## 3 Results and Discussion
In the center of the circle a strip was colored to light golden (D), and finally, part of the whitish surface of the same sample was colored to dark golden (E). Such manipulation of colors demonstrates the reproducibility and sustainability of these samples. The erasing and alteration of colors were achieved by changing the fluence of the laser beam by varying the position of the sample from the focus position (0.5 J/cm\({}^{2}\) to 1.0 J/cm\({}^{2}\)). The surface was restored to each previous color by irradiating at a smaller fluence with regard to the initial coloring procedure by changing the processed sample position with respect to the focal plane of F-Theta lens and ablating the existing patterns. In that case, the number of pulses on the surface area and the resulting incident fluence were governed by the scanning speed for each color at 150 kHz repetition rate. The slower speed (i.e; below 70 mm/s) resulted in an excessive absorbed energy and a rather roughly treated surface due to its ablation, whereas the  
Figure 5: Demonstration of erasing the color from the treated sample and formation of new colors produced on the erased surface of aluminum. Panel (**a**): original sample; panel (**b**): explanation of panel (**a**): **A**, initially created dark golden disk. **B**, whitish color after erasing dark golden color, **C**, black semi-circle after erasing whitish color, **D**, light golden strip after erasing whitish color, and **E**, dark golden color painted on the whitish color. The scanning speeds for dark golden, white, black, and light golden were 70 mm/s, 1500 mm/s, 10 mm/s, 200 mm/s (two runs) respectively. The fluence of the laser beam was in the range 0.5–1.0 J/cm\({}^{2}\). Figure 5b represents the images of A, B, C, D and E parts repectivly. higher speed (i.e; above 200 mm/s) resulted in an under-structured LIPSS pattern. The former case corresponded to the black color due to random non-uniform structure formation similar to that demonstrated in [56], whereas the latter case resulted in less pronounced periodic structures with faint images of diffracted golden or brown colors. Finally, we found an optimal scanning speed for every color formed, with speeds ranging from 10 mm/s for the black color up to 1500 mm/s for the whitish color. The formation of LIPSS was found to be most efficient at an optimum scanning speed of 500 mm/s, at which the number of pulses and total incident fluence per unit area resulted in the generation of structures with more pronounced periodicity, sharp images of ripples, and multicolor properties as a function of the viewing angle. Alongside the manipulation of the colors of the treated samples, we also characterized the wettability of the surfaces possessing different colors. Characterization of wettability was done by measuring the static contact angle, using a sessile drop optical measurement method. We used drop shape analyzer (100 Expert, KRUS) to measure the contact angle of smooth surfaces where the drop lies on the solid surface. We measured the surface morphology of different colors using SEM. Variable scanning speeds were used to achieve different colors on the aluminum surface. Black, brown, golden, and iridescent colors were obtained at the speeds of 10, 70, 200, and 500 mm/s, respectively. SEM images (Figure 6) show the morphologies of the surfaces processed at the above-mentioned scanning speeds. It is clearly seen from the images that the low speeds of processing (10 and 70 mm/s) resulted in the formation of non-periodic micro- and nanostructures on the surfaces (Figure 6A,B). This is well understood as a higher number of overlapped laser shots hit the surface resulting in greater absorbed energy and stronger ablation of the material. One can see the appearance of nano- to micro-sized particles between the \"mountains\" and \"valleys\" of those images. The golden color was produced at 200 mm/s and at this speed the periodic structures started to appear (Figure 6C).