Hi, Chilly. I was too interested in your content to detect any typos. Of the skills I have, typing is not one; I hunt and peck the keyboard with one finger and often mistype or double strike creating a slew of errors, but hopefully my message gets across. Yours does. Some of the more complicated things require thorough explanation, and I appreciate it. I do believe that I use the correct flux but know little about annealing, tempering, and hardening of metals -- not sure what is possible with nonferrous metals but remember having read somewhere that the Aztecs had known how to do many things that we today do not know including tempering and hardening gold so that it would retain a sharp edge. One of my greatest difficulties is removing scale and surface burns which detract from the appearance of articles I work with, and have been told that pickling would help with that, but I never do it -- don't know for sure how. What are your thoughts on those matters?
Ralph
Ralph,
If you think of steel as an example the working state, or the state where it is most malleable, is when it is heated red hot but not molten. I think that most of us have seen pictures or some example of black smithing.
Normally we tend to think of solid stuff as static and we expect it to stay where we put it. It is really funny to me, but a lot of solid stuff is in motion. Remember when you first realized that atoms are mostly space? Even though the outward appearance doesn't change, a lot of stuff is slowly aligning its internal structure to its most comfortable state. And, in the case if most non-ferrous metals, that comfortable state is hardened. They can harden by work hardening, heat can be used to change their hardness, and just sitting around can eventually get the job done.
Most non-ferrous metals have a much lower working temperature. They remain malleable at room temperature. This workable state is called annealed. When you purchase sterling silver shapes it is sold as either "dead soft", "half hard", "hard / full-hard", or "spring hard". Dead soft is fully annealed progressing up to spring hard, which is as hard as it gets. The point is that metal hardness changes. Whenever you heat it to brazing temperature either by soldering or by annealing it will soften or anneal.
When you stress metal it hardens. Hit (smite is the word we get smith or smithing from) it, bend it, or harrass it in any way and it toughens up. Stress it too much and it will crack.
Now that we have enough of the why's and how's out of the way, lets get down to brass tacks. To anneal or soften copper and silver you need heat it to plum red. I don't use the color of the metal as I find it hard to see the right point on copper and sterling silver. Rather, I use a black sharpie. I draw a swirl on the metal, heat it evenly with my torch, and when the sharpie marks disappear I quench the copper or silver in water. Then I pickle it to remove oxidation (only sterling silver oxidizes, fine silver not so much.) Copper will be soft if allowed to cool at room temperature, but quenching it catches those molecules at their most relaxed.
To anneal brass you don't need to be quite as hot. Heat it evenly until it becomes black. Then quench and pickle.
Steel is another story and I'll leave that to the blacksmiths here.
Aluminum is trickier. While the other metals I have mentioned anneal at about half their melt temperature, aluminuum anneals much closer to its melt point. To me, it looks exactly the same melted as it does hot as it does at room temperature. Rub it with a bar of hand soap. Manly soap like Dial, not soap with skin softeners. Coat it completely. Heat it slowly and, when the soap blackens, quench it in water. Clean it up in water, you don't need to pickle it. Quench aluminum fast.
Annealing makes all forming operations easier including sawing, cutting, and filing.
Almost everything can be annealed in some way to remove stresses built up in the material. I anneal glass at 960º for a varied time based on thickness and size, but usually for a minimum of 1/2 hour for small baubles. Glass is so rigid that if you don't anneal it, over time, as the glass tries to move to its comfortable point, it breaks. It can happen weeks or months after the piece is made.
PICKLINGMost stuff oxidizes. For the kind if stuff that is made with copper, it turns black. On its own we call it tarnish, when we heat it we call it oxidation. With steel it is rust and with wood and other organic carbon stuff we call it char or burnt. Wrinkles are not oxidation, they just mean our skin is bigger and isn't as stretchy as it used to be.
Oxidation -you can brush it off with wire brushes but pickling is easier. You know how we are told to remove rust with a vinegar and water solution? That is pickling. It actually does cause wrinkles on cucumbers, and we can be pickled in the tub with the universal solvent, water.
I use a mild acid pickle that I get from Naja Tools. I don't mix it quite as strong as directed to, but it takes a bit more time to pickle my work. I have an old crock pot that I picked up at a yard sale. I don't always plug the crock pot in. Warm pickle works faster. One big thing to remember is:
Do not put any ferrous metal in your pickle. Iron is more reactive than copper and will cause copper to fall out of solution, plating your stuff with a layer of copper. Replace your pickle when it is no longer doing the job. You can neutralize it with urea or baking soda (carefully) until the ph is neutral, then dispose of it. If you have used most of it up you won't have much acid left to neutralize. When I'm not needing it I put my pickle in a glass jar that seals well.
You may have heard the term "fire scale." Fire scale is oxidized copper just below the metals surface. It is hard to remove and you usually have to sand or buff it out with something abrasive. I usually avoid it by using flux, watching my heat, and by soldering and annealing clean metal.
Happy 4th of July Ralph! Your work is wonderful!
Chilly
