1.1 ,This practice describes a solvent rub technique for assessing the MEK resistance of ethyl silicate (inorganic) zinc-rich primers. The MEK resistance of some two-component ethyl silicate zinc-rich primers has been shown to correlate well with the cure of the primer as determined by diffuse reflectance infrared spectroscopy.2 The technique can be used in the laboratory, field, or in the fabricating shop. Practice D5402 is the preferred method for organic coatings.