[TheForge] Fwd: bog iron/pig iron to wrought iron

[Andrew Vida]

Daniel Kretchmar wrote:
> Greetings,
>          A few months back I participated in an iron smelt at the home
> of Stewert Stone in Ripon, WI.  He built the furnace out of clay and
> pulled out a sizable bloom.  A bunch of us (SCA blacksmiths) heated up
> the bloom in a stone forge and pounded it into managable ingots
> 
> .....Now a question.  I took the ingots home and I have used my JYH
> Tire hammer to pound it into bar stock but somewhere I remember
> reading that I should fold and weld it several times to convert it to
> wrought iron............Can anyone help me out here?  What's the next
> step?

	Drawing and rewelding comprise the process of refining.  As it comes 
out of the furnace, the bloom is worthless.  There are numerous voids in 
the iron, much of which is filled with slag.  The purpose of drawing the 
bar is twofold.  It alters the bloom into a useful form (bar, sheet, 
etc.) and also it drives out the excess slag.

	As the slag and the iron are drawn, they intermingle with each other, 
forming long threads of iron and iron silicate which orient themselves 
parallel to the direction in which the bar is being drawn and resulting 
in an almost wood-like structure.

	After the first drawing, most of the slag has been forced out, but much 
remains.  The grain structure is coarse and under the hammer may have 
some rather undesirable characteristics, such as splitting like wood 
when forged at anything less than bright yellow heat.  Such iron is 
called "muck bar" and is good for many applications, but not all, e.g. 
the creation of fine architectural work including gates and window 
treatments, or furnishings such as tables, or utensils such as forks.

	Nicking the muck bar and rewelding/redrawing results in a 
single-refined iron.  Such iron will be a bit more forgiving than muck 
bar in terms of temperature, but not so much.  Nevertheless, it has its 
uses - e.g. some of the simpler straight elements in a garden gate such 
as uprights.

	Another reweld/redraw produces double-refined iron, which has yet more 
slag forced from it, a finer grain structure, and is therefore a finer 
product.  Such iron may be suitable to the decorative elements of that 
garden gate including scrolls, leaves, animal figures, etc.

	Yet another reweld/redraw results in triple-refined wrought iron, the 
highest grade commonly available.  This iron is very fine-grained, far 
more forgiving in terms of cold-shortness, and would be used in the 
production of the finest items such as instruments, tools, household 
utensils, etc.

	There was another grade that was finer yet and that was called king's 
bar.  There is not much in the literature about it, save to say that it 
was the finest iron available, was very costly, extremely fine-grained, 
and not very common at all.

	That's wrought iron refinement in a very small nutshell.  I hope you 
find this marginally helpful at the least.

	Regards,

	-Andy