By Richard Asmus – Updated March 24, 2022

Welding

Welding is a process that melts the base metals and a filler material to create a joint that is often as strong as the parent material. The heat source can be a gas torch or an electric arc, producing temperatures well above 5,000 °F, depending on the metals involved.

Soldering

Soldering, in contrast, heats the base metals only to a point where a lower‑temperature solder alloy melts. The base metals remain solid, and the solder fills the joint by capillary action, hardening upon cooling.

Soft Soldering

Soft soldering, used primarily in electrical work and copper plumbing, employs alloys that melt at up to 475 °F (240 °C). An electric soldering iron or a low‑heat torch is typically sufficient.

Hard Soldering (Silver Soldering)

Hard soldering, or silver soldering, uses alloys with melting points up to 840 °F (450 °C), allowing bonding of a broader range of metals. A gas torch is usually required.

When to Choose Which Technique

• Welding – Best for structural applications that demand high strength and durability.
• Soldering – Ideal for electrical connections, plumbing, and situations where the base metals should remain unchanged.