What are the properties of dry powder and wet suspension magnetic particles?
They are iron oxide particles, finely divided in sizes varying between 0.125 and 60 microns with a high permeability (easily magnetized) and low retentivity (ability to stay magnetized). Dry particles are chemically dyed to provide contrast against the background of the test surface. Stock colors are gray, red, black and yellow. Application is either with a squeeze bulb or spray gun. Wet suspension particles are suspended in an oil-based or water-based liquid vehicle or carrier. With water, operators must add conditioners in addition to a wetting agent and corrosion inhibitors.
