Sapphire 179 Solder (Super Versatile) The solder that in combination with our Sapphire No Clean Flux makes everyone an expert! Sapphire 179 solder is 0.6mm diameter solder which flows absolutely brilliantly. It is perfect for brass copper wiring trackwork soldering to nickel silver or steel and it even solders spring steel and to 300 and 400 series stainless steel when used with the right flux. It has a very narrow melt range which makes dry joints a thing of the past. It has a multiple flux core to assist wetting and flow. Because it contains some silver it ts is a little more expensive than standard solders but we make no apology for that as this specially formulated solder is simply the very best available anywhere! Sapphire 179 used by many electronics experts and some of the worlds best professional loco builders simply because it works better!