Reasons for impurities
Brass is an alloy of copper and zinc, but may contain small amounts of iron impurities during the actual production process. These iron impurities may come from raw materials, such as iron mixed in with the scrap metal used, or during the melting process when iron from the melting equipment is incorporated into the alloy. When the level of iron impurities reaches a certain level, it causes brass to exhibit properties that can be attracted to magnets.

Processing factors
During the processing of brass, such as casting, forging or machining, there may be foreign iron filings, iron powder, etc. attached to the surface of brass products. If these iron components are not completely removed, it can also cause brass products to look as if they are able to be attracted by magnets. For example, after machining brass parts on a lathe, if the parts are not adequately cleaned, iron residue on the lathe may cause the parts to become magnetic.

Special Brass Components
Some specialty brass alloys have small amounts of iron added to improve certain properties. For example, iron brass is a special brass alloy in which the iron content can be within a certain range (e.g., around 0.3 – 1.2%), and this brass alloy contains iron components that are naturally attracted to magnets. The purpose is to improve the properties of brass such as strength, hardness and corrosion resistance.