Working with steel wire is different than working with copper or silver wire; it is much stiffer and more difficult to cut. But, it provides a unique look that you cannot get with other kinds of wire.
Mild-steel wire is available at most hardware stores in a range of gauges, so if you create your own design, consider how you can utilize the wire thicknesses to create a variety of line weights and emphasis in your final piece. The wire comes with a black, oily coating on it that prevents rust (it’s sometimes wrapped in oiled paper), but that oil also prevents the flow of solder, so it’s important to remove it before you continue.
Use dedicated wire cutters, files, and sandpaper for working with steel. Steel contamination on non-ferrous metals may eventually migrate to your pickle pot, causing other metals to copper plate. Don’t use your high-quality pliers with steel, either. Be sure to use heavy-duty cutters.
Use black brazing flux
Steel doesn’t transfer heat like silver or copper. For a silver or copper piece, you must heat the entire piece in order for one join to become hot enough to allow solder to flow. Steel, on the other hand, will spot heat just in the area where the torch is aimed, getting hotter and glowing brighter than any non-ferrous metal will. I recommend using a long-lasting black brazing flux, such as Handy Flux Type B-1 or StaySilv Black Flux. This flux remains effective up to 1700°F (926.7°C), 200° hotter than regular white paste flux. White paste flux will work, but the high heat tolerance of the black flux will make this project much easier.
Use this product only with effective ventilation, and avoid contact with the paste and fumes.