The typical process for annealing copper sheet metal involves heating it to a cherry red color and then allowing it to cool slowly in air. Annealing is a heat treatment process that softens the metal, making it more ductile and easier to work with. By heating copper to a cherry red state, which is approximately 1,600°F to 1,800°F, the internal structure of the metal is altered, reducing hardness and relieving stresses caused by previous fabrication processes.
Once the copper has reached the required temperature, it is crucial to let it cool slowly in air. This gradual cooling helps in achieving desired mechanical properties and ensures that the metal does not become brittle or develop new stress patterns, which could compromise its effectiveness as a gasket.
Although other methods like cooling quickly in water, heating and leaving in open air, or using copper directly without annealing are common in some materials or applications, they do not effectively achieve the desired softness and ductility needed for producing high-quality gaskets from copper sheet metal. Each of these alternative methods may cause issues such as increased hardness or the retention of internal stresses, making them unsuitable for gasket applications where flexibility and precision sealing are critical.