Buying Guide

Types of Soldering and Flux

Flux Types and Features

Flux is a chemical agent used to join and clean metals. It is made from organic or inorganic materials and is available in liquid and paste forms. The best soldering flux for your project depends on many factors and characteristics.

  

Paste 

  • Cleans and fluxes simultaneously
  • Lead-free
  • Removes surface oxidation from pipes
  • Can be used on all materials except aluminum and stainless steel


Tinning Paste 

  • Contains lead-free solder wire in powder form to clean and pre-tin the pipe surface, which allows solder to easily draw into the joint
  • Ideal for use with large diameter copper pipe
  • Little expertise needed for effective use


Hot Weather Formula Paste

  • Ideal for areas with high temperatures


Water Soluble Paste

  • Cleans and fluxes simultaneously
  • Ideal for working with supply lines for drinking water, copper, fire sprinklers and hydronic heating systems
  • Meets plumbing code ASTM B-813 standards for flux used in potable water systems
  • Meets plumbing code requirements for water flushable fluxes


Water Soluble Tinning Paste

  • Contains lead-free solder wire in powder form to clean and pre-tin copper pipe surfaces, which allows solder to easily draw into the joint
  • Won’t turn copper green
  • Meets ASTM B-813 standards and is approved for use by model plumbing code
  • Ideal for use with large diameter copper pipe
  • Little expertise needed for effective use


Liquid

  • Cleans the surface of pipes and prepares them for solder
  • Features a strong cleaning agent which cleans oxidized copper
  • Allows for fast, effective soldering
Shop Flux Types
Description Feature/Benefits
solder Paste Cleans and fluxes simultaneously. Lead-free. Removes surface oxidation from pipes. Can be used on all materials except aluminum and stainless steel.
solder Tinning paste Contains lead-free solder wire in powder form to clean and pre-tin the pipe surface, which allows solder to easily draw into the joint. Ideal for use with large diameter copper pipe. Little expertise needed for effective use.
Hot Weather Formula Paste Hot weather formula paste Ideal for areas with high temperatures.
Forney - Solder Flux Water soluble paste Cleans and fluxes simultaneously. Ideal for working with supply lines for drinking water, copper, fire sprinklers and hydronic heating systems. Meets plumbing code ASTM B-813 standards for flux used in potable water systems. Meets plumbing code requirements for water flushable fluxes.
Water soluble tinning paste Water soluble tinning paste Contains lead-free solder wire in powder form to clean and pre-tin copper pipe surfaces, which allows solder to easily draw into the joint. Won’t turn copper green. Meets ASTM B-813 standards and is approved for use by model plumbing code. Ideal for use with large diameter copper pipe. Little expertise needed for effective use.
Liquid Solder Liquid Cleans the surface of pipes and prepares them for solder. Features a strong cleaning agent which cleans oxidized copper. Allows for fast, effective soldering.
Solder

Solder is a metal alloy made up of different elements. Solder may also be used for a process similar to soldering called brazing, which requires its own special material and higher temperatures than soldering.
 

The U.S. Safe Water Drinking Act prohibits the use of leaded solders on lines carrying drinking water. Lead-free plumbing solders are required for use on pipes carrying drinking water, also known as potable water lines.
 

Leaded solders are available for applications that will not come into contact with potable water, such as sheet metal repair or copper drain lines.


Tip: Read our guide on How to Solder Copper Pipes for detailed instructions through this process.

Brazing

Brazing is another method for joining metal pipe pieces together. In general, soldering takes place at temperatures below 840 F while brazing occurs at higher temperatures. Brazing is used when high joint strength is required. 


Hard solder, which is used for brazing, melts at higher temperatures and is available in various degrees of hardness. 


Brazing requires a different kind of flux and solder. The flux is formulated to withstand the higher temperatures associated with brazing. The filler is a different combination of metals that melt at a higher temperature and are stronger when cooled.

Safety

Safety should always be one of your foremost concerns when soldering or brazing. Always use fire retardant protection like a heat cloth or flame protection blanket when working around combustible elements like wood, drywall and insulation.


  • Keep a fire extinguisher nearby at all times.
  • Wear safety glasses, a helmet and protective gloves.
  • Wash off excess flux after soldering to prevent corrosion.
  • Do not use flux on electrical parts.
  • Use adequate ventilation when fluxing and soldering, particularly in close quarters.
  • Always refer to a professional in your area for codes or additional safety tips.
Helpful Tools

When soldering, there are several tools such as tube cutters, flame protectors and emery cloths that can help make your work look professional and keep you safe when working. 


  • Tube cutters: Help ensure smooth, even cuts when working with plastic tubing, minimizing the amount of time you’ll have to spend sanding, and ensuring a better solder. 
  • Flame protector: If you’re heating a joint near combustible material, use a flame protector or heat shield to protect the heat-sensitive material from damage.
  • Deburring tool: Makes it much easier to remove burrs and rough edges from pipes once they’ve been cut.
  • Emery cloth: Use strips of emery cloth to clean and prepare copper pipes for the application of flux and solder.