Brass is an alloy made by combining copper and zinc. Apha brasses contain less than 35% zinc, making it relatively easy to work even when the brass is cold. Alpha-beta's zinc content is 35% to 45% zinc. This type of brass can be worked when hot. Beta brass, consisting of 45% to 50% zinc, should only be worked when hot. Beta brasses are stronger and harder than alpha or alpha-beta brasses. White brass is more than 50% zinc. It is very brittle and not generally used.