Detectable warning plate with patina

Stages of Rust

When oxidation occurs, the metal’s surface forms a scale that darkens to a patina. The alloy in question will determine if the corrosion is invasive or not. In cast iron, rust—a ferrous oxide—can form a thin, protective layer against pitting.

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A mold cavity for a complex casting is pressed into the grey color sand in the swing of a vertical mold

11 Metal Casting Methods

Metal casting is the process of pouring molten metal into a shaped space so that it will cool and harden in that form. For many items, this process can be less expensive than machining the part out of a piece of solid metal. Even though the idea behind it seems singular and simple, there are many ways foundries cast objects. How they make a metal casting mold will depend on the metals used, the size of the run, and the shape, symmetry, and complexity of the casting.

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