Files are made of

Finish Concentric Hole

Wrought Iron

Wrought Iron is the purest form of iron; although it may contain traces of carbon. It is usually made by ‘‘puddling process’’. It is very costly and its use has been almost totally replaced by cheaper steel. However, for some components like chain-links and Crane-hooks wrought iron is still the preferred raw material.

Black

In Oxy acetylene welding, color of oxygen cylinder is Black.

Oxidizing flame