(excerpts from JIS G3314)
| • | Aluminum is apt to form alloy with iron and as the coating bath temperature is considerably high, Al-Fe alloy layer is apt to develop during production. This alloy layer has an adverse effect on formability and thus for such applications as heat-resisting equipment that requires forming process, it is necessary to suppress the development of the alloy layer to the minimum during production, for which silicon add to aluminum effective. |
| • | A common practice is to add approximately 5-11% of silicon to molten aluminum during production. |
| • | ASTM Type 2 (hereinafter called Type 2) made in the U. S. includes products manufactured through a process that does not add silicon but these products are seldom formed into roofing of the building and primarily used in applications not subjected to high temperature. |
| • | Photo 1 shows, as an example, cross sections of layers from different coating bath compositions. As can be noted, "Pure aluminum type" has a much larger growth of layer than "Al-Si alloy type". |
