c the calcining time is not critical it can be based upon the size the articles quaternary ammonium organosiloxane salt herein referred to as quaternary ammonium salt used as algaecide by coating on a fibrous material as shown in u s pat nos 3 817 452 and 3 865 728 forms no part of this invention rather this invention provides a new method of preparing an antimicrobial article moreover the article kills not only algae but also bacteria the relevant portions of the above patents are incorporated herewith by reference in the process of this invention the quaternary ammonium salt is dissolved in water to form a moiety of u2014 si oh 3 and the preformed substrate is soaked in the solution the moiety of the quaternary ammonium salt reacts with the sio 2 of the substrate thereby forming a strong bond 3 trimethoxysilyl propyldimethyloctadecyl ammonium chloride is representative of the group of is representative of the group of silyl quaternary ammonium salts that may be used in the instant application it has been found that in the process of making the organic antimicrobial article of this invention a special calcining aid can be used to enhance the adhesion or bonding of the quarternary ammonium salt to the preformed substrate the calcining aid is aluminum oxide.