Silver pitting when annealed?

Hi! I ordered a ring a few years ago that was custom made but hated it. It’s sterling silver. I ended up training to become a goldsmith, and now I want to melt this hideous ring down and use the metal for something else. It’s a very heavy large ring so it’ll be easier to melt if it’s cut up. So I annealed it. For some reason several pits formed during the annealing, which has never happened to me before. I used the Smith little torch with oxy-propane and the multi-jet head at a fairly high temperature to anneal it because it’s such a heavy ring I didn’t want to be standing there forever trying to anneal it with a simple butane torch and figured it’d be faster. I annealed it until it had a dull even glow and then stopped. It didn’t take long. I annealed it on a magnesia block. But now it has pits in it. What did I do wrong? I’m going to melt this ring down anyway, but now I’m wondering if this is going to happen again with something I don’t want destroyed later on and want to correct the problem before I run into that situation. I would appreciate your thoughts and expertise. Thank you!

I’ve had problems with pitting in sterling silver when I overheat it. Annealing metal as you know is a lower temperature operation. Im suggesting the rose bud tip you used is best for melting and too hot for annealing. I’m happy to share with you one way to know that metal is annealed . Mark the metal with a black Sharpie marker. Put the metal in an annealing pan and draw the flame slowly from the thinnest point to thicker. (You’ll see the silver making a rainbow array of color) When that sharpie marker disappears, your metal should be annealed. Cool then quench. The metal had been softened.
Something to consider, the ring you’re annealing most probably has solder joins in it. This will affect what happens to the sterling when heated. Silver solder melts at a lower temperature than sterling silver. This might be a culprit to pitting.
If you decide to melt this ring down then it’s no longer sterling silver (925) due to the added solder content. I mention this because it can affect future operations with this metal.
Hope this helps.:smiley:

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if you’re using any gas with oxygen, the flame will be very hot…if the flame is an oxidizing flame, it will be both at maximum heat and also have an excess of oxygen that will pit by oxidation…propane air torches from the hardware store makes a flame hot enough to melt silver, but you really know when you’re are starting to overheat it. You might avoid some of the overheating by turning down the flow of oxygen to get a neutral or slightly reducing flame…
I’ve done most of my fabrication work and soldering with just a hand held propane air torch… I have a full sized oxyacetylene torch, with both cutting and welding tips… that I’ve it used for cutting steel sheet metal up to a quarter inch thick. Oxyacetylene is great for melting and pouring ingots but a full sized torch if far too hot for almost anything else. I can also run the torch on propane with the appropriate flow of oxygen…it will still be very hot.

the presence of solder, as the previous post mentioned, will definitely affect pitting. The zinc in the solder is the culprit… it will burn off as volatilized zinc oxide, leaving a small void behind.

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Flame control is an interesting subject, relative to be putting problem. I didn’t realize that the excess oxygen in an oxidizing flame will cause pitting. I’m just beginning to understand the complexity of it. I hope to learn more.

It might be helpful if you described the characteristics of an oxidizing flame. Hissy and noisy is one if I’m not mistaken. Thanks.?

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This very heavy ring might have had shrinkage porosity under a thin skin of metal, or surface defects that were peened over to make it presentable. The annealing flame then melted back some of the metal covering the holes. Heavy castings often develop pores at or near the surface when there’s not enough hot metal available to compensate for shrinkage, but the porosity from solder volatilizing won’t show itself until the whole thing is melted. Don’t worry about the pits if you’re melting the thing down, but be sure to cut out any parts with solder.

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a strongly oxidizing flame has a small deep blue pointed tip surrounded by a lighter bluish halo. It’s as hot as you can make the flame. A strongly reducing flame will have a very light blue or even dark tip surrounded by a much larger yellowish tinted halo. Hissing and noisy can be just too much gas, both fuel and oxygen even if balanced. Just playing around with the oxygen fuel mix will give you a good idea… keep the gas constant and cut back on the oxygen, or keep the oxygen constant and increasing the gas flow causes a reducing flame. An oxidizing one is just the opposite. Increasing the oxygen flow with a constant gas flow will cause the flame to “pop” out, especially with acetylene… cutting off the oxygen will cause a smoky flame that will make streamers of soot, with acetylene…

