	Laser Markers

Mechanism of Coloring Plastic Targets

Changing the color of plastic targets by marking is based on major four major principles:

1. Bubbling
2. Condensation (using additives)
3. Carbonization (using additives)
4. Chemical change

1. Bubbling

When a laser beam is applied onto a base material, the heat vaporizes the material and generates gas bubbles. The bubbles are trapped under the surface layer of the base material and create whitish bumps. With dark-colored base materials, the marking appears as a lighter color of the base material, offering high visibility.

Example:

Black material -> Gray marking, Red material -> Pink marking

2. Condensation

When an additive absorbs the energy of the laser, its molecule density increases due to the heat and causes condensation, turning the plastic darker. The additives are generally called coloring agents, but they can be considered to be pigments having high laser-beam absorptivity.

3. Carbonization

If the base material containing the additive continuously receives high energy, the increased laser-beam absorptivity causes carbonization of the surrounding polymer, resulting in a black coloring. Carbonization does not occur in a base material without an additive.
The additives are generally called coloring agents, but they can be considered to be pigments having high laser-beam absorptivity.

4. Chemical change

Every pigment added to the base material contains metal ions.
The application of the laser changes the crystal structure of the metal ions and the amount of hydration in the crystal. This causes a chemical change in the composition of the pigment component, resulting in a concentration of the pigment and a change in color.

Summary

The base material of plastic is basically white or pale yellow.

	Bubble marking is a condition where dark-colored material appears white and embossed, or paler than the color of the base material.
	The condition where a pigment vaporizes and vanishes due to the laser's heat, leaving the color of the base material visible is also considered bubble marking.
	Dark, black marking is caused by carbonization. This indicates that the base material contains an additive, or a pigment that easily absorbs laser energy.
	Chemical change is marking which changes the color of the pigment itself.

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