I wonder if a section of wrought was heavily drawn like in a classic barrel if the look would start to change. In Doc Drew's barrel pictures that distinguish wrought iron from steel, the strand appearance of wrought seems to changed to a 'string of bb's' appearance. The slag/silica components seem to be reduced in overall percentage of the wrought, and well surrounded and distributed in the iron.
I've always wondered if the extensive drawing and other working of damascus barrels was to minimize the effects of the inclusions and defects that the early smiths knew were in the raw starting materials.
The silica would definitely be changed, once made into a barrel tube. Coming out of the reverberatory furnace, the silica is in globules within the iron. During piling and drawing out into bar stock, the globules become long strings. Each occurrence of drawing the bar out, lengthens and thins the strings of silica, as well as works some of the silica out of the iron. Piling, welding and drawing out of the wrought iron is continued until the bar stock retains the desired amount of silica content. There were many grades of wrought iron, each containing a certain amount of silica as was desired for the end use of the material.
After the wrought iron is used with steel to make a riband of damascus, the welding, drawing and twisting of the rods will have made innumerable changes to the shape and size of the silica strings. In looking at a micrograph of a damascus barrel sample, there is no way to know at what angle you are viewing the silica string inclusion. Is it from the side, at the end, or at some angle to the directionality of the string? The view from a single plane, doesnt tell you much about the overall shape of the inclusion.
The extensive amount of drawing out and manipulating the damascus for barrels was much more about creating the desired damascus pattern, than it was to control the silica inclusions. I believe that the use of wrought iron, with its silica content, was to facilitate the forge welding process. As well as it made the damascus steel softer under the hammer and easier to shape into a barrel tube. Im certain that they had a preferred silica content for the raw wrought iron material, specified to facilitate the welding and shaping work. But the end result of the silicas condition in the finished product was very much left to chance.