I have a oxyacetylene torch and bottles that were meant for light duty steel work. It’s too big of a flame and too hot to use on jewelry… using propane torches from the hardware store is good enough most of the time. Even though the flame is large and does not have the precision of small jewelry torches, it suffices for soldering… the trick is to know by color how hot the metal is… I do have an acetylene air torch that burns at lot hotter than propane/air… I use my oxyacetylene torch, meant for steel sheet metal working, for melting and pouring ingots… the ingot mold can be heated up a lot more quickly and hotter than using just a propane/air torch. the gold or silver melt can be superheated so that it pours evenly. For cutting steel, an oxidizing flame is used… it heats up the cut to melting and an oxygen jet activated by a lever on the handle literally burns thru the steel…the burning steel creates it’s own heat which makes cutting easier… welding with oxyacetylene and a mild steel filler is not as satisfactory as arc welding… arc welding penetrates, ensuring a strong bond. MIG uses argon as a shielding gas to prevent the weld from oxidizing. With any arc, the temperature is determined not by voltage but by current… for thin metal of a quarter inch or less, currents of 50 to 120 amps is needed to strike and maintain a high temperature arc. For thicker, 200 amps… the voltage is only 24 volts… even with that voltage, the high current generates over 5,000 degrees Kelvin or 10,000 degrees Fahrenheit. Protective clothing and a welding helmet is required. It generates a lot of ultraviolet at that temperature which can cause a bad sunburn if the skin is unprotected…

Jewelry arc welders are rated by pulse duration and joules (watt seconds)… the pulse duration is typically in the millisecond to 100 msec range, with energy delivered in the range of 3-30 and 150 joules for large expensive commercial ones…all of them have a millisecond range high voltage pulse to start the arc, followed by a much lower voltage, high current flow lasting a few milliseconds to a hundred, as adjustable, with pulse duration also adjustable… the actual current and voltage is not specified for the pulse, just the total energy applied…a 30 joule pulse at 10 volts for 100 milliseconds would imply a current of 30 amps, if I got the math right…

Does anyone out there with an arc welder have the current, pulse duration, pulse width when multiple pulses are applied, and voltage settings for an arc welder?.. not just the total applied energy per pulse?

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Thank you so much for responding! Everyone has given me a wealth of information in their posts, it’s wonderful, and I appreciate it so much!!

I am wondering if perhaps the flame was simply too hot. The ring was created using CAD. From what I understand the guy made it using a 3D printer as one solid piece without solder joins and then cast it from the resin the 3D printer created. I don’t personally use CAD, I’m not super familiar with how it works, but the ring is a pair of lips with teeth and the pitting opened up randomly across the whole of the lips, not just along where a solder join might exist if that makes sense. It’s really weird. I didn’t see or notice anything that melted off this ring when I annealed it, there wasn’t any silver left behind or that dropped off, but I did use a very hot flame. This ring is literally so big you can’t wear it because it forces your fingers apart if you put it on, there’s enough S925 in this ring to make a large cuff with, I’m not even kidding, it’s enormous. I asked for a tiny small ring and he made this giant monstrosity I can’t even wear. So I’m going to melt it down, but if I’m doing something wrong that’s causing pitting I want to know what I did wrong so I don’t destroy future things I’m not planning on melting down if that makes sense. But from what I saw of the screenshots when he was designing the ring in a program, it was made as one solid piece. I probably overheated it when annealing it, but I’ve done that before and not had pits open up everywhere. It’s very bizarre!

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So torch settings is one of the things I’m struggling with and was going to ask another question about. So get this. I have two brand new crucibles, I need season them with Borax, this is basic stuff. So I seasoned the first one, beautiful clear glassy finish, worked great. Well then I go to season the next one, and before I did I double checked the recommended psi settings for the regulators on the rosebud tip I was using, and I discovered I needed to change the settings so the propane was higher and the oxygen was lower because I had been having issues with the oxygen blowing the torch light out when I turned it up to get a strong blue flame. So I changed the psi settings to the recommended level and seasoned the next brand new crucible. And it blackened my Borax finish! Like the Borax finish in this brand new crucible is just covered in soot! I’m so irritated about this. It was the recommended setting! What happened?? Why did it do that? I’m very new to torches, I just started using an oxy-propane torch. I carefully researched it and studied up on it before I made a decision so I’d know exactly what I was doing. The problem I’m running into is when things don’t work out the way they’re supposed to, what’s the reason for it and how do you correct it? That’s what’s so hard to figure out. The troubleshooting aspect. Any idea why this happened??

So regarding this pitting and peening over it, how is that done? Like the cast comes out with pits and it’s filled in with solder? So maybe I should overheat the ring to make it pit on purpose to get the solder out before I melt it down? If solder was used to fill in holes in the original cast, I have no way of knowing where solder might be. The ring was cast as one piece, no solder joins, he used CAD to do it. Do you have advice on how I should proceed? Thank you so much for writing back, this is really helpful information!!!

Hi,
take a look at the Sunstone Orion 150 or 200i…

julie

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Hi,

If I may suggest, perhaps buy the below book to get a comprehensive general understanding of casting.

