Color change can be an excellent solution without changing material properties, providing adequate contrast, good durability and long-term stability. UV laser marking of aerospace wire and cable meets all these requirements.
Mark cross-sections confirm that the darkened area extends 10-20um below the surface, ensuring that the mark cannot be altered or removed without physically damaging the top layer of the insulating layer.
The question is how light-colored polymer surfaces can darken under laser light without burning or melting. The answer is a magic substance called titanium dioxide (TiO2). Fortunately, this is a commonly used pigment that wire manufacturers use to make insulation appear white or other light colors like gray, blue, green, yellow, pink, etc.