Iron ore
In cast iron sulfur promotes the formation of white iron. As little as 0.5% can counteract the effects of slow cooling and a high silicon content . White cast iron is more brittle, but also harder. It is generally avoided, because it is difficult to work, except in China where high sulfur cast iron, some as high as 0.57%, made with coal and coke, was used to make bells and chimes . According to , good foundry iron should have less than 0.15% sulfur. In the rest of the world a high sulfur cast iron can be used for making castings, but will make poor wrought iron.
Window shutter hardware
Wrought Iron - literally "hammered" iron. Early on, billets of cast iron were transferred to iron forges. The cast iron billets were heated to near-molten and flattened under a heavy water-powered drop hammer - kind of a see-saw with a couple of hundred pound chunk of iron "hammer" on one end of a heavy wooden beam and a rotating wooden cam acting on the other end to lift and drop the hammer in time with the turning of the water wheel. Valley Forge took its name from a small shop such as this which the British burned, unopposed, on their way to Philadelphia in 1776. Once hammered thinner and longer the billet would be doubled backed on its length, re-heated and re-hammered. This repeated exposure to the oxygen in the fire and the compressing blows of the hammer would burn and drive impurities from the billet. The iron being forged would become increasingly malleable with each heat to which it was subjected. The finest forging iron was multi-layered and nearly pure iron. To the best of my knowledge, there is no new wrought iron being produced today. Well, maybe Japanese Samurai swordsmiths still make their own – but if it's in Home Depot and says "Wrought Iron" it isn't.