In automotive lighting design, surface finishes matter. they contribute significantly to the vehicle’s aesthetics. achieving the perfect surface finishes for the lighting prototypes is critical for a successful project. In this article, we will explore various techniques commonly used in prototypes of Automotive lighting.

PS: The below picture is from the parts a long time ago that are already on the market now and some picture is from a public platform, KUSLA follow a customer non-disclose policy.

Types of Surface Finishing Techniques


Painting black is commonly used for bezels, housings, and the black part of the bi-color outer lens. High gloss black is needed to simulate a tooling part such as bezels. To get a perfect result, the prototype surface needs to be polished to be smooth, then paint evenly on the surface of the prototype, and the thickness of the paint needs to be controlled as much as possible. This is related to the experience of the worker due to this process usually being done manually in the prototyping process.

Vacuum Metallization

Vacuum metallization is to deposit an ultra-thin layer of Aluminum onto the surface of a plastic substrate. This is done within a vacuum chamber, where Aluminum vapor is carefully condensed onto the plastic. The result matters due to it not only contributes to aesthetics but also the function of lighting photometry. To achieve the right reflectivity of the optic, reflect, this process on the prototype needs to be done the same as the mass production process.  

PVD Vacuum Metallization

This technology is usually used on car logo lenses or bezels to achieve an effect that in static looking, looks like a metallization effect but when it is lit on, the light can pass through the thin Aluminum layer to have styling lit-on looking.


Chroming is a surface finishing technique that involves the application of a layer of chromium onto a substrate, typically an external bezel in automotive lighting prototypes. This process creates a surface that not only shines but reflects like a pristine mirror. Another reason to use this process is scratch and weather resistance needs due to this part being out of a lamp and exposed to the environment.  


Grained surfaces can give lighting components a distinctive appearance that sets them apart from the ordinary and it is also used for improving the homogeneity of the lit-on appearance. According to the sample of common graining types such as the VDI series, we can make it on the prototypes.

Laser graining

Some of the Graining can not be done with the traditional prototype graining process, but only be done by laser to reflect the appearance that a styling designer wants. This could be done on an aluminum prototype with a laser. Just like mass production, this kind of training will be done on the tooling steel.

Laser etching and engraving on the PMMA part

Laser etching could provide that kind of effect that traditional processes can not achieve. In ambient lighting, to get a special lit-on dots aspect, laser etching after a black painting on clear PMMA needs to be used.

For some optic microstructures on a clear part, laser engraving can get a smaller size than traditional CNC machining which could provide a more homogenous lit-on appearance.

Hot stamping

Hot stamping is a technique that involves transferring a foil or pre-dried ink onto a plastic surface using heat and pressure. it offers designers the freedom to customize lighting components with brand logos, emblems, or unique patterns Which could enhance the appearance of lamps.

Brushing Effect

Automotive lighting components like headlamp bezels can benefit from the brushing effect, giving them a unique appearance with a high-end look. The brushing effect is achieved through a mechanical or chemical process that creates fine parallel lines or grooves on the surface of the plastic prototypes.


surface finishing is another key technique in optic prototypes in a lit prototype project. To fulfill the different demands of our customers, KUSLA works with our partners to realize different surface finishing techniques to make the prototypes the same as tooling parts as much as we can.  If you have any questions about these surface finishing techniques on a plastic prototype, welcome to contact us, we can find a proper way to help you realize your design intention.

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