Crucible steel is a generic term to describe all types of steel formed or melted in a crucible.
Due to the high melting point of pure iron it was not possible to produce steel in the way that was possible with non-ferrous alloys by melting the metals together in a crucible or adding on metal to the melt of the other(s). In addition, even the melting point of steel is higher than the usual furnace operating temperatures, it is only with the ultra-high carbon steels that the melting temperature drops into the normal operating range for ancient furnaces. To add to the difficulties metallic iron is very reactive would attack most refractories extremely fast, hence this technology required the introduction of high quality temperature refractories.
There were three basic ways of making crucible steel.
1. Simply melting a steel of suitable composition.
2. Melting a mixture of low carbon iron and cast iron in a crucible together with a flux to seal the melt to prevent decarburisation.
3. To seal a mixture of phosphorus free low carbon iron and a supply of material with a high carbon content in a crucible, and some fluxing material to form a seal once the mixture had started to melt. Then to heat the crucible so that the iron was carburised to the point that the melting point was reduced to the operating temperature of the furnace.

In the west the first method was developed by Huntsmann (1740s) who melted blister steel in crucibles. Earlier, the second method was used in Italy in the 16thcentury as described by Biringuccio. This has been described as the Brescian or co-fusion process. In Sri Lanka, India, Persia and central Asia there was a long history of producing crucible steel by a variety of processes (variations on 2 and 3 above). Evidence of extensive crucible steel production has been found at Merv (Feuerbach 2002) These steels have been known as Wootz or bulat. Some of these steels are capable of thermo-mechanical processing to produce patterned steel without welding. Such products are often misleading described as being of Damascus steel, however, there is no evidence of self-patterning crucible steels having been produced at Damascus (See Allan and Gilmour 76-79, for discussion of Damascus problem). Such patterned forged crucible steels were not produced by the process of damascening (pattern welding) as was once thought.
Related terms: Wootz, Huntsmann, Watered-silk steel