Various factors influence the actual operating sensitivity at which a metal detector is able to perform reliably. The ease of detection depends on the magnetic properties and electrical conductivity of the metal. Ferrous metals are both magnetic and good electrical conductors, so they are easily detected. Non-ferrous metals are generally good conductors, so they are relatively easy to detect. Stainless steels are usually non-magnetic and poor conductors of electricity, which make them harder to detect.
Salty and moist products, including meats, can conduct electricity that will affect the metal detector in the same way as a metal contaminant. “Product effect” is the term used to describe instances in which a product’s characteristics affect the metal detector in the same way as a metal contaminant. Moisture and salt content vary from animal to animal. Different cuts of beef, for example, may have different levels of moisture and salt, further complicating matters. Product size, consistency and orientation through inspection can also generate product effect.