You read in Part 1 about the materials and technique required for making your own damascus. Now listen up for some additional techniques as well as important problems to avoid.
Patterns are unlimited, but remember that whatever pattern is developed will not show up until the piece is etched. For etching I use ferric chloride. Ferric chloride is the best and safest etchant for the metals I use. Etching will give a good idea of what you have created in all your hours of hot, dirty work, but the pattern won’t really pop until the piece is properly heat-treated and finished.
If you have never made pattern-welded Damascus before, the odds are you will have some problems, but the good news is they can be solved.
For example, inclusions are usually small and are something that was trapped between the layers during the welding process. Most likely, they are scale or pockets of flux that weren’t driven out due to poor technique when making the weld, or they could be dirt from leaving grinding dust between layers.
It doesn’t matter what they are, but what matters is that they ruin the look of the piece, and the way to avoid having them is to be fanatical about your weld surfaces. Weld surfaces must be clean and either dead-flat or very slightly convex, (never even slightly concave), as well as free of divots. I grind and wipe clean my material before each weld cycle. I know many who feel this is a waste of time and labor, but I almost never have an inclusion. Since I’m furnishing material for others, I can’t afford to have bad metal out there.
Even if I were making steel for my own use, I still would spend the extra time to keep everything clean because who wants to get almost finished grinding a blade and have an ugly booger show up? This involves some heavy grinding between forging cycles and welding cycles, and the work would be much faster if I just cut and folded depending on the flux to work miracles. I think it is worth it—after all, you are doing the whole exercise to create something special, not “something special except for that small black spot near the tip.” I think etching a little deeper to blend a booger is also unacceptable.
Another common problem is having blisters pop up on the surface of the billet. I think these come from leaving low spots on the surface of a layer. When the weld happens around the low spot, whatever air or flux is in the low spot is trapped, and then later, when temps are high, there is enough boiling or expansion to cause a blister. Sometimes blisters happen when using thin material in the initial stack and the only way I know to avoid that is this—put thicker layers on the outside and clamp the stack tight before placing the arc welds. We use arc welds to hold everything together until the first forge weld is completed. To deal with blisters after the fact, some people center punch and flux and go back for another welding cycle. When I had blisters early on I found it best to grind them completely out. Either solution can compromise your final pattern a little.
Another good thing about heavy grinding after the forging cycle and drawing out is that sometimes there can be blisters you failed to notice as a dark spot on the metal during forging, or that don’t rise.
If a spot like this was missed earlier in the process, during heavy grinding it will glow red because it is so much thinner and is insulated from the surrounding material. It is much better to deal with it rather than putting it back in the center of a billet during a fold or re-stack.
A common problem with beginners is simply a bad weld. They can be the result of temperature being too low while trying to weld, missing a place when setting the weld (hand hammer or power the blows needed to overlap), flux not reaching an area, starting a weld sequence when the outside is hot enough, but the inside of the billet is not, or just dirty work.
Normally the billet is worked square. If you ever have a question about how good your welds are, turn the billet on the diamond and work it. If the welds are good, the piece should forge like a solid bar of steel. If they aren’t, it will come apart. You want to find poor welds as soon as possible, and deal with them or scrap the piece before more time is invested.
A less common method of creating a pattern-welded piece is working with pieces of steel and/or powdered metal enclosed in a steel container. Some of the advantages include: fewer limits on what can be done in design; the powdered metal allows for working with odd shapes; if done correctly, perfect, solid welds.
The disadvantages I’ve found are the extra work in setting up the can correctly, long soak times that mean extra fuel usage; powder is expensive; powdered metal can be hard to find; removing the sacrificial container can be labor-intensive; the piece often requires accordion cutting (which is also labor- and time-intensive. The best thing about “working in a can” is there is a variety of things that can be done in the metal that aren’t possible with normal methods. [Editor’s note: We are hearing that there are significant health risks in improperly handling powdered metal. Top-quality respirators are essential. Be sure you understand the safety procedures and health dangers before you open a container of powdered metal.]
If you have the tools and don’t mind hot, hard, dirty work, try pattern welding. You might become as captured by the subject as I am. Work hot, keep your work clean and try new things.
By Matt Walker