Soldering No Lead Brass – An Industry FYI

Soldering No Lead Brass

Many No Lead or lead-free alloys use special chemicals in their composition, making heat diffusion more difficult.  As a result, it is more challenging for solder to adhere to No Lead silicon brass than to traditional leaded brass.  For No Lead brass, a different procedure is required to make common plumbing solder joints.

Traditional Standard Brass:

In the past, the presence of lead in a fitting allowed a torch’s heat to transfer thermally within a fitting, allowing the solder to flow quicker and more uniformly. Today, contractors and tradesmen deal with many No Lead alloys and specifically silicon alloys that do not act the same way.

Download and Share Sioux Chief’s Free Technical Bulletin on Soldering No Lead Brass


If proper procedures are not followed, joints may be compromised resulting in leaks and future issues. Reference Sioux Chief’s Tech Bulletin on soldering No Lead brass. (TB 8-15-13) or Sioux Chief’s Tech Bulletin on the material differences between commonly available No Lead alloys.

Procedural Tip: Applying Heat

The most critical factor in making a proper joint is to make sure to bring the temperature of the fitting up slowly and evenly. Traditionally, fittings with lead content allowed for heat to be applied in one location while still providing a strong joint. This ‘short cut’ method will no longer provide an adequate joint.

Applying heat quickly and unevenly will cause the flux to burn out on the hot side (torch side) before the opposite side is hot enough for solder to melt. Therefore, apply heat by constantly moving the torch tip around the joint, never stopping in one spot.

Tradesmen should follow all the normal soldering techniques (applying heat evenly and uniformly) that would be used on any other solder joint, but with extra caution on the constant and uniform application of heat throughout the entire fitting in order to achieve the necessary capillary action.  Contact the solder or flux provider for specific No Lead products and heating procedures.

Sioux Chief No Lead Brass:

Sioux Chief’s No Lead alloys, by nature of their alloying elements, achieve higher dezincification resistance and stress corrosion cracking resistance, but must be treated with greater care when soldering.

Download and Share Sioux Chief’s Free Technical Bulletin on Soldering No Lead Brass