Among the following, which metal is NOT usually preferred as flux for soldering applications?

• Among the all given options except lead, all metals are usually preferred as a flux for soldering applications.
• Soldering is the process by which metallic materials are joined with the help of another liquified metal (solder).
• All metal rust to some extent, when exposed to the atmosphere because of oxidation. The layer of the rust must be removed before soldering. For this, a chemical compound applied to the joint is called flux.

Different types of fluxes are given below

Inorganic fluxes:

Hydrochloric acid: Concentrated hydrochloric acid is a liquid that fumes when it comes into contact with air. It is used as a flux for sheet metals of zinc-iron or galvanized sheets. This is also known as muriatic acid.

Zinc chlorides: Zinc chlorides are known as killed spirits. It is mainly used for soldering copper, brass and tin sheets.

Ammonium chloride or Sal-Ammoniac: It is a solid white crystalline substance used when soldering copper, brass, iron, and steel (cast iron sheets).

Phosphoric acid: It is mainly used as a flux for stainless steel.

Borax: It is used in various household laundry and cleaning products. A mixture of borax and ammonium chloride is used as a flux when welding iron and steel. Borax is also used mixed with water as a flux when soldering jewelry metals such as gold or silver.

Organic fluxes:

Resin: It is used for soldering copper, brass, bronze, tin plate, cadmium, nickel, silver and some alloys of these metals.

Tallow: It is a form of animal fat. It is used when soldering lead, brass, and electrical joints.