[Sca-cooks] Re: cast iron pots

[Decker, Terry D.]

I had to do a little research to see if my memory was functioning properly
about the Bessemer process and cast iron.

You don't use the Bessemer process to make iron, you use it to make
high-grade steel.  Cast iron has more impurities than steel including 2% to
6% carbon.  You do need a blast furnace to heat the ore hot enough to take
up the carbon.  Pre-Bessemer, the blast furnace is used to produce pig iron
which is then melted and cast as cast iron or is heated, drawn and hammered
to produce other types of iron and steel, depending on the exact process and
impurities.

A blast furnace uses forced air to improve combustion and increase the heat
in the furnace.  Medieval blast furnaces used waterpowered bellows to force
the air.  The Chinese developed the technique about 400 BCE.  It moved as
far West as Persia, but there is no evidence of further transfer into
Europe.  The earliest European blast furnace was found at Lapphytten, Sweden
and appears to date from the first half of the 14th Century.  Quite a few
more appear in the 15th Century.

So what we would consider cast iron puts in an appearance about 1400.
Whether it was used to make cookware at that time is another question.

Bear




> IIRC, what we think of as "cast iron" has a specific
> crystalline structure
> that can only be obtained using a Bessemer converter.  It's a
> good heat
> conductor, pretty strong, but it's not very malleable.  Once
> it's cast into
> shape, it'll break before it bends. (ever seen a dented cast iron pot?
> Neither have I.) Certainly the technology to cast molten iron
> into pots and
> other forms did exist in period, but the end product would
> not be what we'd
> consider to be "cast iron".
>
> Just my 2 centavos,
>
> Vicente
>