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Silver Casting
I have been thinking of casting a chalice in sliver in addition to making
some broach-like settings. I am set up to do sand casting and can probably finish the stuff off in the machine shop. I have a number of 100 oz ingots of .999 bulion to play with but suspect that one does not want to use pure silver for this sort of stuff. Can someone provide me with some alloying info to get something like sterling? Is this really necessary? js -- PHOTO OF THE WEEK: http://schmidling.netfirms.com/weekly.htm Astronomy, Beer, Cheese, Gems, Sausage, http://schmidling.netfirms.com |
#2
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On Fri, 16 Jul 2004 07:40:57 -0700, in ¤ô Jack Schmidling wrote:
I have been thinking of casting a chalice in sliver in addition to making some broach-like settings. I am set up to do sand casting and can probably finish the stuff off in the machine shop. I have a number of 100 oz ingots of .999 bulion to play with but suspect that one does not want to use pure silver for this sort of stuff. Can someone provide me with some alloying info to get something like sterling? Is this really necessary? js Recent threads suggest that it's pointless for us to suggest that sand casting an item of this size may be less successful than you hope, given that silver is more prone to problems with shrinkage porosity than some of the other metals you might be sand casting. But if you use plenty of sprues (or gates, if you like), and the thickness of the chalice you use as the model is not too thin, you might get sucess. And of course sand casting is easy enough to try over and over till it works, at little expense other than the silver itself, so I'd say, "go for it". Not much to lose if you've already got the setup. Sterling silver melts at around 1640 F, and you'll want it around a hundred degrees hotter than that to pour, I'd guess... Be sure to use some boric acid powder or a mix of boric acid and borax, as a melting flux, to help control oxidation when you melt. Thin sheet metal forms will be difficult to get to fill well, unless you have the metal at a seriously elevated temperature when you pour, which can increase problems with porosity. But if you've already got the setup, then it's easy enough to try, and of course, any silver scrap you generate can easily enough be remelted, or sent for refining. The alloy normally used as sterling silver is 7.5 percent copper, with the balance being pure silver. Be sure to use good pure copper as the copper source. i've always used scrap copper electrical wire, which works just fine. If you want to get fancy, there are proprietary silver alloys out there which use other than copper, in order to reduce fire scale/oxidation problems on the silver when casting. These tend to produce a softer alloy than sterling, but may be worth investigating. I don't know if they are available as "master alloys which you'd add to pure silver. suspect not, but worth asking. United Precious Metals is the main supplier I'm aware of for these alloys. As I said, the exact formula for them is proprietary, so I can't give you that composition. Hope this helps, and have fun. let us know how it turns out, will you? Peter |
#3
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"Peter W. Rowe" and the thickness of the chalice you use as the model is not too thin, you might get sucess..... I would not have given it a thought until I saw the goblet I bought on ebay. It is from Spain for what that is worth but very thick and a really nice feeling cup. I don't think there would be any problems casting it in sand other than the usual take 2, 3, etc till getting it right. If I had the notion at the time, I could have used it for the pattern but now it has rubies all over it. The alloy normally used as sterling silver is 7.5 percent copper, with the balance being pure silver..... That sounds easy enough but the other question was, do I need to do this? Would pure silver present any problems? js -- PHOTO OF THE WEEK: http://schmidling.netfirms.com/weekly.htm Astronomy, Beer, Cheese, Gems, Sausage, http://schmidling.netfirms.com |
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Jack Schmidling wrote:
That sounds easy enough Just do it, ... and you'll find out how "easy" it is. Abrasha http://www.abrasha.com |
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"Abrasha" That sounds easy enough Just do it, ... and you'll find out how "easy" it is. I was referring to the formula for sterling. Adding 7.5% copper to molten silver does not sound like much of a challenge either. As far as the whole project is concerned, I have made silver, aluminum and brass bells just a little smaller than this and the only problem I had was with the handle so I cast it separately and soldered it on later. I was planning on doing this with the stem/base of the cup also. js -- PHOTO OF THE WEEK: http://schmidling.netfirms.com/weekly.htm Astronomy, Beer, Cheese, Gems, Sausage, http://schmidling.netfirms.com |
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On Sat, 17 Jul 2004 00:19:11 -0700, in ¸ô Jack Schmidling wrote:
Adding 7.5% copper to molten silver does not sound like much of a challenge either. Rather than melting the silver and adding solid copper to it, just put both together, cold in the crucible, with the copper on the bottom (to limit oxidation), and melt both at the same time. You won't then need it to get quite as hot, as sterling melts at a lower temp than either fine silver or copper. Peter |
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Going down the casing route is good thinking on your part in view of
