... is that it's possible for them to boil dry. As I mentioned previously, when I was little my mum taught be how to listen for the water boiling, and stressed the importance of not letting the kettle boil dry. I never knew quite why a kettle shouldn't be allowed to boil dry, but I knew it was important. Ian's mum evidently had more modern equipment in her kitchen.
Last Monday morning, after an internet free weekend (i.e. the service was down) that meant Ian was behind with work, he got up early, put the kettle on and started work... and got engrossed in work. Some time later he was startled by a crash from the kitchen, so rushed through to find this:
Once we'd stopped swearing, I assessed the damage. Although it's not obvious in that picture, the kettle had changed colour, so it looked as though all the copper had come off. This is ridiculous, as it's made of copper, with just a thin lining of tin. What had actually happened was that the heat caused a thin film of copper oxide to form, changing the apparent colour of the metal. It shouldn't be too difficult to remove this layer. Of more concern was the absent spout. Well, not so much absent as detached. Looking at the place where the spout used to be, it became obvious what had happened.
The spout had been soldered onto the body of the kettle, and without water to absorb the heat, the kettle just got hotter and hotter until the solder melted and the spout fell off. Now I know why you should never let a kettle boil dry.
Soldering is a job I reckon I could tackle. I did quite a bit of playing around with electronics as a teenager, and as it happens, Dad recently bought me a new soldering iron. But first, what about the solder? I spent some time looking up different types of food grade solder. In fact, I spent the best part of a morning, as was starting to wonder whether I might end up spending as much on solder as I had on the kettle, before I thought to check the tube of solder I had in the cupboard.
That's almost entirely tin, with a tiny bit of copper. Entirely safe to use on my kettle, then. Jolly good.
My first attempts at mending the kettle were a complete failure. Quite apart from the challenges of supporting the body of the kettle whilst holding the spout (liable to get hot) at the same time as soldering iron and solder, I found I just couldn't get the thing hot enough to melt the solder. Hmph. Was my new soldering iron duff? Or was it just not designed for this sort of work?
Chatting with my neighbour Gill a few days later, she (who turns out to have more expertise in this area than I do) confirmed my suspicion that a soldering iron will always struggle to heat a large copper object, because copper is an excellent conductor and whisks the heat away from where you need it. Gill had more to offer than good advice, though, she also lent me her metalworking blowtorch. Thank you!
Even with the right tools, this was still a difficult job. I thought I'd start by tacking the spout on with a little dab of solder, then working around the seam. However, what with copper spreading the heat around as it does, the spout kept falling off again. The only way to do it was all in one go. This meant getting a line of solder all molten at once then fitting the spout in place and holding until it was set (I ended up using kitchen tongs to hold the spout).
That wasn't the end of it because of course it leaked. I had to keep filling the kettle, locating leaks, drying the kettle (steam not helpful when soldering) then applying more solder to that spot, being careful not to heat the kettle so much that the spout came off again. Eventually, though, I had a non leaking kettle.
It's not the prettiest of joins, and the spout isn't quite as vertical as it once was, but we can now use the pretty copper kettle again. I suspect the solder splashes will polish off in time, as tin is much softer than copper, but even if they don't, they just add character, don't they?
Edit: This happened again, while I was away. Evidently my husband cannot be trusted in charge of an old-fashioned kettle. I couldn't face mending it again, knowing that it would probably fail again, so we bought a cheap modern kettle. It's still a stove-top kettle, but it has a whistle. In fact, it has a horrible whistle, so there's a strong incentive to make it shut up. This happened in the summer and I still (late Oct) haven't decided what to do with the spoutless copper kettle.