Metal workers at an aluminum course, which was organized by the Gewerbefoerderungsstelle der Handwerkskammer Berlin ( Office for the Advancement of Crafts of the Berlin Chamber of Crafts) in cooperation with the Aluminium Centre for the retraining of the German handicraft workers in new raw materials. Here, during the hot forging, is determined the temperature with a pine wood shaving, which, after being put in the heated place, leaves a black coal line on the workpiece as it reaches the proper working heat.
