Solder

Common types are leaded (Sn63Pb37), lead-free (typically tin-silver-copper alloys), and specialty solders for high-temperature or electronics work; choose leaded for easier wetting and lower melting point when allowed, lead-free for regulatory or health reasons, and select flux core or separate flux depending on joint cleanliness and application

For electronics, thin wire (0.020–0.040 in / 0.5–1.0 mm) with a rosin-based flux core is common; for general-purpose or larger joints use 0.06–0.12 in (1.5–3.0 mm) or larger and stronger fluxes; plumbing and HVAC require plumbing-grade solder and flux or brazing rods rated for higher temperatures

Flux removes oxides and improves solder flow; rosin-based (R, RMA, RA) fluxes are typical for electronics, with R (rosin) being least active and RA being most active; water-soluble fluxes clean more thoroughly but require rinsing, while no-clean fluxes leave minimal residue

Work in a well-ventilated area or use fume extraction, wash hands after handling leaded solder, avoid inhaling flux fumes, use eye protection and heat-resistant tools, and follow local regulations for disposal of waste solder and flux residues

Store solder and flux in a cool, dry place away from direct sunlight; unopened solder wire lasts years, while flux and paste have manufacturer-specified shelf lives—typically months to a couple of years—and may require refrigeration for longer life per product instructions

Expect to also need a temperature-controlled soldering iron or station, soldering tip cleaner and spare tips, flux (paste or liquid), desoldering braid or pump, and basic hand tools like tweezers and cutters; entry-level setups commonly fall under modest budgets while professional stations cost more

A good solder joint is shiny (for rosin flux), smooth, fully wets both surfaces without gaps or excess solder, and is mechanically sound; dull, grainy, or cracked joints, or joints with excess flux residue or bridging, should be reheated, cleaned, and redone