the soldering problems you have had with fabricating your chalice the traditional way. Sand casting will give a most unusal texture to the surface, and using 100 oz of silver would definatelly qualify the chalice for the guiness book of records. Would your mantle shelf be strong enough to take this size and weight? I can easily imagine a gallon of wine in it. Certainly nice to use. the other option would be to cast a cylinder from the silver, then turn the whole chalice up in a lathe. Fine silver turns very well. that way you would achieve the shape and size without any soldering atall. good lateral thinking. Youll find using pure silver a much better option to the traditional sterling . Ive used it a lot . I had a comission many years ago to make some paper weights in pure silver. these were 3in in dia by 1in thick. I recessed the top and fused clear enamel therein 1/4in deep then floated paillions of fleur de 'Lys on the enamel. . fired them in a kiln till the siver just started to melt. wonderful effect. Fine silver doesnt get fire scale like the 925 alloy. To answer your last question it isnt neccessary at all to alloy silver nor alloy gold. Pure silver has the most beautiful white colour. When you see sterling along side it theres no comparison. Same with gold. It has the loveliest yellow of all metals. as Peter our moderator has said we look forward to seeing the results of your continuing efforts. theres no doubt youll get the results you seek in the end. All our support for your efforts. Making broach settings are easier done by hammering the silver into a die. the bigger the hammer the better. My biggest hammer is 275 lbs. Takes some handling. I now use this minting technique a lot to make items of jewellery. Its also easy to make money this way. Id have no problem making 1pound coins (UK currency) but the trouble is they cost 2 pounds to make. Once the tooling is made(the expensive bit) the production costs are nominal. Ill give some thought to making a chalice this way, could be a new development. Jack Schmidling wrote: I have been thinking of casting a chalice in sliver in addition to making some broach-like settings. I am set up to do sand casting and can probably finish the stuff off in the machine shop. I have a number of 100 oz ingots of .999 bulion to play with but suspect that one does not want to use pure silver for this sort of stuff. Can someone provide me with some alloying info to get something like sterling? Is this really necessary? js |
#8
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"Ted Frater" Going down the casing route is good thinking on your part in view of the soldering problems you have had with fabricating your chalice the traditional way.. You know, if you unfriendly types would read my message instead of reacting to my name, things would be much more pleasant. I had not problems fabricating a chalice as I never attempted to fabricate one and never implied that I wanted to. I bought 6 of them on ebay which gave me plenty of stuf to futz around with. Sand casting will give a most unusal texture to the surface.... That's why someone invented the lathe. Sand is more than adequate for anyone other than a Troglodyte whose most sophisticated tool is a hammer. and using 100 oz of silver would definatelly qualify the chalice for the guiness book of records.... Who said anything about using 100 oz for the cup? I said I have a number of such ingots. Is it not possible just to use some of it? Certainly nice to use. the other option would be to cast a cylinder from the silver, then turn the whole chalice up in a lathe. Fine silver turns very well. that way you would achieve the shape and size without any soldering atall. good lateral thinking...... Duh! But why not cast it close to the final shape and save a lot of hogging? Youll find using pure silver a much better option to the traditional sterling ..... Ah.... finally something useful. Fine silver doesnt get fire scale like the 925 alloy. To answer your last question it isnt neccessary at all to alloy silver nor alloy gold. Pure silver has the most beautiful white colour. When you see sterling along side it theres no comparison...... So what is the point of sterling? Surely not to save a little silver. Making broach settings are easier done by hammering the silver into a die. the bigger the hammer the better..... Where does one get the dies? I can't even find decent broaches. Ill give some thought to making a chalice this way, could be a new development. You might need a real man's hammer for that one. BTW, one of my neatest cast projects was a whole set of nuts as in the bowlfull around Christmas time. I used the real nuts (walnut, Brazil, peanut, pecan, almond, etc as the patterns and cast them in pairs. I also made a small bowl to hold a complete set. Also put them on key chains and gave them as gifts. We made them in silver, aluminum and brass and won the blue ribbon, best of show and $100 at the only art fair I ever went to. We called the display Aluminart. Funny thing was, while we wowed the judges, we did not sell a single piece. That was 20 years ago and now the melting furnace is more commonly used for brewing beer but every once in a while I get the urge to melt something. js -- PHOTO OF THE WEEK: http://schmidling.netfirms.com/weekly.htm Astronomy, Beer, Cheese, Gems, Sausage, http://schmidling.netfirms.com |
#9
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On Sat, 17 Jul 2004 00:19:15 -0700, in Ìô Jack Schmidling wrote:
