I will begin with an explanation of damascus steel and the methods used to create it. Once I have established the basic understanding of what damascus steel is and how it is made, I will circle back to answer your specific questions about it. Be patient; this could become a very long thread.
The making of pattern welded damascus, is the purposeful manipulation of layers of chemically different materials to create a pattern in the surface of a finished product. The patterns are made by manipulating edges of the layers to the surface of the finished piece where they will form a predefined pattern. As the elements are chemically different, they will be differentially affected by etchant and/or patina solutions to make the pattern visible.
The very simplest of damascus begins as a stack of flat materials. Typically, of alternating layers of two chemically different types of steel, or of steel and iron. The stack is forge welded into a solid mass, producing what today in the US, is commonly called a billet. Older terms were faggot and lopin, and I'm sure other names in different parts of the world. This billet is then drawn out by forging, pressing and/or rolling, into bar stock.
It is entirely possible, by very controlled dimensional reduction to maintain the layers in their original flat arraignment. The resulting pattern will be of simple straight lines. As there is little aesthetic appeal in a straight line pattern, the material is typically manipulated to displace the layers relative to their original positions in the billet. This is often done by mechanical manipulation, or a combination of stock removal plus mechanical manipulation. In the damascus pattern that we today call "random pattern", the mechanical manipulation is simply from the impact of the hammer on the layers of material. Each hammer blow displaces the layers and results in a circular pool shape in the surface of the finished piece. Overlapping hammer blows create overlapping pool shapes, the final appearance having what many call a wood-grain effect.
More purposeful manipulation of the layers can be accomplished by twisting, forging at an angle to the arrangement of the layers, stock removal by cutting through the layers and then forging the stock flat to raise the cut-through layers to the surface, or by pressing the layers with pattern dies to raise layers into the die pattern and then grinding of the raised areas to expose the upward turned edges of the layers. The billet can also be cut into angular sections, that are then restacked to organize the layers of material into a specific pattern. The restacked segments are then forge welded into a solid billet. The patterns possible are absolutely endless. Many modern damascus smiths who specialize in very complicated patterns, use "Play-Doh" to plan for the creation of damascus patterns. Using different colors of "Play-Doh" they can formulate a manipulation process to create specific patterns in steel.
Another form of damascus pattern creation is what we today call mosaic damascus. In mosaic damascus, elements are stacked in an arrangement to create words or pictures. The picture that Pete posted of the rampant lion, is an excellent example of early mosaic damascus (thanks Pete!!). The lion was created by stacking small square rods of material together, then surrounding them with rods of a different material. This stack then being forge welded into a solid mass. To make assembly and welding easier, these arrangements of materials to create pictures and words are typically much larger than will be desired in the finished product. Once welded together, the stock will be dimensionally reduced as evenly as possible, so as not to introduce distortion in the design. After a degree of size reduction, the design is often stacked into another assembly of elements, to again be forge welded into a solid mass for additional reduction to a dimension suitable for use in the finished product. In this way, a picture, such as the rampant lion may be assembled with an original dimension of perhaps 3 inches tall. It can then be dimensionally reduced to the size of a pin head for use in the finished product.
Early mosaic damascus was typically assembled from square rods , or other dimensional stock; as seen in the rampant lion photo. Modern mosaic damascus is often made by using water jet or EDM machines to cut out the shapes. Nickel is often used for the primary shape in modern mosaic damascus, as it resists the etchant solution and will display prominently when surrounded by high carbon steel. The primary design shape can be placed into a perfectly fitted hole, cut into a section of high carbon steel by the same water jet or EDM process. This assembly is then forge welded together. Or, the primary shape can be placed into a steel container, such as a piece of pipe, then powdered steel is poured around the primary to fill the container. The container is then sealed and forge welded into a solid mass.
To be continued…………
