Solid wire electrode

Solid wire is simply bare welding wire fed directly into the melt. There's no filler or powder in it, just the pure metal. That gives you a clean, homogeneous seam if the settings are right.

Make sure the wire is clean and dry – rust or grease will immediately give you pores in the seam. The wire feed has to run smoothly, otherwise the arc flickers and the seam becomes irregular. You regulate the heat via travel speed and wire thickness – you need to get a feel for the material.

If the seam looks bad, it's usually due to wrong wire speed or too much distance from the melt. Keep the torch steady and even, then it'll work out.