Abstract: The present invention also provides two methods of preparing the antimicrobial preparation comprising the steps of submerging the porous material in vacuum vessel containing a solution comprising 1% to 4% of silver-chitosan dissolved in an organic acid; applying a vacuum to the vacuum vessel to displace air from the porous material; removing the vacuum from the vacuum vessel to return it to atmospheric pressure and then either drying the material and coating the material with a crosslinking solution or heating the material to between 120° C. and 140° C.