If there is a small hole in a ‘tin’ kettle, it may be mended by taking two thin metal discs, and placing one on either side of the hole. The two may then be clamped together by means of a small nut and bolt.
If this is not satisfactory, or in the case of a heavy iron kettle, soldering will be resorted to. A soldering iron is the first necessity, a stick of solder and some flux. There are several good proprietary brands of the latter. See that the kettle is thoroughly dry inside and out ; then fill with water and carefully examine for wet places, representing the leaks. Next, empty the water, and support the kettle so that the leak may be conveniently placed. With an old chisel, scrape all around the damaged place until it is absolutely bright. Where the edge of the chisel will not penetrate use the point of an awl, alternate this action with ample rubbing with glass paper. When the edge of the leak and a small space all round is bright, put the soldering iron in the clear part of a hot fire and leave until nearly red. While waiting, dab all round the hole with flux, and when the iron is ready, plunge the tip in the same material. Quickly bring the stick of solder to the hole, melt some off with the point of the iron, and run it over the bright parts. If the hole is a fair size, try a sort of bridging action. If the solder refuses to hold, you have probably not made the surface sufficiently bright, and the work must be done over again.
For large holes, the best plan is to clean all round the edge as before, and cut a small piece of tinned iron, just big enough to make a suitable patch. First lay a coat of solder all round the hole, then cover the underside of the patch with the same material, put it in position, then sweat the two together by running the hot iron over the part that has been treated.