Hi everyone,
I am going to learn to use my scrap sterling by melting it down in my kiln and rolling in my mill. Can anyone recommend a good source (reputable) for me? Ideally I’d like a comprehensive book. I know that many you tube videos exist but I’m not always sure I’m getting solid advice. Thoughts?
1 Like
Unless you are talking about an electric melting furnace, does your kiln get hot enough to do this? You should also consider the logistics of getting the melted metal to an ingot mold from the kiln. You might start with a small crucible on a whip handle that you melt scrap in using your torch. The amount of heat that your torch produced also needs to be considered. I use a propane and O2 torch with the O2 coming from an O2 concentrator for most of my work. This setup really doesn’t allow me to produce enough heat to do a good melt. I move my O2 hose over to a regulated O2 cylinder just for doing smaller melts. I use an electric melting furnace for larger melts. This is a process that takes a lot of practice and you also need to take safety into consideration. Tim McCreight’s Complete Metalsmith might be a good start.
1 Like
Hi! Thanks for responding to my query. I have Tim’s book (it was my textbook, 3rd edition) and that’s where I looked first, but he doesn’t cover it. I don’t have a torch powerful enough to do this, which is why I was interested in doing it in my kiln. I have a Paragon kiln which will heat to 2,000 degrees F, although I’ve never fired it that high. If silver melts at 1640 F, it seems like this could work. I bought a crucible from Rio. My plan was to turn off the kiln at 1700 Degrees and let it cool, then take the silver out and put it thru the mill. Now that I think about it I will also have to anneal in the kiln between rolls. I’m curious to know if there would be a difference beween bringing the silver to melting slowly (it takes my kiln about an hour) or rapidly with a torch, if that makes any sense.
Otto Frei told me once that if you heat up an electric kiln over 1500 degrees on a regular basis you’re going to kill your kiln (meaning burn out your element). People often propose the idea of melting metal in a regular kiln, but it’s not advised.
In the long run, if you don’t have a hot enough torch to melt the amount of metal that you want, you’d be way better off buying an electro melt furnace which are designed for melting silver and gold. Electro melt furnaces come in a variety of prices.
You can get a discount imported melting furnace for around $250 from Vervor.com
Here’s another one for about $600 from Pepe Tools. This one includes a video showing how it works.
There’s lots of electro melt furnaces out there in a range of prices. Every jewelry tool company sells them.
My fear for you is that in trying to save a bit of money melting metal in an electric kiln, it will end up costing you more in the long run and be endlessly frustrating.
Jeff
If you let a melt solidify in a crucible, you would never get it out without reheating it thus being right back where you started. Ingot molds are very inexpensive. My concern with your plan was that the silver would start to solidify in the crucible as you tried to transfer it from the kiln to an ingot mold. This needs to be done very quickly regardless of how you melt the metal. It also needs to be done safely. If you want to recycle scrap, look into buying a higher output torch or an electromelt furnace. As Jeff points out, there are several to choose from. You can melt small amounts of scrap in a shallow groove cut into a piece of hard charcoal. You still need a torch that will produce the heat needed to melt the metal in this groove. It will also need to be able to anneal the ingot once it cools. You have a good goal, you just need to rethink your plan to get to it. Good luck and keep us posted…Rob
1 Like
Hi,
I think Rob makes a good point…perhaps start small in a charcoal block…maybe 1-1.5 ounces…like a pencil shape/ loaf shape…you would get quite a bit of wire with that…or small pieces of sheet or strip…
Julie
1 Like
This is one of my favorite torches. It has different names, depending on where you buy it. Otto Frei calls it the EZ torch. It’s also called the Orca torch. I can melt 1/2-3/4 oz of silver with no problems.
Without a doubt the most important aspect of successfully turning scrap into usable stock is to first file and sand any imperfections in your ingot. Then to anneal, planish, pickle at least 5 times before ever touching the rolling mill. You need to strengthen the metal before putting it through the stress of rolling. Rolling out a silver ingot without it cracking can be difficult.
How to turn scrap into usable stock is a common question in the forum. There’s lots of info that you can find on this topic in the search engine that goes back for decades.
https://orchid.ganoksin.com/search?q=casting%20an%20ingot
Hope that helps!!
Jeff
1 Like
I don’t want to deny that using a traditional torch method or using an electromelt furnace isn’t a better way to melt and pour than using a kiln, but I have issues with saying that you will burn out the kiln elements by using it at a temp that will melt sterling. I have an old Satellite J-100 burnout kiln. I have looked into replacing the element, so I know it is made of Kanthal A1. I also have two pottery kilns that use the same wire elements and fire to ~2250F. The max temp for the Kanthal A1 replacement elements for the J-100 is listed as 1800-2000F. I think you could put a cast iron ingot mold with silver scrap in it into a burnout kiln like mine and let the temp go to about 1750*F, open the door and reach in with a suitable rod to skim the dross, sprinkle some flux in with a long handled spoon, stir the mix, close the door and let the kiln cool.
