In one example, a print job is received. The X and Y values are distances, which when smoothly connected by an appropriate continuing curve, define airfoil profile sections at each distance Z. The method is characterized in that after the above arsenic, antimony andor selenium is selectively adsorbed and eliminated, further the above chromium andor copper is selectively adsorbed and eliminated. A control terminal of the first switching transistor is connected to a control wire.