…Even though you might not be interested in doing any casting yourself, this might help to better understand your lip ring, as well as any other cast pieces you might work with in the future…

…cast metal and fabricated metal are very different…

This might help you to understand the process of metal, what happens when it melts…when it solidifies…casting, problems, problem solving, etc. such as the where/ what/ why of porosity”…”progressive solidification”…etc…

This might then help you to understand what you are seeing and experiencing.

it is a relatively short book of 153 pages, and is spiral bound.

i think reading this book will give you a better understanding…a base…before getting information, in portions, that may be beyond your current level, without a base of the fundamentals…

I found this book to be very helpful

julie

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I’ve been thinking of buying that! I’ve heard good things about it, I’ll definitely get it, thank you! I’ve been collecting and reading as many books on different aspects of goldsmithing that I can find. I considered going back to school to learn this, but… I spent 13 years in college. I’m so done. I’m just done, I can’t do it again, the odd hours, the deadlines, the teachers you inevitably don’t like, having to make things you’re not really interested in making because it’s a requirement, the stress and lack of sleep, the dreaded group projects or whatever other method of torture they drum up, etc etc. I’m taking online courses from a couple of places that are at your own pace, watching videos, taking notes, reading books, researching online, and I joined this site to talk to others about it. I want to learn everything there is to learn, but I don’t want to have to be beholden to anyone or a program, I’m just too burnt out, yanno? I’m just gonna have to flounder around and ask questions to figure this out, but you still have to get help from others sometimes. I appreciate you guys so much, everyone here has been really nice and helpful, I’m grateful that you all answer questions and give feedback. Thank you!!!

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your torch set up should have two regulators, a primary and secondary, with the secondary controlling the output pressure within the torch tip itself…the torch handle should hve two knobs controlling the air/fuel mix. The flame blowing out when burning hot with overpressure indicates that there’s not only too much pressure but also too much oxygen… the flame is too hot… lowering the secondary regulator pressure to recommended still requires some tinkering with… the knobs should allow you even finer control. A bright blue flame still is oxidizing and too hot… it’s blowing out because of excess oxygen. cutting back on the secondary regulator pressure setting gave you soot, which means there’s an excess of fuel relative to the oxygen in the mixture… use the knobs to adjust the air/fuel mixture…if you need a stronger flame, you can increase the pressure at the secondary regulator… It’s something you are going to have to work out by trial and error… don’t apply the flame to anything but observe it’s color and size… the tip of the inner cone of flame is the hottest part…the the size of the total flame is too large, there’s too much pressure at the secondary…it will hiss…if the pressure is too low, the flame will be smaller but by adjusting the air/fuel mix at the knobs you should be what you need for the job that you are doing…for lower temperatures but still a big flame, a higher pressure at the secondary, and less 02 at the knob should give you a bluish green inner flame which is slightly reducing… I had to futz around with the secondary and with the knobs using my oxyacetylene torch… to get what I needed to do what I wanted to do with the flame… oxyacetylene is a lot hotter than but the same adjustments apply… for fluxing a melting crucible dish, a higher temperature neutral flame to slightly oxidizing works best for me. For melting in metal in a crucible a big flame that is neutral to slightly oxidizing has worked for me…it got the molten silver or gold super heated for a good ingot mold pour… it also burned off zinc… injecting oxygen directly into molten silver will burn off zinc and then copper… the product is “fire refined” fine silver… fine silver absorbs oxygen and the oxygen bubbles out as it cools as “spitting silver”…
I’ve also used the same oxyacetylene torch to burn propane and oxygen. Propane is a lot cheaper… the gas flow and pressure settings are quite different… again trial and error…to adjust flame size and inner cone color…it also tends to blow out easier…both at higher secondary pressure and excess 02… acetylene is C2H2, propane is C3H8… acetylene burns a lot hotter because it has relatively more carbon per molecule and less hydrogen as compared to propane. acetylene is also two triple bonded carbon atoms. triple bonds hold a lot more energy than a single bond; the carbon atoms in propane bonded together with single bonds…the only other fuel that will burn even hotter than acetylene is coke or charcoal which is almost 100% carbon, no hydrogen but with a lot of ash…the ancients (eg. King Tut’s treasure) were able to create stunning jewelry using charcoal and blow pipes or bellows…
Propane is also a lot safer that acetylene… acetylene gas can be spontaneously explosive…the triple bonds are under a lot of bond strain and the molecule will fly part in the absence of oxygen and cause an explosion… Welding and cutting acetylene is either methyl acetylene or acetylene dissolved in a solvent with a spongy material that fills the tank… dropping a bottle or having it heat up in the sun is a no no!!!..
Propane/oxygen is plenty hot for doing non ferrous metal work…adjusting the secondary pressure and fiddling with the flow knobs is a trial and error process to produce the optimum flame for each purpose…for soldering, a slightly reducing light green blue inner flame is plenty hot enough…for melting, a hotter flame with a bright blue inner flame that is slightly oxidizing is very hot… stay closer to the inner cone of the flame when using a torch… the outer flame, if not dark or yellow, if the oxygen flow is choked down, has an excess of oxygen. Although less hot, it will be oxidizing.

