About metal materials for making faucets - Brass-Part2

Brass metal materials for making faucets

To comply with the new restrictions on lead, today's faucet brass uses other additives to ensure malleability. The most common substitute materials are bismuth and silicon.

Bismuth is similar to lead – right next to lead on the periodic table of elements – but it is not harmful to humans. Bismuth, however, is expensive. It is 300 times rarer than lead, even rarer than silver, which is the reason that bismuth-brass alloys are considerably more expensive than leaded brass.

Bismuth has several other problems. It is, unlike lead, a brittle metal, and requires a more precise casting process to preserve the ductility of brass. The result of improper casting is illustrated by a 2012 recall by the Consumer Products Safety Commission of 63,000 azimuth-brass ball valves made in China for use in natural gas pipelines. They were much too brittle resulting in cracks and dangerous valve failures.

Bismuth is also an environmental issue. Brass alloyed with bismuth cannot be easily recycled with non-bismuth brass and must be kept separate to avoid cross-contamination of the materials.

Silicon has somewhat similar recycling issues, but not as severe. Some alloys can be recycled with ordinary brass. Its chief advantage is that it is plentiful. It is not, however, less expensive.

Silicon-brass is considered a high-strength brass. The silicon increases resistance to wear and corrosion. Its disadvantages are that it requires a higher casting temperature than ordinary brass and its hardness makes it much more difficult to machine.

Plumbers don't care for it because it requires a hotter torch and special techniques to solder without which "cold" solder joints may spring a leak. Nonetheless, it is increasingly popular among faucet manufacturers. One alloy, Eco-brass™ (C69300), is especially formulated for plumbing fixtures.