By Shawna Kulpa
One lesson we’ve learned from the COVID-19 pandemic is the importance of rolling with the punches and knowing how to make do. If you have to close your workshop due to government restrictions, you learn to have Zoom meetings with your team from home. If you can’t have customers in your store, you learn to master online selling. And if you need metal sheet or wire for a job and your metal supplier is shut down (or can’t get product shipped out to you in time), you learn how to make your own.
To help you master the technique of making sheet and wire in your shop, we’ve compiled a collection of best tips and techniques from some industry experts. They’re sure to have you cranking out stock metal supplies in no time.
• If you’re going to make your own sheet or wire from scratch, most experts recommend that you use master alloys from your refiner or supplier. While it is possible to mix your own alloys, the time and research needed to make sure you have the proportions right, as well as the hassle of errors if you get them wrong, far outweigh any benefits.
• The basic process of making your own sheet or wire isn’t complicated: you melt metal, pour it into a mold to create an ingot, then roll that ingot into the form you want. That’s why, when ordering a master alloy, be sure to specify that you want a rolling alloy, not a casting alloy. “Most casting alloys have grain refiners, which help with the fluidity of the gold,” says Gary Dawson, owner of Gary Dawson Designs in Eugene, Oregon. “Those [refiners] tend to make them more brittle, less roller friendly.” In a pinch, you can roll a casting alloy, he adds, but you won’t get the best results.
• Since you’ll be working with molten metal, you’ll need to take some safety precautions. “A leather apron and heat-resistant gloves are essential,” advises Jo Haemer, a jeweler and educator in Portland, Oregon. “Do not wear open-toed shoes or flip-flops. Goggles are okay for melting silver and gold, but if you’re working with platinum, you’ll need to wear #10 or higher welding goggles to protect your eyes.”
• Ideally you should use fresh metal for this process. If you do recycle scrap metal, make sure it’s as clean as possible from the beginning. “Make sure you remove all solder,” warns Dawson. He notes that if there is a problem with the reused scrap, it’ll usually show up as cracking pretty early in the milling process. “When you’re reusing older metal like that, be prepared for a failure because you can’t control the alloy. You don’t really know what’s in there unless you made it to begin with.”
• A lot of success in this process comes down to the ingot mold used. While you can create your own by carving a trough into a charcoal block, you’ll likely get more consistent results by using a metal mold.
There are generally two styles available: an open horizontal mold and a closed vertical mold. At first glance, the horizontal mold may appear to be the easier option—you simply pour the metal into the mold through the wide open top. However, the vertical mold delivers a more consistent form. Because the top of the horizontal mold is open, the exposed metal can take a different form when it cools. It’s similar to baking a loaf of bread—all of the sides enclosed by metal will take the shape of the mold, but the top won’t necessarily have a flat surface.
Much of the success in pouring an ingot comes down to the type of mold used. Although there are several varieties, closed vertical metal molds, tend to deliver the most consistent forms.
• To prepare the ingot mold, you’ll need to apply a coating that will act as a barrier and prevent the molten metal from sticking to the mold. Some jewelers use a 3-in-1 oil or sprue wax, but Dawson prefers to use soot from an acetylene-only flame. He notes that the soot from a wax candle will also work.
• Plan to heat the mold before pouring the metal into it. “Pouring hot molten metal into a cold or damp mold is dangerous and can lead to metal exploding out from it, as well as cold and partial pours,” warns Haemer. Expect to heat the mold for 5 to 10 minutes, depending on its size.
According to Dawson, the mold doesn’t have to be red hot, but it should be too hot to touch.
• If you’re new to using a vertical ingot mold, it couldn’t hurt to practice pouring liquid into the mold’s small opening. “A great way to practice is with your scrap metal,” says Daniel Ballard of Artistry of Gold in Los Angeles. Finding the right rate of flow will take practice, he adds: “If you pour too quickly, it spills. If you pour too slow, you can have a problem where you won’t get one solid mass that froze up together.”
And don’t worry if you don’t get a good pour even after a few practice tries. “Relax and just melt it down again,” says Haemer. “I expect it takes most folks a good 6 to 10 pours before they’ve mastered the technique.”
Pouring the perfect ingot takes practice. Experiment with melting and pouring scrap metal to find the right rate of flow to ensure a good pour.
• Once you’ve successfully created an ingot, you’ll want to clean it up before putting it in the roller. The surface of the ingot may need only minor polishing, but the edges will likely need more cleaning. “Grind them a little, as any flashing could be a source of cracking,” says Ballard. “Trim up the edges before going to the roller.”
