Wrought iron has a “fiber,” as may be seen from two of the illustrations presented. In “coming to nature” small particles of iron crystallize out as they become purer. These measure perhaps ¹⁄₃₂″ or ¹⁄₁₆″ in diameter. As it goes to the squeezer the ball of “sponge” is made up of such grains of iron loosely welded together with the interstices filled with cinder. The squeezer, and later the rolls, elongate the particles of iron into threads, which, welded together, make the bar.
It is thought by some that films of cinder, too thin to be seen under the microscope, surround each fiber of iron and that these afford protection from rusting and give to wrought iron the excellent welding quality that it possesses.
Drawing One of the Balls from the Furnace
On the Way to the “Squeezer”
Steel has no fiber and for this reason it cannot be split as was the wrought iron bar shown in the illustration of page [92].
It will have been noticed that only small amounts of iron can be refined at one time. This, indeed, has been the unfortunate part of wrought iron manufacture, for it may readily be seen that production of any such material in lots as small as a quarter ton results in labor costs which are almost prohibitive in these days of machine-made goods. Not only is the output of a furnace small but much skill and judgment are necessary for the production of a high grade product. Very sturdy and strong men, too, are required as puddlers, for the work is heavy and the extremes of heat and cold to which they are exposed necessitate men of rugged health.
Cross-Section of a “Squeezer”