You know, if you unfriendly types would read my message instead of reacting to my name, things would be much more pleasant. In this instance, Jack, I think Ted was attempting a bit of satirical humor, not insult. He's impressed by the scope/scale of your projects. Most newcomers are happy if they can manage, with much help, to cast a small thing like a ring. Though I understand you've had prior sand casting experience, perhaps Ted missed that. For a beginner, just jumping into casting something the size of a chalice is rather more than a normal beginning task. Again, I'm reminded of the old adage/definition, which states that experts are the guys who know all the very many reasons why a thing is impossible, or should not be done. Meanwhile, an amateur is the guy who, not knowing a thing is impossible, goes ahead an naively does it... Sand casting will give a most unusal texture to the surface.... That's why someone invented the lathe. Sand is more than adequate for anyone other than a Troglodyte whose most sophisticated tool is a hammer. now now. Be nice. Actually, hammer work is capable of far greater delicacy than you can get with casting, even high tech methods other than simple sand molds. For one thing, wrought silver, has a much finer crystal structure without the pores and defects common to castings. The result is denser metal that's much stronger, harder, and will take a much higher level of polish. All the best holloware is made either by such methods, or on the commercial level, via spinning lathes which also start with rolled/milled sheet metal and form it to the desired shape by deforming, compressing, and otherwise working the metal the way hammers do. It's also a good way to build up strong wrists and arm muscles, as well as a good way to drive everyone in the neighborhood quite mad due to the noise... And with hand raising (as the process of developing such forms with hammers and stakes is called), you're not limited to the shapes one can turn on a lathe. ovals, varied faceted forms, and completely free form assymetrical forms are all possible. Who said anything about using 100 oz for the cup? I said I have a number of such ingots. Is it not possible just to use some of it? Certainly nice to use. the other option would be to cast a cylinder from the silver, then turn the whole chalice up in a lathe. Fine silver turns very well. that way you would achieve the shape and size without any soldering atall. good lateral thinking...... Duh! But why not cast it close to the final shape and save a lot of hogging? Again, Ted strayed into the realm of humor... Youll find using pure silver a much better option to the traditional sterling ..... Ah.... finally something useful. Fine silver doesnt get fire scale like the 925 alloy. To answer your last question it isnt neccessary at all to alloy silver nor alloy gold. Pure silver has the most beautiful white colour. When you see sterling along side it theres no comparison...... So what is the point of sterling? Surely not to save a little silver. Actually, this can be open to opinion. While fine silver has a white color, and is not prone to the oxidation problems of sterling silver, it is considerably softer. This softness, which makes many thinner forms impractical to make or use, is the big disadvantage of fine silver. for example, you might make a chalice via casting that might have a fairly delicate looking stem. With sterling silver, that stem could be thinner, and still have enough strength, while in fine silver, it would not be hard to make a stem that looks nice but would be prone to bending when used. In the case of Ted's die struck items, the work hardening of the striking process makes the silver quite hard enough to hold up. but a fine silver casting will be fully annealed. That will be a very soft piece of metal, compared to the same thing in sterling silver. Making broach settings are easier done by hammering the silver into a die. the bigger the hammer the better..... Where does one get the dies? I can't even find decent broaches. Ted actually does something here most craftspeople don't do. he uses die striking, via high pressure presses, or the old style of drop hammer (when he refers to a 275 pound hammer, it's not one with a handle that you lift with one arm, or even a normal sledge. it's likely a 275 lbs steel striking form that drops in a frame to hit a die set mounted in the base. Making the dies is the tool and die makers art. Generally one does not buy them, unless one gets lucky and finds what is needed in some old defunct manufacturers stock, or on ebay where such antique dies may be sold, etc. Gold machinery in providence R.I. has bins and bins of the old dies. Commercially, these days, much more work is produced by lost wax casting. (in investment, not sand. investment looks a lot like plaster, but takes high temps, and produces much smoother castings that you get with sand.) Ill give some thought to making a chalice this way, could be a new development. You might need a real man's hammer for that one. his 275 lb drop hammer would do it. Take a weight of that size, and drop is from a height of, say, five or six feet. Calculate the energy imparted at impact. It's quite a lot... Note that larger foms might be developed using a sequence of progressive dies, not just one single strike. |
#10
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"P.W. Rowe, moderator, r.c.j." wrote in message ... Making the dies is the tool and die makers art. Generally one does not buy them, unless one gets lucky and finds what is needed in some old defunct manufacturers stock, or on ebay where such antique dies may be sold, etc. There's a guy on the re-enactment scene in the UK who is making coin dies for historic coins, all marked so that collectors know that the resultant coins are modern copies. He's charges reasonably low prices for his dies, less than £120 (about $200) last I heard. -- William Black ------------------ Strange women lying in ponds distributing swords is no basis for a system of government |
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