Ken, I have seen the use of a drop of sulfuric acid in a hidden place such as the action flats to identify whether reblued or heavy patina barrels are Damacsus or not. By the way, that test sections look very nice, both in the brown and white, and black and white finishes.
Please enlighten.... What is a "rolling mill"?
A rolling mill is the machinery used to roll steel, aluminum, copper, or other metals into various shapes... depending upon the configuration of the rolls. There are many variations of rolling mills, but all depend upon some source of power to drive the rolls. The top and bottom rolls rotate in opposite directions to pull the material through the rolls of the mill. Rolling mills for pipe or round bars will typically use a series of three rolls 120 degrees apart to drive rolls which are shaped to produce a cylindrical shape. The material is fed into these rolls, and they are squeezed down under enormous pressure and typically reduced in thickness while at the same time increasing in length and/or width. In a flat roll mill, a 20-25 ft. long slab may result in a coil of flat rolled steel hundreds of feet long. The separation of the rolls is adjustable by the use of massive screw-downs that raise or lower the rolls by moving the bearing chocks on the roll necks up or down. A mill may consist of one set of rolls mounted in massive cast iron mill "stands", or multiple "stands" may be set up in series to provide several steps of reduction.
Modern steel rolling mills may develop 900 metric tons of force or more, and may be driven by a series of motors developing 10-20,000 horsepower or more. Early rolling mills used water or steam power to turn the rolls. The material may be first heated red hot to 1800-1950 degrees F, which makes it softer, so more reduction is possible per pass. This is called hot rolling of course. Cold rolling results in much less reduction, and the enormous force changes the grain structure of the steel. Cold rolled steel is usually "pickled" in acid before rolling to remove mill scale so that the scale formed during hot rolling is not rolled into the surface. Rolled-in scale is considered a defect that will also quickly dull any cutting tools used to eventually machine or cut the steel. Annealing, a long slow heating to above critical temperature followed by a slow controlled cooling, is often necessary to relieve the stresses or work hardening caused by the rolling process.
In the production of ribbands for Damascus barrels, layers of iron and steel were stacked in differing alternating layers, both horizontally and vertically, to produce the final pattern. These billets were heated to a welding temperature and forge welded into a solid mass. This process was eventually mechanized by doing the forge welding with rolling mills instead of hammers or powered trip hammers. This speeded up a very labor intensive hand forging process and resulted in more uniformity. These flat rolled strips, were then twisted and forged welded or rolled with other strips to produce ribbands which were then forge welded around a mandrel to produce a rough Damascus tube. My description of the process is very abbreviated, incomplete, and simplified for brevity. You can look at these links for much more information on this fascinating process that was used to produce gun barrels before we had the technology to make homogeneous bars of gun barrel steel and to do deep hole drilling.
http://www.damascus-barrels.com/index.htmlhttps://www.theexplora.com/the-making-of-best-damascus-barrels/http://www.hallowellco.com/damascus_twist_barrels.htm
