Which conditions caused the food coloring to form a compound on the surface of the egg?

The food coloring formed a compound on the surface of the egg due to the high concentration of dye coloring in the dye solution and the porous nature of the eggshell. When the dye solution was in contact with the egg, the coloring molecules were able to penetrate the eggshell and bind to the proteins in the egg white, resulting in the coloring compound formation on the surface of the egg.