Wire wool (also known as steel wool) is a common and essential consumable in plumbing, 
primarily used for cleaning and preparing metal surfaces, particularly copper pipes and fittings, before soldering. This preparation is critical for ensuring a strong, watertight, and lasting joint. 
Primary Uses
Surface Preparation for Soldering: Before soldering copper pipes and fittings, plumbers use medium-grade wire wool to remove oxidation, dirt, grease, and any contamination from the surfaces. Cleaning the bare metal ensures proper solder adhesion and joint integrity.
Removing Flux Residues: After the soldering process is complete, wire wool can be used to safely and effectively clean away residual flux from the joint.
Polishing Metal Surfaces: It is effective for bringing a bright shine to various metal surfaces, including aluminium and brass.
Tool Maintenance: Plumbers also use wire wool to remove surface rust and stubborn dirt from their unpainted hand tools, helping to maintain their equipment.