yessss it has a thin layer of plastic fixative spray or something like that, it's the spray you apply over painted ceramic to make it last it works for everything actually (:
mine's called "ROEL Fijador Plástico, para manualidades y trabajos artísticos, pastel, carbón, lápiz, grafito, entre otros" but it's from Mexico, so yeah, I guess you can google it and get an idea of what it is
it works for everything actually (: