metalsmith
Cave Dweller
Member since October 2012
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Post by metalsmith on Dec 23, 2016 14:13:21 GMT -5
I've been asked a question about silver-smithing. I figure it is best to discuss this on the forum then others can contribute / learn from it too.
Question:
The problem is with silver: I measure very carefully, several times, and make sure the stone fits the bezel properly before the final solder to the base. I'm thinking when i added the twisted wire decoration it pushed too hard into one side of the bezel, thereby making the stone very difficult to set. But I've had this problem even when not using a decoration. At the end, the stone barely fits. I don't understand. Does the silver shrink or stretch after it's finished? Does pickling do anything? It's really confusing.
My other (main) problem is getting solder to melt! On some things, it melts right away and on others it won't melt at all, no matter how long I throw fire at it.
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Post by Pat on Dec 23, 2016 14:17:47 GMT -5
Re solder melting: solder flows to the heat. First the solder melts, then it flows which is what you want. Don't put flame on the solder itself.
I don't know about the shrink problem.
Good luck!
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metalsmith
Cave Dweller
Member since October 2012
Posts: 1,537
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Post by metalsmith on Dec 23, 2016 14:51:50 GMT -5
Question: I'm thinking when i added the twisted wire decoration it pushed too hard into one side of the bezel, thereby making the stone very difficult to set. But I've had this problem even when not using a decoration. At the end, the stone barely fits. Does the silver shrink or stretch after it's finished? Does pickling do anything? It's really confusing. My other (main) problem is getting solder to melt! On some things, it melts right away and on others it won't melt at all, no matter how long I throw fire at it. These questions are pretty common. There's no doubt about it, silver soldering is - or can be - quite fickle. Most of the advice remedies below are the result of experience (i.e. doing it wrong and finding out what it was!) Normally the stages would be (simplified to) prepare, solder, quench, pickle. Many of these stages are optional. If you know your metal is clean, much of the preparation can be dispensed with. Depending on the metal being used, it may even fuse without the need for solder. Rather than quench it, it can be left to cool. Rather than pickle, it can be polished clean. But ... generally speaking there are a number of components of the four stages described above that can help. Cleaning should remove any visible matter as well as invisible oils from the piece. I suggest you start with washing your hands with soap to remove grease that forms part of your skins normal breathing / lubrication to keep itself soft. The metal should also be clean. I've soldered silver straight from under a plastic wrap without cleaning, so the adhesive didn't seem to cause problems. If it is not pre-wrapped and you don't know its history of handling then it should be cleaned. If it is just a matter of oils then soap and water should do the trick. If it is more than that, then you should take steps as appropriate, from a light scouring with a clean (or at least dedicated to silver) pad to a fine sanding paper. Sorry, but the prep hasn't finished there. I've narrowed some of my problems down to historic handling of my solder. I tend to use fine silver-solder wire but I've also used silver solder powder. Fluxing is part of the prep stage. There are choices again, but I tend to use Borax which I grind from a cone. This should be milky white and opaque, but I've used translucent, watery fluid successfully. I've also on occasion found this to be one of the problem issues. The length of time the flux should be left depends on the strength of the flux. I apply it with a dedicated paintbrush or two, depending on how fine the application is. After cutting a tiny snippet of wire, (I used to flatten it to stop it rolling around - but take care that the equipment you do this on is clean!) Unless there is need to stop it rolling, now I use a finer wire, I just position it with the flux paint-brush. This implicitly fluxes the solder too. It can be positioned reasonably with the paintbrush, but I'll use a titanium soldering probe (I made) to fine position it. Soldering is a matter of: - Joining metal surfaces: for this to be effective the metal surfaces should be parallel, clean and close. Either fine-filing or cutting down the join with a piercing saw should help with this. Tension the metal if needed so that when it is cut, it will simply press closer together. Re-flux the cut. It will run down the seam - don't pull it apart again.
- Bringing the metal to temperature. Don't put the flame on the solder - instead, heat the metal. The pieces being soldered should be at the soldering temperature (see your technical data - it depends on the grade of solder). If there's a substantially bigger component, heat that and the smaller piece will come up to the heat. If your joining a ring, heat the ring away from the join and then bring the hot area towards both ends - the join by running the flame around the ring.
- Watch the colour temperature of the metal. After cherry red, it should turn orange. A moment before the solder runs, the flux should impart a silvery appearance to the metal. A moment later and the solder should now run. Capillary forces will entrain it along close joins. After elevating the temperature slowly to start, this should be done quite quickly.
