The temperature of steel when poured into moulds is highly important, and varies with the size of the casting. An experienced foundry superintendent judges the right pouring temperature by simple inspection. Hotter metal is needed for small intricate castings than for large and massive castings.

If metal is too hot, it is very searching, and causes piping or cavities, and possibly shrinkage cracks, by excessive and unequal contraction in the mould. If below a certain fluidity, the mould may not fill completely or cold shuts may be formed. Small bits of aluminum thrown into the ladle reduce iron oxide, thus helping the fluidity of the steel.

After pouring steel moulds, they are watched to see that the mould feeds from the risers and feedings heads, and when the metal has "set," clamps are removed from the flasks, and the mould is somewhat loosened to allow the casting free contraction, yet the casting must not be laid bare to sudden chilling.