Tips to Achieve a professional finish to your mirrors or windows!
I will be brief here as there are many books fully describing leading techniques.
Stained Glass mirrors really catch the eye, especially if you have chosen strong colours-although plain mirror and lead look great if you have the right design. Opaque and iridized glass work well. If you have chosen transparent glass for parts of your mirror, place white paper behind those parts before adding backing. And just the right frame will really set your mirror off.
1. Treat mirrored glass with respect, being very careful that you don't scratch the silver off the back of it. Score on the front mirror surface, cut on a towel and shake off any slivers of glass.
2. I prefer to surround mirror glass only with lead, due to the acid in flux, black spotting can sometimes appear on the edge of the mirror. If you do want to use foil around the edge there are different brands of flux on the market that you could try or apply nail varnish or a recommended paint from a glass supplier around the edges of the mirror and use non-toxic flux, tallow candle or whatever your leadlight supplier advises you to use. Tallow candle is completely safe and will not harm mirror backing. Use tallow candle on any lead joints adjacent to your mirror, giving them a good scrub first with a wire brush, this way your solder will take easily and neatly. You can use your normal flux for the rest of your mirror.
3. How to get lovely black solder joints:- To make black solder joints, putty, trim, then give your mirror a good scrub (paying attention to the joints) with a bristle brush and a small amount of whiting. (sprinkle whiting on like you are sprinkling icing sugar over a sponge cake! Otherwise you will end up in a cloud of whiting.) Apply stoveblack polish sparingly with toothbrush and buff lightly. If joints become silver again, scrub again with a hard bristle brush. Do this as soon as you have finished soldering, as your joints will begin to oxidise and this will make it harder to achieve a nice shiny black joint.
4. Use this technique for soldering and polishing window panels as well, except you only need to use your usual flux.