Post emulsifiable Penetration System:
Post emulsifiable lipophilic/ hydrophilic methods are formulated to maximize penetrating and visibility characteristics. They do not contain any emulsifying agent in penetrant and cannot be completely removed with plain water.
Post emulsifiable lipophilic: Removal is made possible by applying an emulsifier in a separate process step after dwell time for penetrant. This converts the excess surface penetrant into an water washable penetrant . This emulsifier uses diffusion method to convert penetrant in to water washable.
Post Emulsifiable Hydrophilic Method: The hydrophilic postemulsifiable, method also uses penetrants requiring a separate emulsifier. The penetrants are the same as those used in the lipophilic method. The difference between hydrophilic and lipophilic methods is in the emulsifiers. Hydrophilic emulsifiers are water soluble emulsifiers and actually remove excess surface penetrant by means of a scrubbing action rather than diffusion action.