surface or the efficient formation of free radicals on the surface generating the possibility of intermolecular cross linking carbonization in the etching process it is likely that the etching exposes internally melted additives such as activated carbon colorants and other possible additives that further aid in filtration the increased surface area can enhance filtration properties by post charging of the media through conventional electret charging equipment as an alternative mechanism it is likely that cleaning the surface removes oily residues from the surface of the microfibers allowing better filtration by exposing the surface to the particles to be filtered the process may also increase the amount of additives from the interior at the surface of these microfibers additionally or alternatively the instant invention allows more surface area exposed per weight than does previously disclosed methods all of which improves the filtration process irrespective of the mechanism the net result of the instant invention is that there is an increased surface area of the fibers available for filtration allowing more u201c sights u201d or area for particle entrapment thus leading to a more effective filter the instant invention also does not require the higher ratio of additives of previous methods yet it is still effective at filtering the desired particles thus the instant method.