Introduction: Foldformed Copper Bracelet With Red Heat Patina
The main purpose of this Instructable is to show you how to get vibrant red colors on copper sheet using a simple heat patina. This can be done with one household ingredient, plus a torch (and necessary safety equipment for working with a torch and hot metal). An ordinary propane blowtorch will work for small pieces and thin sheet, but hotter torches (acetylene or oxyacetylene) will make it much easier to get vivid, solid reds, especially if you're using thicker sheet or making larger items.
Please do not try this if you are not already familiar with torches and working with very hot metal. Proceed at your own risk.
It's more interesting to have a finished piece at the end, not just a pretty piece of copper scrap, so I'll also show you how to make a simple foldformed cuff bracelet out of thin copper roof flashing. If you just want to know how to make the copper red, you can skip to that step. I'll show you how to do this with minimal tools.
What you need for the red heat patina:
- Thin copper sheet: I use .0216" (approx .5mm) copper, also known as 16-ounce. Commonly used for roof flashing. Thicker than .032" (.8mm) will get harder to work without more tools, and a lot harder to get the red color unless you have a hotter torch.
- Borax (from the grocery store or hardware store - normally used as a laundry additive)
- Cheap natural bristle brush - get a really cheap one (or three) from the hardware store. I use 1 inch wide.
- Glass jar and water
- Torch (propane blowtorch is okay, but use acetylene or oxyacetylene if you have access to them)
- Firebrick or other torch-safe surface for heating your work on: concrete, stone, and normal bricks are NOT safe
- Safety glasses
- Good ventilation
In addition, to make the bracelet, you'll need:
- Metal shears or tinsnips (or a bench shear)
- Fine metal file
- Hammer (small is best)
- Anvil or something to use as an anvil (vises have anvil heads usually, or you can clamp a big hammer in a vise, or use a heavy piece of steel, or a chunk of railroad)
- Large metal pipe or something similar to shape the bracelet around, unless your anvil already has a nice round part to make this easy
- Pencil, paper, tape
- Work gloves are good
- Putty knife
- Cross-peen hammer for textured version of the bracelet
- Small rawhide or rubber-faced hammer for smoothing down the edges
- Coarse metal file, or belt or drum sander, or rotary tool with sanding drum, to make edge cleanup faster
- Polishing wheel (for bench grinder or mounted on a rotary tool)
- Cupronil liquid flux and spray bottle for more even coating and color
- Acetylene or oxyacetylene torch, to make everything quicker, and get better reds
- Acrylic spray, or lacquer, or other skin-safe clearcoat
Step 1: Sizing the Bracelet
To make a bracelet that will fit you, cut a strip of paper and wrap it around your wrist. Tape it to itself, and mark where the end comes to. Then put another mark on the overlapped part for the other side of the opening, far enough that you can get the bracelet off your wrist. You'll probably need at least 1-1/4" (3cm or so), less if you have very small wrists. You can turn the band to the side of your wrist as shown here to get an idea how much space you need.
Break or cut the tape and unwrap the strip, to see how long you need to cut your bracelet blank. Mine came out to 5-3/8" (13.6cm), which is on the small side for men, and medium to large for women, but everyone's wrists are different, and the range of sizes across all people is very, very wide. Also, if you like to wear your bracelets loose, you will want to cut the blank a bit longer.
Step 2: Cutting the Blank
Cut a strip off your copper the width of your bracelet. The ones shown in the photos are right around 1" (2.5cm). (I would not do less than about 3/4" or 2cm, and if you're going to use a propane torch, I would recommend no more than about 1-1/4" or 3cm, because the larger mass of metal will heat slower.) Then cut the strip to the length you measured on your wrist.
Roof flashing copper is easy to cut with metal shears, though if you have a bench shear, all the better. If you find the copper getting folded or mangled in your shears, try tightening the shears if you can. You want to be careful not to cut too raggedly; pointy bits from ragged cuts can be extremely sharp, and will take you a long time to clean up.
Trim the corners of the strip reasonably round with your shears. Then file the ends to a nice smooth curvature, and file away all the cutting burs. If you don't have a metal file you can do this with a sanding block, but it's tedious. A coarse file can make this quicker, and a belt sander or drum sander with fine sandpaper can make it much quicker; if you use power tools, wear leather gloves both to protect you from the sander and because you may make the copper heat up a lot and burn yourself.
Step 3: Foldforming
This section is shown in the video above. I've included a few timestamps below for navigation.
This is the simplest operation within the world of techniques known as 'foldforming'. In our studio, we call this creaseforming. We are just folding the blank in half the long way, then hammering down a crease just enough to compress it and form a ridge. This will give the bracelet strength, as well as visual interest.
With 16-ounce copper, you can fold it by hand, either by clamping it in a vise and pushing it over to the side, or just with your hands if you have reasonably strong hands. (I hope you cleaned the edges up well in the last step - you don't want to cut your fingers!)
