedly Opening and Reclosing for Maintenance Purposes with Remaining Sealing Effect

The high resilience of the foam seal allows the components to be opened and reclosed repeatedly for maintenance purposes without the tightness deteriorating. After installation, the third brake light is sealed, and the sensitive electronics are protected against splashing water and the effects of the weather.

Watch a video showing the foam compression process.

Cross-section of a polyurethane foam bead in the groove without compression.


Compressing the foam gasket between approximately 30 - 60 % of the original height achieves the required degree of tightness in the installed condition.


DM 502 Mixing and Dosing System with 6-Axis Robot and Mixing Head for Foam Application and Shuttle Table for Picking up Parts for the Third Brake Lights

The reference configuration shown here for sealing the housings of third brake lights consists of our DM 502 mixing and dosing system with 6-axis robot and MK 825 mixing head for foam application as well as a WT 1-LEVEL shuttle table for picking up parts.

The two pick-up plates working in pendulum mode enable the workpieces fixed there to be picked up and processed in one plane. This makes it possible to guarantee continuous operation.

The placement and holding on the shuttle table of the third brake light housing to be sealed is performed either by a machine operator, who can also check the parts for quality, or by a Pick & Place Robot. In this case, an optionally installed camera system could carry out the quality control of the parts.

Flexible and Fully Automatic – According to Your Requirements

For sealing third brake lights, FERMAPOR K31 thixotropic polyurethane sealing foam is applied via the MK 825 mixing head mounted on the robot arm, in a high-precision and fully automatic process, onto the 2D or 3D application surface or into the groove of the component contour. After the dosing cycle, the coupling point of the foam gasket closes almost seamlessly and is thus virtually invisible. Due to the uniform compression in the installed state, a high level of tightness is achieved over the entire contour of the third brake light.

For improved adhesion of the foam gasket to plastics such as PP or PE using plasma, we install an optional plasma application unit on the robot arm in addition to the mixing head.

Even with short cycle times and high unit numbers, the material application process using the FIPFG method is carried out with high dosing precision and repeat accuracy. As a result, you achieve foam gaskets of uniformly high quality. This means that your sealed third brake lights can be processed rapidly, right through to final assembly. This saves time and money.

In addition, our fail-safe mixing and dosing system can be operated easily and intuitively without the need for extensive training. Due to the automatic logging of dosing program data, all process data can be traced and evaluated by the machine operator while production is running.