This document is a report of filter characterization tests performed on a set of filter breadboards representative of two of the Athena X-IFU thermal filters, namely the THF2 mounted on the 2K aluminum shield, which is a Faraday cage, at 150 mm from the microcalorimeter focal plane array, and the THF300 the larger and outer thermal filter mounted on the main shield of the cryostat which is also a Faraday cage. Such filter breadboards have undergone the same tests performed on similar filter samples based on the polyimide/Al baseline technology