However, since you have a torch handy, you can make the fold a lot easier by annealing the metal first. This means heating it up till it glows, and letting it cool. After annealing, the copper will be much softer.
00:00 To anneal the blank, put it on your firebrick, put on your safety glasses and have your pliers handy. You should do this in good ventilation, but it's also best to do it in low light. In full sunlight it's very hard to see a gentle red glow in your copper.
Light the torch and start heating the blank. Note that the hottest point in the torch flame is where the conical inner flame comes to a point. (If you're using oxyacetylene you want a reducing flame, and it will heat the small piece of metal very quickly, so you won't need too much finesse.)
Preheat the blank by running back and forth over it until you start seeing a black chasing shadow following the torch across the surface. Then slow down and concentrate on one end, and move slowly along the band, looking to see if it is starting to glow. If it isn't quite glowing yet, slow down and stay on the spot until it does. For an anneal, you don't need to heat it to an orange glow - even a dim red will make it much easier to fold.
01:41 When you have gotten all parts of the bracelet to glow a bit (not necessarily all at once), let it cool. It will stop glowing quickly, but it will still be VERY hot for a while - like the metal inside an oven. To cool it faster, you can use your pliers to move it to another part of the firebrick, or put it on your anvil, where the mass of metal will steal heat from the bracelet more quickly. It will be cool enough to touch after a few minutes. If you want, you can quench the bracelet in a water bucket, and it'll cool off almost instantly. Unlike steel, quenching hot copper doesn't make it harden. If you do quench it, dry it off before putting it on your anvil; in general it's best not to get too much water on good iron and steel tools.
02:05 Once you've annealed it and let it cool completely, you can fold the blank in half the long way quite easily by hand. It will feel almost as soft as leather to begin with, but as you handle it it will start work hardening. 02:56 Once it's folded in half, take it to the anvil, or clamp a big hammer in a vise, or whatever you're using, and start hammering down the crease. Don't just barely crease it - hit it a few more times everywhere along the edge to thin and splay out the edge a bit. This will harden it, make a prettier edge, and start curling the whole bracelet a bit. Careful hammering can even up the edge into a nice, continuous curve. Precise hammering for jewelry work is a skill that takes time to master, but even if your edge is uneven it will make a nice bracelet.
03:46 If you have a cross-peen hammer, you can go over the edge again with the edge of the cross-peen, to make an interesting serrated look along the edge. You can do this on one side or both. If you've hammered the edge thin enough to make it sharp anywhere, carefully file that down before going on.
04:38 Next, you will need to anneal the bracelet again. Take it back to your firebrick, don't forget your safety equipment, and heat it up again till it glows. Copper conducts heat well enough that you probably only need to heat from one side to get the piece fully annealed, but if you want you can turn it over (with your pliers!) and heat the other side too. Let it cool completely again (or quench it).
06:45 The final step in foldforming is to unfold the piece again. Once it's completely cool, you can start opening it up. If you have strong nails, your thumbnail should be enough to get it started. If not, a putty knife or a butter knife or a thin piece of some metal harder than copper will help. If using a putty knife or other tool, be careful and don't push the knife toward your fingers or hand. Putty knives can be surprisingly dangerous. Once you've started to open the fold, you should be able to do the rest by hand. You don't need to get it all the way flat just yet.
Now you're ready to shape the bracelet!
Step 4: Shaping the Bracelet
With copper this thin, shaping the bracelet is very easy.
If you have an anvil with a horn, or a bracelet mandrel, you can use those. If not, use a rigid pipe, ideally clamped in a vise. I show both versions in the video above.
Before you start, check the ends of the bracelet by running your finger over them every direction. If they're sharp or scratchy, carefully file them with a fine file till they're smooth enough, since they will be drawn over your wrist every time you put the bracelet on or take it off. If you have a polishing wheel on a bench grinder or on a flexshaft or Dremel tool, that is a quicker and easier way to soften the edge.
To form the bracelet, start at one end and press it against your pipe or other round form. If you find pushing down on the hammered edge uncomfortable, you can use a glove. If the bracelet is getting too stiff to work, you can anneal it again the way you did in the previous step.
Be careful not to fold or kink the bracelet, but just give it a gentle curve around till it's a nice C shape. If you want to clean up wiggly edges, you can use a soft hammer gently on the edges against your curved anvil.
Step 5: Red Heat Patina
Finally we're at the best part: turning it red.
[Timestamps refer to the video above. Another version of this process, using a liquid flux and an oxyacetylene torch for more vivid reds, is shown in the video linked the final step below, starting at 06:23]
You may have noticed that you get some red colors on parts of the bracelet when you anneal it - especially the parts sitting against your firebrick, somewhat protected from the air as it cools. In the video, the bracelets are already pretty red colors before I start, just from the annealing, and sometimes I just leave them that way. This process is just a way of getting that red color more consistently, and protecting it by forming a thin layer of a sort of glass over the surface. It will work on freshly cleaned, bright copper as well.
