Rather than simply applying a single colour, Coenen explored various techniques that could enable the introduction of pattern to the aluminium oxide layer on the metal's surface. "This ...

(aq) \rightarrow \mathbf{4}Al\, (s) + \mathbf{3}O_{2}\, (g)\) The equation shows you that for every two moles of aluminium oxide oxidised, four moles of aluminium metal are obtained along with ...