I don’t think Otto Frei is right about burning out the elements, if there isn’t a lot of smoke involved at high temperatures. Yes, the elements won’t last as long going all the way to 1750-1800F as using the kiln for burnout at much lower temperatures, but they are not going to be destroyed if used at this temp. Burnout temps for gold are about 1350F and for platinum, 1600*F.
Now let me qualify by saying that I bought a cheap Chinese electromelt furnace because it’s easier than using a torch or a kiln. They do tend to burn out elements quickly, too. Check the user reviews. But one could put a cast iron mold into a kiln or use a crucible and pull it out and pour immediately…it just would require more sleight of hand than I want to try to develop with a tongs to grab the crucible, skim dross, flux, stir and pour.
So I just think we should be correct in our facts and explain how it all will work. Silver is melted in furnaces in industry and you can search for discussions about this on line. They are there, I checked. -royjohn
1 Like
I don’t know much about heating elements. The one in my kiln has been there for 40 years. Melting silver in a mold placed in a kiln makes sense I guess. I was more concerned with the logistics of melting it in a crucible in a kiln and then getting it safely to the mold before it began to solidify. Let us know if someone has tried either method. Thanks…Rob
1 Like
I agree with Rob. If someone in the forum has successfully done what royjohn is suggesting please share it with us. It’d be great to know.
I was taught that ingot molds need a mold release like soot or oil and can only be warm, not hot. If they’re hot, (say over 1000F) the metal will stick to the steel/cast iron mold. Because that was how I was taught and is what the jewelry books I’ve read say, I’ve never pushed it. Maybe they’re wrong though and you can successfully melt silver in a steel or cast iron ingot mold heated to 1750+? For sure there won’t be any mold release at that temp. Again, it’d be great to know if would work.
Royjohn, thanks so much for clarifying that not all kilns are the same! My mistake. I apologize for that!
Kilns made of fire brick with exposed elements are a different beast, than modern fiber kilns, where the element is immersed in a fiber baffle. Many new burnout kilns (like many of Paragon’s) are the fiber style. I’ve replaced elements in firebrick kilns a number of times. It’s pretty easy to do and isn’t super expensive. If the element in fiber kiln burns out though you have to replace the entire baffle unit, which is 1/3 to 1/2 the cost of the kiln. That’s what I was thinking about.
Fiber kilns have a lot of advantages in they heat up faster than fire brick kilns and generally give off less outside heat. I’m sure that’s why Paragon and Neycraft have gone in that direction, but again, repair in fiber kilns is much more expensive, so protecting the element is generally advised.
All this said, here’s a confession. Once 20-30 years ago, I accidentally turned my Neycraft fiber kiln to high to burn out a flask overnight. In those days, before I had a kiln minder to control the temperature, I’d turn the kiln to 4 which would bring slowly build up the temperature to 1100 f while I was asleep. Then I would finish the burnout temperature adjustment in the morning.
Somehow I turned the kiln to high, not 4. I must have been very tired. In the morning the kiln was at 2000 f and had been there for probably the whole night. After freaking out and being thankful that I didn’t burn down my garage, I slowly cooled the kiln down to casting temperature. The steel flask was wrecked. Much of it had flaked off, which was quite surprising. I decided that I had nothing to lose and to cast the flask. The piece actually came out, but with a very interesting texture.
Now here’s the point of that story. The old Neycraft kiln still works fine with original fiber element. I did buy a Paragon kiln minder after that, but the kiln still works 20+ years later.
Sue H’s original post was asking for advice on casting an ingot with an electric kiln. Using our collective experience, we all have given the best advice that we know. But ultimately someone is going to have to try this and see whether it will actually work. My instinct is that it is impractical and probably won’t work, but it’d be great to shown that I’m wrong. In many ways, that’s what the forum is all about. Learning new things!
Jeff
1 Like
I melt my silver exclusively in an open-element electric kiln. I replace the elements once every 3 years or so and I heat to 1940° regularly. If the elements are Kanthal, they will last plenty long enough. The elements i the cheapo Vevor furnaces are nichrome and will break after a couple uses.
Either way, kiln elements are considered a consumable resource. For those of you using electric kilns you should have a spool or two of the correct size Kanthal to wind up and replace when needed.
