Raising bowls: brass and enamelled copper

 I’ve been working with wood, fabric and leather for a while now. Though I love working with these materials, I sometimes feel limited in the options I have when making things. As soon as I need hardware for something, I have to buy it. I have dabbled a bit in metalworking in the past, making knives (from blade blanks) and some hardware for guitars, but I always felt very limited. I just lacked the skills to really make something from metal. So I decided to take a class in silversmithing. The form of the class was very free, based on individual guidance while working within a group. I was able to choose what I’d work on myself.

One of the things that have always intrigued me in metalworking is raising vessels. I made the two bowls below as practice pieces. As always, when I start doing something I forget to take pictures. Then, when it actually starts to look pretty, I realize I don´t have any pictures to share with you guys on this blog. So, I´m sorry about the missing pictures of raising the copper bowl. The process was basically the same as the brass bowl.

 This is the copper bowl after sanding. I used 1mm thick copper for this. I decided I´d try enamelling the inside to make it more suitable for putting food in it (it is the ideal size for soy sauce with sushi).

 because the enamel won’t stick to the sides of the bowl by itself, I had to use something to stick it to the sides. My teacher actually had little experience with that kind of thing, so this would be an experiment.

Before I put the enamel on the copper, I had to grind and wash it. I did this with this little mortar and pestle. I washed the enamel three times, each time carefully draining the water. You could put this water in a jar and let the enamel powder in it settle to save it, if you’re really frugal.

After washing the enamel I put it on a paper on top of the enameling oven to dry.

After drying the enamel powder is ready to sprinkle on the bowl, using a fine sieve.

But first I thoroughly cleaned the copper bowl. Step 1: degreasing in the acid bath.

Step 2: a thorough polishing with a glass brush. Wash away any glass from the brush regularly, the stuff hurts if it touches your skin.

So, after brushing on the enamelling glue and sprinkling on the enamel, the bowl was ready for firing. This was a soft enamel, requiring and oven of 725 degrees celcius.

Firing takes a couple of seconds. You know it’s ready when you see the enamel flow. The heat causes the copper to oxidate, creating black stuff that peels off (firescale). This has to be cleaned off before applying another layer of enamel. The enamel glue wasn’t really doing it’s job, leaving spots open on the sides of the bowl.

This is the final result after three layers of enamel. Even though it’s not what I imagined it would be, I’m pretty happy with the result.

A week later I made the bigger brass bowl. Brass is a bit harder to work, and you can’t really enamel it (because it contains nickel).

This time I remembered to take pictures. Step 1: punch the center. Don’t punch too deep, or it will show in the final bowl. Scribe a circle using a compass. This one has a radius of 10cm (4″), and it’s made from 1mm thick copper sheet.

These are most of the tools I used, with the bowl halfway done. I started by using a heavy round-headed hammer (the ball side of a ball-peen is fine), hammering in a snail shell pattern from the outside inwards. Make sure you don’t skip large parts while hammering, but put the indentations closely together. Brass and copper harden from working. After about 60% deformation, it needs to be annealed to make it workable again.

To anneal, heat the brass until glowing a dull red, then quench it in water. 

The sides will be a bit wonky after working. I sanded them flat on some wet-dry sanding paper, using a bit of soap as lubricant. 

And this is the end result after a bit of sanding.