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JUST FYI : oxyacetylene burns at 5,800 degrees F, oxy-propane at 4,600 F, MAPP gas (methyl acetylene
propadiene propane mixture) burns in air at 3,800 F and 1,500 higher with oxygen… propane/air burns at 3,600 F, acetylene air at 5,700 F… MAPP gas/air is expensive and I haven’t found it more useful than much cheaper propane…

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I have melted many pieces of jewelry, both silver and gold with solder joints. Unless there is excessive solder it usually comes out OK. We do this for customers who want to remake sentimental jewelry. We warn them that there might be problems because we would rather sell them new metal, but they usually want it cast with their metal. The small amount of solder in a cast silver ring is not likely to much change the alloy percentage. Probably would not even show in a fire assay.

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agree that the amount of solder is minimal… when melted, zinc burns out easily… so it really doesn’t make that much of a difference, unless, as stated there’s excessive solder with a lot of joints…

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casting is completely different from fabricating… I only did fabrication… when I needed a cast design, I did the wax and took it to a commercial bench studio to have it cast… I supplied them with the metal, especially gold to keep the cost down… casting presents a completely different set of problems… I did try vacuum casting, in a do it yourself project using suction from a vacuum cleaner… but it wasn’t satisfactory… centrifugal casting is better, but I did not buy the equipment for it…

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Dana I smile at your enthusiasm. Been there done that several times in my life on various other mediums. After getting my first two college degrees, I couldn’t see ever going back to school. Fast forward 10 years and the desire to learn a new career hit me. That meant learning that couldn’t be done online. Mostly because we didn’t have computers for general use back then. What I found going back to school was I wasn’t the normal student. I was older and had more in common with the teachers. I talked to them before and after classes. I ended up getting far more help than just attending a class and getting out of the room after as fast as I could.

Asking questions here is not as easy as it seems. There needs to be supporting evidence of what you are talking about mostly in the form of pictures. You have to be extremely thorough with your explanation of steps you did. Asking question through the computer can be a problem since people will interpret words differently than what you meant. None of us here are trying to discourage you. We want you to succeed. Conversely we can see mistakes being made, and the person asking for help refusing to heed the help. Bear with us. We can get grumpy too.

In support of live in class learning, you have immediate critique and feedback on what you did. I love workshops. I’m a geek and love learning. Problem is a 3 day or week long workshop is information overload. If you don’t have the grounding of the basics, it can be very over whelming. Thus back to the classroom I go. Over 30 years later and credit hours in college to have 5 degrees, I have most the basics. Three months verses a workshop is a boring way, but it forces you to slow down, and take your time getting the basics learned and repeated many times. Repetition is key to learning any craft.
You may not like the projects they give you to make, but there are reasons for each piece. I hated them too. Usually they give you certain things to be accomplished, but how you incorporate them into a project is just a matter of you designing the parts to fit your likes. Teachers have to deal with 10 or more students with different wants in a class. It’s like herding cats to get them all doing what is meant for that project. The teacher has 10 or more different personalities to contend with as well. In a perfect world there are no problems. In reality, even the problems you think might happen, double it and maybe you will get close to the number of problems. Many of us here have taught classes. We could all tell you horror stories of those classes. Then we have those students despite their personality quirks, shine and truly learn what you teach them. It’s a balance. Yin and Yang. It takes one step at a time to build a stairway. It takes one technique at a time to learn this trade. Don’t give up, but look at what it is you want to make. Just one project at a time. Look at the steps you need to make that project. Of course we all can tell you if your list of steps is complete. Do like in a chemistry class and write the steps down in a notebook so you have a better picture of what you need to do. If one of the steps is something you don’t know how to do, then look into what you need to do or learn to do that step. You’ll get there. One step at a time. Happy soldering!

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The pits probably were not filled with solder; that’s nearly impossible to do. If it was done, it would be impossible to get rid of in the manner you describe. However, a pitted surface can be gone over with a tool made from a shaft that’s bent over at the end and polished, so it has a hammering action when spun in a rotary tool, This mashes the surface down and obscures the underlying pits to a greater or lesser extent. If this was a “lost resin” casting, the pits could be from problems inherent to that process rather than from shrinkage, but in either case melting and recasting should not result in a reappearance of the pits, assuming you do it correctly.

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You’re a genius!! I think that must be what it was! I noticed that for something that was designed and created by a computer, it should’ve been perfectly rounded on the lips, right? But it wasn’t, if you looked closely at it, it had a lot of strange angled flat places across it that looked much more like something you would get with a hand made item than something made by a computer and printer. I just didn’t know why or what that meant. It must’ve pitted when he cast it so he peened over it. So to peen over a cast item that has some superficial pits, would you use the Foredom H.15 handpiece and one of the anvil attachments? Would that work?

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