Cerrobend

Cerrobend®, made by Cerro Metal Products, is also known as Wood's metal, Bend alloy, or pewtalloy. Or even Lipowitz Metal in Europe.

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It is a eutectic fusible alloy of bismuth, lead, tin, and cadmium, known for its low melting point of 70 °C (158 °F). Molten Cerrobend can be held in an unprotected hand (though not without considerable discomfort).

It is named for its primary use as a filler when bending thin-walled metal tubes. For this use the tubing is filled with molten Cerrobend. Once the Cerrobend hardens the tubing is bent, the filler preventing collapse of the tubing. The Cerrobend is then removed by heating, often by simply boiling in water.

Cerrobend also has uses for making custom-shaped apertures and blocks (e.g., electron-beam cutouts and lung blocks) for medical radiation treatment, and making metal inlays in wood.

A similar alloy is called Cerrosafe®. This non-eutectic alloy melts at 165 °F (74 °C). Its main use is by gunsmiths, for making a reference casting of the chamber of a firearm. When it solidifies it first shrinks, allowing its easy removal from the chamber. When it cools it expands back to the exact size of the chamber. The Cerrosafe casting can then be easily and directly measured with calipers or a micrometer to determine the exact dimension of the weapon's chamber, which is important for safety.

Alloys with even lower melting temperatures are Cerrolow® 136 and Cerrolow 117 that melt at 136 °F (58 °C) and 117 °F (47 °C) respectively. The Cerrolow alloys are eutectic alloys.

Their compositions are as follows:

Cerrobend Tin 13.3%, Bismuth 50%, Lead 26.7% Cadmium 10%

Cerrosafe Tin 11.3%, Bismuth 42.5% Lead 37.7% Cadmium 8.5%

Cerrolow 136 Tin 12% Bismuth 49% Lead 18% Indium 21%

Cerrolow 117 Tin 8.3% Bismuth 44.7% Lead 22.6% Cadmium 5.3% Indium 19.1% (source Birchon's Dictionary of Metallurgy London 1965; Experimental techniques in low-temperature physics By G. K. White, Oxford University Press, Third Edition.)