When cleaning the metal, use a wet and dry grinder or wet sandpaper to prevent overheating the metal and to control the filings. “The water will take the heat away and the filings will go where the water drips and you’ll get all of them back,” says Ballard. “Don’t overheat the metal. It’s ok to get it warm, just don’t let it get hot. It makes the metal brittle.”
• In addition to cleaning, some jewelers like to forge the ingot before starting to roll it out. “This will keep the ingot from cracking at the edges while you’re rolling it,” advises Haemer. She typically uses a lightweight sledgehammer with a polished face. “I recommend fully hammering each surface at least four times. Once you’re satisfied, anneal, pickle, clean, and dry the ingot. It’s now ready to roll out.”
• Before rolling out the ingot, inspect the rolling mill rollers closely to make sure they’re clean and shiny. “Every little line, flaw, and dent in the roller will be faithfully reproduced in the sheet,” cautions Ballard. “The prettier the rollers are, the prettier the sheet.”
• If you expect to be making a lot of your own sheet or wire, you may want to consider investing in a power rolling mill. Although they’re more expensive than the traditional hand-rolling mill found in most jewelers’ shops, electric mills can often be found on the second-hand market at a discount. “If you’re going to do a lot of this, get an electric mill—your arm will thank you for it,” says Ballard.
• While it’s important not to attempt big reductions in a single pass as you roll out the ingot, beware of taking too many small reductions. “If you roll it with too many tiny bites, you run the risk of the outside of the metal hardening and the inside remaining softer,” says Ballard. As the outside and inside are slowly squeezed together, this can lead to cracking.
• As you reduce the sheet, you’ll want to periodically anneal it. Haemer likes to “anneal the metal after reducing the thickness by one third to one half,” whereas Dawson aims for a 20 percent reduction for the first roll and then 50 percent reductions between annealings. Ballard, however, believes that jewelers should take a trial-by-error approach to find what works best for them. He recommends jewelers learn to feel the differences in the metal, which will help them to master this technique, and that’s something that will come only with experience.
“The metal will tell you when you do something wrong,” he says. “It will crack or take a big turn coming out of the mill instead of going straight. When it feels different, it’s time to anneal.”
Before rolling, metal ingots should be cleaned. Although the ingot surfaces may need only minor polishing, the edges should be trimmed, as any flashing could lead to cracking.
• Regardless of your annealing schedule, it’s a good idea to roll the sheet in only one direction between annealings. “After an anneal, you can change the direction,” says Dawson. “Rotate it 90 degrees.”
• Keep a close eye on the metal during the rolling process, as tiny cracks may start to appear. “Look at it closely, even with a loupe,” says Dawson. If tiny cracks do appear, you may be able to file them out of the surface of the metal. “In some cases, you can heal cracks by heating the metal to the state before it becomes fluid and the cracks heal. You then quench it to anneal.” But he cautions that this technique doesn’t always work. “Sometimes you can get away with healing cracks, and sometimes you can’t. Sometimes it’s better to pour another ingot and try again.”
• Avoid pickling the metal until after you’re done with the rolling process. “There’s always micro-porosity in the metal,” explains Dawson. “If you quench it in pickle, it’ll suck up pickle into the micro-porosity. The mill will then squeeze it out and it can make pits in the rollers.”
• The process of rolling wire and rod is similar to the process for sheet. However, you want to make sure you rotate the metal to prevent wings from developing as metal is squished out the sides of the slots on the rolling mill. If these wings occur, “immediately go to your bench and file them off before doing any more rolling,” advises Dawson. If not, “subsequent rolling will push the wings down, but [now] they’re separated [from the main stock] and will make slivers that will curl. Those slivers of metal can sometimes go through the whole finishing process and then come off, leaving a very undesirable channel in a finished piece.” He recommends rotating the stock 90 degrees with every pass through the mill.
When rolling wire or rod, rotate the metal to prevent wings from developing as metal is squished out the sides of the mill slots. If wings do form, immediately file them off.
Although it may seem like a lot to remember, making your own sheet or wire is actually a pretty simple process. For Ballard, the hassle of mastering it is well worth it. Since you’re starting with clean metal, if you make any mistakes along the way, you can simply melt the metal down and try again. “The metal isn’t that delicate,” he says. “If it hasn’t been cast, it isn’t contaminated. If stuff doesn’t come out, re-melt and start over.
“It’s going to be a revolution in your work,” he adds. “Have a good time, and be prepared to be really impressed with what you can do.”