into the corrugated plate illustrated in fig1 as briefly discussed above the sheet stock may be supplied in discrete lengths or normally for sheet stock of lesser thickness in large coils which are continuously fed through the corrugator downstream of the corrugator the corrugated plate may be severed into pieces of lesser length if desired when the plate is to be coated and particularly when it is to be zinc coated or galvanized for example with a three ounce coating 1 5 oz of zinc per square foot for each side of the plate the coating can be performed at coating bath 22 before the plate is corrugated this is possible because of the large curvature radius r of the convex peaks and convex troughs 6 8 respectively of the corrugated plate this large curvature radius subjects the zinc coating to only minor stretching and compressing while the sheet is deformed in corrugator 10 and the coating can normally withstand it without cracking or peeling although it could not withstand the more severe stretching and compressing to which it would be subjected in the manufacture of conventional corrugated plate having a much smaller curvature radius of one inch or less by galvanizing the plate in its flat state the handling of the plate is simplified and the galvanizing bath can be maintained smaller both of which reduces the manufacturing costs and therefore the overall costs.