Iron powder has previously been demonstrated to be a potential dry cleansing agent for oiled feathers, whereby both the oil ad(b)sorbing particles and the contaminant may be harvested magnetically. Previous studies on feather clusters have only been able to achieve 97.4% removal. While impressive, this is not considered to be entirely satisfactory for wildlife rehabilitation in practice. Reported in this Technical Note is a series of experiments designed to establish whether a grade of iron powder can be identified that is capable of achieving 100% removal and to identify those characteristics responsible for such improvement. To this end, the abilities of nine different grades of iron powder to remove four different contaminants (three crude oils and a crude oil/seawater emulsion) from feather clusters have been compared, as have the relative physical characteristics of the different iron powders. It has been established that the efficiency of remediation is indeed related to certain physical attributes of the particles (the “grade”). Specifically, a spongy superfine iron powder has been identified that is capable of achieving 100% removal (within experimental error) for all four contaminants tested. This represents an important proof of principle that makes the development of a practical field device a real possibility.