1 Like
Is the silver in a crucible or ingot mold when you put it into the kiln? That is one of the questions being discussed along the lifespan of various elements. Thanks…Rob
So, @Monothic…you melt your silver in an open-element electric kiln. Can you say what you melt it in and what you do with it once it is melted at 1940*F?
I know that if you use a torch to melt sterling in a crucible, you would want the metal’s appearance to show liquidity and start to “spin” before you pour it. This would be, what, about 100 to 200*F over the actual melting temp? You would also need some flux sprinkled on the molten metal. You might see some dark copper oxide that came to the surface, too, right? This could be skimmed off or filed off after the ingot was poured, right? This is all true whether you use a torch or melt the scrap in a kiln, right? So I’m just trying to keep to the facts and encourage folks to keep to their facts rather than tell somebody what they can and can’t do with no empirical justification. As I said before, search for kiln melting of silver for ingots and see what AI tells you.
https://www.youtube.com/watch?v=J1DCawzrow4
-royjohn
I pre-alloy and melt in a graphite crucible that has a lid, which sits in a ceramic holder made for induction furnaces. The ceramic holder extends the life of the crucible. For pre-alloying I stir the metal with a clean graphite rod before pouring. For alloyed silver no stirring is required. I only mix clean and pure metals there is no impurity to skim off so that is not a step in the process. The pre-alloy melt gets a salt-spoon’s worth of boric acid for flux before getting heated.
You don’t want silver to be exposed to air any longer than you absolutely need to, it will absorb oxygen like a sponge. If using a torch the torch is to be kept on the melt the entire time, and for kiln or electromelt the curicble should be kept covered until the moment of pouring. I flick off the lid into a safe area with a screwdriver a second before the pour.
The temperatures I use are for my particular recipe for sterling, which is a slight modification of UPMR S57 and are higher than usual sterling.
Any slag left in the crucible gets put into the recycle bin for the refiner.
2 Likes
If your space allows, i highly recommend a propane smelter. Inexpensive and reliable heat for many projects, including forging iron and steel. I have less money invested in the smelter than my oxygen/ air torch that didn’t melt anything as well as i liked. Mine will easily melt 3 kilos of material in 15 minutes or so at a temperature high enough to keep the material in a liquid state for a smooth pour into whatever mold you want, and you don’t have to rush the pour. Again, the big drawback is not everyone has the space to do it. They aren’t any more unsafe than a charcoal or propane grill if used responsibly. With some planning they’re portable too. Maybe I’m just crazy too so there’s that.
1 Like
I bought one from Devil Forge several years ago for just the purpose that you describe. I discovered that I didn’t work on the scale needed to correctly use it so I sold it and bought an electromelt furnace. The Devil Forge furnace was well made and looked like I was lighting a rocket. Needless to say, I used out in the middle of the driveway…Rob
1 Like
Yeah now i think about it a smelter may be way out of the comfort zone of a lot of people. But after using a torch, electric kiln and smelter i still maintain my recommendation. If you trust yourself and have space enough for a grill you can do it and it’s probably overkill to be honest. But I’ve been able to confidently create with sand casting and milling and forging and grilling and I’ll never go back to the acetylene/air torch. I’m not a fan of having acetylene in the house either. Cuz y’all probably determined by now I’m some sort of weird lol.
1 Like
I I used an acetylene plumbers torch for close to 30 years. I made mainly heavy twisted bracelets and it was perfect for them. As my art ebolved, I started making smaller, finer, pieces and needed a more precise flame. I tried regulated acetylene and O2 and then regulated propane and O2, both with a Meco Midget torch. I was always worried about having high pressure compressed gas cylinders in my shop which is also the cellar of our home. After a lot of research, I settled on 1 lb. propane cylinders and an O2 concentrator. This setup with both a Little Torch and Meco Midget works great for the fabricating that I do, but it doesn’t produce enough heat to do a large melt. I then went to over kill and bought the furnace, as previously mentioned, I sold it and have settled an electric melting furnace for larger melts and will occasionally drag in a regulated O2 cylinder to do a smaller torch melt. If I ever get into doing larger brass or copper melts, I will definitely get another furnace. With the direction that the price of silver and gold is going, this may happen sooner than later…Rob
1 Like
I’d like to add that some alloys require very precise heating. A difference in 10 degrees C can have a wildly different result. For example casting 18k rose gold.
I also notice that a change of a few degrees C for my silver casts can result in pieces not filling, or coming out black with poor surface quality. A torch just doesn’t have the precision or consistency to achieve this unless you’ve been using one for years.
1 Like
rxmexiner
I have no idea why your propane oxygen concentrator set up isn’t hot enough to melt your metal in a crucible I use mine all the time you do need a multiport rosebud tip I use the Smith little rosebud tip and it works beautifully