Talcum powder itself does not "set off" a traditional metal detector, but it is a primary target for Powder-Based Substance (PBS) screening protocols implemented by the TSA and international agencies like the UK's CAA. Since 2018, travelers are generally required to place "powder-like substances" greater than 350ml (roughly 12 ounces) in a separate bin for X-ray screening, similar to how liquids are handled. If the powder is opaque on the X-ray or appears in a large volume, security officers will likely perform a manual inspection or an Explosive Trace Detection (ETD) swab to ensure the substance is not a precursor for explosives or illicit narcotics. While talcum powder is a common household item, its fine particulate nature can look suspicious on imaging. To avoid delays, it is recommended to pack large containers of talc in your checked baggage rather than carry-on, or ensure it is in its original, clearly labeled retail packaging to simplify the verification process for the agents.