Soft solder is typically thought of when solder or soldering is mentioned, with a typical melting range of 90 to 450 °C (190 to 840 °F). It is commonly used in electronics, plumbing, and assembly of sheet metal parts. Manual soldering uses a soldering iron or soldering gun.Alloys that melt between 180 and 190 °C (360 and 370 °F) are the most commonly used. Soldering performed using alloys with a melting point above 450 °C (840 °F) is called 'hard soldering', 'silver soldering', or brazing.
For certain proportions an alloy becomes eutectic and melts at a single temperature; non-eutectic alloys have markedly different HYPERLINK "http://en.wikipedia.org/wiki/Solidus_(chemistry)" \o "Solidus (chemistry)" solidusand HYPERLINK "http://en.wikipedia.org/wiki/Liquidus" \o "Liquidus" liquidus temperatures, and within that range they exist as a paste of solid particles in a melt of the lower-melting phase. In electrical work, if the joint is disturbed in the pasty state before it has solidified totally, a poor electrical connection may result; use of eutectic solder reduces this problem. The pasty state of a non-eutectic solder can be exploited in plumbing as it allows molding of the solder during cooling, e.g. for ensuring watertight joint of pipes, resulting in a so-called 'wiped joint'.
For electrical and electronics work solder wire is available in a range of thicknesses for hand-soldering, and with cores containing flux. It is also available as a paste or as a preformed foil shaped to match the workpiece, more suitable for mechanized mass-production. Alloys of lead and tin were universally used in the past, and are still available; they are particularly convenient for hand-soldering. Lead-free solder, somewhat less convenient for hand-soldering, is often used to avoid the