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So in this video, we're going to look at annelling and

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basically the annelling 

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process is where we are

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heating the metal up to soften it,

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so it will take a deeper pattern

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and it'll be easier to work.

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We're going to use 

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the gas torch to heat the 

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little piece of copper up 

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to a cherry red color. 

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And that's about 650 degrees.

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And what the heating up

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does is to take the stresses

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and strains out of the metal. 

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And if you imagine 

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the metal had a grain 

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and as you hammered 

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the metal and bent it,

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the grain gets all mixed up

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and the metal doesn't 

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want to slide within itself.

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So by heating it up, 

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you bring those that grain into

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a more uniform pattern 

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and it slides more easily within itself.

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The process is quite simple. 

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We're going to 

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use a little bit of a piece of metal

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that we put through the roller, 

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and if we wanted to 

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do any more texturing to this 

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because it's been through the roller, 

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it's become quite work hardened. 

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So any more work 

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would be very hard to do, and

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we probably wouldn't get a very, very 

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good finish to it. 

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So we're going to annele it 

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and we use the gas torches,

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as I've said before. 

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And what we're going to do 

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is we're going to lean our piece of metal

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against a little heat block.

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If we lay it down on the block, then the

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the brick absorbs the lot of the heat

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and it takes a long time to heat up.

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So if we lean it up against a brick,

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then we can get the heat 

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all the way around 

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and it'll heat up a lot quicker.

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We're going to see 

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the different colors as the

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metal heats up and some of 

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the colors we can, we can retain

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they're only microns thick. 

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But they are sort of interesting

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purples and blues and things. 

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But what we're aiming for 

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is a nice cherry red colour. 

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And this will take all the stresses

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and strains out of the metal. 

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So now we've switched the pump on

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because our torches work on gas and air,

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and the red pipe is the gas

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and it's just normal gas, 

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just like it is in your home

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for the cooker or heating. 

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But the black pipe 

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we use to pump air through.

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You can hear the pump 

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whirring in the background. 

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The torches have a little pilot light,

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which are lit all the time, 

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and by just turning the little tap on,

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the torch will light automatically.

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And what the pumped air does is

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makes the flame a lot hotter.

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So without the air, 

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we can turn it off 

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with this little button here 

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we just get this sort of hot,

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well, bushy flame, 

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which isn't really hot enough to heat

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a little piece of copper to a cherry red,

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but it's useful for just 

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heating things up gradually. 

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And as I take my finger off 

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and allow more air 

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to mix with the flame, 

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then it becomes a lot 

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stronger and hotter. 

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And we don't need anything 

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dramatic at the minute, but a nice flame,

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and we're going to use it 

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just to, 

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we're going to paint

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the flame onto the metal,

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and it's a good habit to get into,

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that you're going to

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continually move 

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the flame, especially with silver

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if you hold it in one position.

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You get hot spots and 

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you're liable to melt 

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the metal and things. 

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So if you get into a good habit of

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keeping the flame moving, 

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you can heat the metal up 

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to a nice constant temperature all over.

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And we can see all the colors appear

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and now we're aiming

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for a cherry red color, and this is

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the colour were aiming for, 

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and this is about 650 degrees.

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And if we retain that, 

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then if it's a thick piece of metal,

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then the heat goes 

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right into the middle of the metal. 

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But once we've had 

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about five seconds of that, 

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then we can take the heat off

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and switch the torch off.

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Now remember, this is 

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everything around here is very hot. 

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So we're going to use tweezers 

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to pick up the metal

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nice and carefully 

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and then straight into the sink.

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And that cools down 

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because it's a really good conductor 

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it cools down very quickly.

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But now we can see this is so bendy

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and it's almost like 

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a piece of chewing gum 

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because we've taken the stresses 

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and strains out. 

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But if we continue to bend it,

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then it would become work 

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hardened again, and 

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we would have to annele it 

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again. 

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If you were raising a bowl 

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or making a complicated shape,

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then you may have to do annelling

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process, maybe up to 20 or 30 times.

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What happens when we heat the metal up,

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especially copper 

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and silver, they oxidize.

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It's a reaction between 

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the oxygen in the flame 

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and the atmosphere. 

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Reacting with the copper 

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and silver has a small content of copper. 

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So the copper oxidizes and what we do

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to get rid of all these.

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It's not so bad this one, 

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but sometimes it's 

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got a black coating on the surface.

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And if we're doing further work to it, 

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it might inhibit the further processes.

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But we have just here.

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We've got a an acid bath

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and this is a it's a 5% solution

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of sulfuric acid and water. 

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Inside there's a little basket

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and we use our copper tungs

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and we can see the basket inside there

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and what the sulfuric acid

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does is it's on the surface of the metal

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and it cleans away the oxidization

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It's only a 5% solution of sulfuric acid.

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So if you've got 

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paper cuts on your finger, 

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you may feel it, 

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but it won't eat holes in your fingers.

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But because it's in a 

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nice, safe container 

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and the container has 

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got a little tank of

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warm water around it, 

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then it's easy to pick up with tweezers

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and put back in the sink 

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and give it a good rinse 

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to get rid of any acid solution on it.

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And then it's ready for the next process.