Solder is a material that is used to bond objects, such as pipes or wires, together permanently. The primary application for soldering in the plumbing industry is leak-free connections. In the electronics industry, soldering is used to fuse wires for circuit components.
For soldering plumbing, heat is applied by a torch to the joint between the copper pipe and fitting. Once heated, solder is placed at the joint and will melt and flow to seal it. This joining provides a bond between the pipe and fitting.
Solder is a metal or metallic alloy that historically consisted of lead and tin in various proportions. Today, lead-free solder is available to comply with the Safe Water Drinking Act, which restricts the amount of lead used in portable water systems.
Let's take a look at the three different types of soldering.
Types of solder
1. Lead-Based Solder
Lead solder, made of lead and tin, is used for most electronic manufacturing applications to form a strong bond between the joints of other metals, such as copper and aluminum. Lead-based solder is not used with pipes that handle water.
2. Lead-Free Solder
Lead-free solder generally has a higher melting point than conventional solder.
● Tin-antimony solder: Contains 95% tin and 5% antimony. This type of solder is lead-free and therefore safe for water supply lines. Designed for use in plumbing applications where frequent extreme temperature changes and vibrations occur (refrigeration, cooling equipment, and heat ducts, it is also used to solder electronics. We recommend using acid core 95/5 on duct working and rosin core 95/5 for electrical. The melting range is 450°F to 464°F and has an unlimited shelf life.
● Copper-tin solder: Contains 97% tin and 3% copper. Lead-free and safe for water supply lines, this solder type is designed for sweating copper and brass plumbing joints. The melting range is 440°F to 572°F, and it has an unlimited shelf life.
● Silver-bearing solder: Contains silver, copper, bismuth, and tin. Lead-free and safe for water supply lines, this solder is ideal for low-lead brass applications. It has a wide melting range (420°F to 460°F), enabling more time for soldering joints.
Types of Flux
Flux is formulated to clear the pipe and fitting of any surface oxidation. All Oatey fluxes are lead-free, are NSF, and have a shelf life of two years from the date of manufacture.
There are four types of flux you can choose from based on your application:
● Petroleum-based Flux (or Petrolatum Flux): Flushing is required and designed to provide superior wetting properties for better solder flow. This flux is compatible with all common plumbing solder alloys, such as copper, copper-coated metals, brass, zinc, galvanized iron, lead, and tin.
● Water-soluble Flux: Water flushable and compatible with all common plumbing solder alloys, it is less corrosive since it self-cleans the pipe's interior as water flows through the lines. This flux has a narrower temperature range when heated, but works with all solders.
● Hot Weather Flux: Specially formulated for hot-weather climates, this flux will not separate in temperatures up to 135°F.
● Tinning Flux: Available in both water-soluble and petroleum-based formulas, this flux is enhanced with tinning-powder particles to pre-tin piping and improve the flow of solder, while also enabling even heating of a fitting. The latter is necessary when soldering low-lead brass or large-diameter piping systems. It is compatible with all common plumbing solder alloys.
Additional tips
● You may need some supplies along with your solder for certain applications. Most solder kits include a wire-fitting brush, a sand cloth, and, depending on the type of solder, a container of soldering flux and a flux brush.
● If you are soldering near something flammable, consider using Oatey Flame Protector, so the surface does not burn or catch fire. Position the flame protector between the joint and the surface to prevent damage.
● When using solder on your next project, we recommend you refer to the manufacturer's instructions for product-specific application and safety guidelines.