The use of a developer is required by most penetrant inspection testing specifications. The developer draws the penetrant from the flaw and creates a uniform surface on which to view the penetrant indication. D-70 is used with fluorescent penetrants as form “d” and with visible penetrants as form “e”. It is applied after the surface penetrant has been removed and the inspection surface dried. D-70 nonaqeous developer consists of absorbent powder suspended in a volatile solvent. The developer particles will settle out upon standing, requiring agitation prior to application. This type of developer is most commonly used in aerosol cans, but may also be bulk sprayed using a paint sprayer. The solvent action of this type of developer helps bring the penetrant to the surface enhancing the detectability of the finest flaws. This type of developer uses flammable solvents and should not be used in confined spaces or near open flames or sparks.