Silver compositions and methods for making biocidal currency

An intaglio printing ink composition, comprising:

• a non-aqueous vehicle;
• an optional co-solvent;
• a colorant;
• the improvement which comprises adding to said composition a biocidally effective amount of biocidal silver, said biocidal silver being selected from the group consisting of elemental silver, nanoparticulate silver, colloidal silver, and inorganic silver and silver ions;
• wherein
• said biocidally effective amount of biocidal silver is an amount of biocidal silver that results in an amount of silver being present on the surface of a currency substrate after printing that neutralizes or destroys bacteria and viruses;
• and wherein said non-aqueous vehicle comprises a hydrocarbon solvent, wherein the hydrocarbon solvent is present in about 47% by weight with respect to the total content of the ink, said colorant comprises channel carbon, wherein the channel carbon is present in about 57% by weight with respect to the total solids content of the ink, and wherein said biocidal silver is present in an amount of from about 0.1 ppm to about 50 ppm measured as the weight of silver.