Coating materials such as paints, plasters, varnishes, glues, sizes, printing colours and plastic materials are rendered bactericidal by incorporating therewith a stable emulsion of oil and water, in which an organic microbicidal substance has been colloidally dispersed. Specified microbicidal substances are phenols, cresols, di-iodothymol, ortho - oxy - quinoline, formaldehyde solution, trioxy-methylene, paratoluene - sulphochloramine, hexyl - resorcinol, para-chloro-meta-cresol, tri-iodophenol, mono-sulphonic acids of naphthenes, ortho-phenylphenate of sodium, and a mixture of tricresol, formaldehyde and sulphophenate of zinc. According to an example, linseed oil is emulsified with water and potassium linoleate, and in this emulsion para-chloro-meta-cresol is colloidally dispersed. This emulsion will render paint microbicidal by simple intermixture.ALSO:Coating materials such as paints, plasters, varnishes, glues, sizes, printing colours and plastic materials are rendered bactericidal by incorporating therewith a stable emulsion of oil and water, in which an organic microbicidal substance has been colloidally dispersed. Specified microbicidal substances are phenols, cresols, di - iodothymol, ortho - oxy - quinoline, formaldehyde solution, trioxy-methylene, paratoluene - sulphochloramine, hexyl - resorcinol, para-chloro-meta-cresol, tri-iodophenol, monosulphonic acids of naphthenes, ortho-phenylphenate of sodium, and a mixture of tricresol, formaldehyde and sulphophenate of zinc. According to an example, linseed oil is emulsified with water and potassium linoleate, and in this emulsion para-chloro-meta-cresol is colloidally dispersed. This emulsion will render paint microbicidal by simple intermixture.ALSO:Coating materials such as paints, plasters, varnishes, glues, sizes, printing colours and plastic materials are rendered bactericidal by incorporating therewith a stable emulsion of oil and water, in which an organic microbicidal substance has been colloidally dispersed. Specified microbicidal substances are phenols, cresols, di-iodothymol, ortho-oxy-quinoline, formaldehyde solution, trioxy-methylene, paratoluene-sulphochloramine, hexyl - resorcinol, para-chloro-meta-cresol, tri-iodophenol, monosulphonic acids of naphthenes, ortho-phenylphenate of sodium, and a mixture of tricresol, formaldehyde and sulphophenate of zinc. According to an example linseed oil is emulsified with water and potassium linoleate, and in this emulsion para-chloro-meta-cresol is colloidally dispersed. This emulsion will render paint microbicidal by simple inter-mixture.