Take too long and yes, in my experience, shrinkage will occur. This is generally because the metal temperature gets elevated too high causing some of the silver to start to melt and sublime. Quenching helps to prevent porosity bubbles that might reduce the strength of the silver, so this is generally advised. Quenching 'freezes' the state of the metal at the time of the quench - it captures the high temperature state and preserves malleability. Maybe this is what happened when you say you may have 'pushed too hard into one side of the bezel'. I've done this myself, for sure: sized and shaped the bezel nicely then in transferring it to the base-plate, I scrubbed it on a 1200 grade diamond pad to get a close seal; in doing so, just shifted the profile slightly. Options here might be 1) scrap it and start again, but that would be a waste of effort. 2) take a little off the stone 3) make / buy another stone. Pickling cleans, but shouldn't be the source of changes in size. HTH
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Post by orrum on Dec 23, 2016 14:55:13 GMT -5
Drink more beer.
No try heating the bottom of the back by laying it on a tripod with screen. When you think it is hot enough around the outside of the bezel on the bottom quickly, let me stress quick bring the torch to the top and put the flame in the middle of the bezel. The solder should flash melt and shoot to the bezel where it's hotter.
Also you might need a larger tip in order to get enough heat. I solder the bezel to the backing first. Then I put the rope edge etc around the bezel and solder it from the outside by using the heat to draw solder from the bezel plus I pic solder a lot of trim like prongs, cups etc. Also use a bunch of flux, not enough flux will cause fire scale and also not let the solder run smoothly. Hope this helps.
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metalsmith
Cave Dweller
Member since October 2012
Posts: 1,537
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Post by metalsmith on Dec 23, 2016 15:00:44 GMT -5
Re solder melting: solder flows to the heat. Great point. If you might allow me to be very explicit with this, Pat: The solder melts and flows towards the hottest part of the metal. So there is an oxymoron with my early point of not heating the solder directly. Some pieces can be heated from underneath. Alternatively, heat them to cherry red and the 'flowering' then to the silvering of the flux, then gently turn over the piece and the solder should stay in place. Once the solder melts, use the torch to create a hot point for the solder to follow then you can draw it forwards around the join. At this point, be careful with different thicknesses not to cause thin bezels for example to go into melt down. I think that regular soldering is an important exercise to keep control on these many minor points where things can go wrong. Practice makes perfect and I find that if / when I take a break from it then I'll inevitably have a few 'learning examples' before I smooth out the creases again.
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metalsmith
Cave Dweller
Member since October 2012
Posts: 1,537
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Post by metalsmith on Dec 23, 2016 15:11:13 GMT -5
1) Drink more beer. 2)Use a bunch of flux, not enough flux will cause fire scale and also not let the solder run smoothly. 1 - definitely doesn't help, but you might feel better for it 2 - My preference is to only use adequate flux. Too little is too little, so it must be adequate. Typically I'll liberally coat e.g. the 0.5 or 0.33mm width at the bottom of the bezel and this is enough, together with the minor shift from coarse to fine placement. Firescale is easier to sort out than Lake Solder... To protect areas you don't want either firescale or solder, consider using a paste made of rouge or a product such as firescoff. Alternatively, after quenching gently heat the piece back to cherry red to redistribute the copper. A good pickle - but not too much or this will dissolve the copper out of the solder and undo all your good work - and polish.
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icatz
spending too much on rocks
Member since October 2015
Posts: 453
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Post by icatz on Dec 25, 2016 8:13:46 GMT -5
Good advice. Thanks everyone.
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TRG
starting to shine!
Member since October 2016
Posts: 31
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Post by TRG on Dec 27, 2016 21:50:51 GMT -5
Great tips! I don't know if any of you have tried it but I never went back after I learned due to the results. Before soldering in addition to soaking in the pickle, I put the metal in a small glass jam jar with a spoon full of boric acid to half jar of denatured alcohol mixed together. Once you have it made up it will last for a month or 2. After a short time take out the metal and put onto the soldering block. ***Make sure the jar has the lid on and is far away from the torch.*** Then put the torch to the metal for a second to light the alcohol and a green flame will burn for a few seconds. After it goes out, apply the flux as usual and go about soldering as you usually would. This cleans the metal way better and although it's an extra step I never have the same soldering issues I once did. For how the solder flows now and follows the flame with ease, I just stick to this routine now with what these jewelers taught me. To solder and get the flame underneath I take 2 soldering blocks side by side to an open V shape or tunnel so that I can balance the metal on the sides. Be careful how far apart you balance the metal as the metal will want to droop and sag with too much heat underneath. I too mostly heat the bottom metal first and then when the flux goes clear I start to place my solder chips while giving it a pass with the torch to keep the temperature up. When their all in place I heat the bottom again quickly and bring the flame up top and it's almost like drawing with the torch flame where you want the solder to flow. It goes quick that way. If you just blast the top of the metal with the flame it makes the solder want to travel upward and ends up all over the bezel etc. Where to balance them both out you avoid risks like having a flame on a bezel for too long. I found by heating underneath the main piece of metal heats everything else up to where you barely have to hit it with the torch.
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