0:00 Put a small amount of borax in your jar, and add water to make a very thin slurry. Maybe 2 Tbsp of water to 1 Tbsp borax. Borax is not very bad, but you don't want it in your eyes, so you should wear safety glasses to protect against splashes. Stir this up with the brush till a bunch of the borax dissolves in the water. Not all of it will, probably. Don't worry about it. (If you want a more even coat next time, you could grind the borax in a mortar first.) As you use it, keep stirring it up, as it will keep falling out of solution.
00:35 Put the bracelet on the firebrick again. Again, you'll want to work in less than full light to see the glowing metal, and again, you need good ventilation.
You're wearing your safety glasses, right?
Brush some of the borax solution on your bracelet. It won't cover perfectly. You can leave it this way and get a more spotty patina, which will still probably look great, or you can heat the bracelet a little, till the water just evaporates, then brush more on, continuing till you have good coverage with the white residue. If it's too hot, your brush may stick and burn a bit. This is why you do NOT want to use a brush with synthetic bristles, which would melt and make a mess. Once you have it reasonably well covered, set aside the borax and the brush and start heating up the bracelet for real.
00:55 Just like when annealing earlier, you are going to heat the bracelet till it glows. (If you skipped to this step to learn how to get the red color, there's a more extensive discussion of heating the metal back in step 3.) This time, though, you will be happier with the result if you can get it hot quickly, and you want to heat it till it gets to at least a dark orange color, not just a barely glowing red. A quick preheat is still good, but when you start your anneal, heat from one end, using the inner cone tip as the hottest part of the flame, and heat all the way till the glow is a good orange. If you are using an acetylene or oxyacetylene torch, this will be nice and quick. Propane will take longer, and you may need to try a few times to learn to do this reasonably quickly. If it goes beyond orange toward bright orange or yellow, be careful, because it won't be far from melting, and this will be difficult to control on such thin metal. You don't need to get it that hot.
03:50 Once it's all got to orange (not all at once - thin metal will cool very fast, so it would be hard to get an even heat color all over), back off and let it cool slowly in the air. If you had a lot of borax dripped on the firebrick, you might want to pick up the bracelet with the pliers and move it to a different spot on the firebrick or to the anvil to cool, so that you don't get bits of borax fusing to the edge and making it rough.
As it cools, you'll see it go to black first, then start developing its red and orange colors. It will still take a few minutes to cool to where you can touch it. 06:22 When it's cool, take a look. Try it on!
If you don't like the coverage or the color you got, guess what? You can do it again. In fact, I reheated once or twice on the bracelets in the video. If it gives you reddish brown colors, but they fade a bit to less interesting browns after it cools, you need to try to get it up to temperature faster. Add more borax, go for more coverage if you like, and reheat. If you keep getting similar results on a given piece, you can try cleaning it off by pickling it in Sparex and starting over, or use a heavy steel wire brush wheel to clean it down to bright copper before starting over.
Once you've got a color you like, let it sit out for a few hours or overnight to make sure the color is staying. Then I recommend using a spray of acrylic or lacquer to preserve it. Your skin oils will change the color of the bracelet over time, usually darkening it, but this would happen much, much faster if it's not sealed.
07:44 Now you can show it off to your friends!
Step 6: Optional Alternate Method for Red Copper: Liquid Flux
Borax is the old school way to do this, and it works great, and can give you interesting results you won't get other ways. But if you want more even, solid reds, the easiest way is to use a liquid flux* such as Cupronil, and spray it on.
The above video is redundant, showing the whole foldforming process through again, showing how much quicker it is to use an oxyacetylene torch. For just the coloring step using Cupronil, start at 06:23.
(If you want the effect of brushstrokes, you can also brush it onto slightly hot metal, but I use it as a spray.) I generally spritz it all over, then heat till the water evaporates just like with the borax, then spray carefully, alternating gentle heat from the torch in one hand with light mists from the atomizer in the other hand, to get a nice, even, solid icing of white. Then I hit it with the real heat, heat it to red-orange or medium orange, and let it cool as usual.
Note that the use of liquid flux with this method makes it easier to get even coloring, but it is primarily the quick heating from oxyacetylene that gives the intensity of red in the resulting bracelet in this video.
*A flux is a compound used by jewelers which coats and melts onto the surface of a metal while you're heating it up for soldering. The flux coats the surface and keeps air off it, so that the surface does not oxidize at high temperature, which would hurt the solder adhesion. Borax is a common flux, but there are more modern ones, in powder, paste, and liquid form. (There are even 'self-pickling' fluxes now, which are great for soldering, but they will not work for turning copper red.)
Cupronil is a modern liquid flux, available from jewelers' supply shops. It's not cheap, but it'll last you a while, and it is worth trying if you are learning to solder as well.
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