Structural Color on Pencil Lead Formed by Plasma Etching

The development of a simple and rapid technique to form structural colors would be an important step to achieve the coloring without dyes containing toxic organic dyes or heavy metals. Here, a novel method to form structural color using plasma etching is presented. The structural color is reproducibly formed by the plasma irradiation of the surface of a pencil lead for 40-120 s. The color changes with the plasma irradiation time. The formed colors exhibit a luster and turn blue, yellow, red-purple, blue, green, or pale red by the plasma irradiation time of 40, 60, 80, 90, 100, and 120 s, respectively. The surface asperities due to the removals of the graphite at the surface of the pencil lead by the plasma etching are changed by the irradiation time. This causes the changes in the structural color of the pencil lead. The coloring by this method can easily control the colored part by using a masking plastic plate. Furthermore, a paper painted with a pencil is also colored by the plasma treatment. The presented method is a simple and rapid technique to form structural colors and can be applied for coloring without dyes.

Automated summary

The development of a simple and rapid technique to form structural colors without toxic dyes or heavy metals is important. A novel method using plasma etching to achieve structural color is presented. The color changes with the plasma irradiation time and can be controlled by using a masking plastic plate. This method can also be applied to color paper using pencil as the pigment.