Modern Implications

The surface of the aluminium profile is lightly drawn with a smooth hard object, which can leave a white mark on the surface of the profile. If it can be wiped off by hand, it means that the anodised film is not wiped off. If it cannot be rubbed by hand, the anodised film has been wiped off, indicating that the anodised film is poor in firmness and too thin, and the surface quality is poor. The average film thickness of the anodised aluminium profile for doors and windows needs to be at least 15um.

Types of Iron fence casting

Most of these features, which used to be unique to iron, are now available in steel, which is by a large margin the superior material. And visually, the only difference between the two is the texture. Steel is smooth, while iron has a visible grain, whether it is produced by casting, or by pulling. This grain is actually caused by impurities in the iron and is what accounts for its unreliable nature. These impurities cause weak points in the iron that can lead to breakage when it’s put under stress. Steel’s smooth appearance results from the fact that these impurities have been burned out, or, in the case of carbon, evenly distributed throughout the material. When you think of the medieval blacksmith hammering away, what he is doing is distributing the carbon evenly to turn iron into steel.