Editing a material by foaming or recolouring with a laser is also a special type of laser marking in which the laser only processes the surface of the material.
Plastics often consist of different materials that react differently when processed with a laser. Not only the raw material plays a role, but also individual colour pigments or other mixed components contained in the material e.g. additives, fillers or protective substances influence the laser result.
If you want to apply permanently durable markings on plastics, engraving by laser is the most popular alternative. In contrast to traditional methods such as printing or embossing, laser engraving is extremely durable and high-contrast markings can be applied.
Most plastics can be marked very well with the laser but some only with the addition of certain additives. Here, the polymer is melted and it forms a foam-like structure. That is why this process is called foaming. In this way, bright plastics can be marked dark and dark plastics can be marked brightly. With certain additives, laser marking is even possible in colour.
Plastics can be processed by colour change when marking. In this case, the power of the laser beam changes pigments of the work piece to be processed in their optical property and the surface of the work piece remains virtually undamaged. The plastic material is processed only at a depth in the μ range.
When foaming, the surface is caused to melt by the action of heat by means of laser. As a result, gas bubbles form on the material and the volume is increased. The carbon contains and the plastic oxidizes to carbon dioxide which escapes and forms a foam layer (elevation). This achieves the desired contrast and creates a "raised" mark.
This method, for example, is used in marking of computer keyboards and electronic components application. Additions of additives in plastics enhance this effect and even produce certain colour shades. Depending on the composition, the discolouration is lighter.