A method for improving operating conditions of a printing machine, said printing machine comprising: • a rotary impression cylinder (10, 30) having a support surface which supports a web substrate moved in a transport direction, • at least one pressure roller pressing said web substrate against said support surface of said impression cylinder (10, 30), said pressure roller providing an entry nip at which the web substrate first comes into contact with the support surface of the impression cylinder (10, 30), and • at least one printing unit having a printing cylinder arranged for printing ink on said web substrate supported on the impression cylinder (10, 30), printing ink on said web substrate supported on the impression cylinder (10,30), characterized in that the method comprises following steps: • support on the support surface a web substrate having a substrate width which is less than a maximum impression width of said support surface, said support surface exhibiting at least one non-covered area not covered by the web substrate adjacent to a side edge of said web substrate during printing; • applying, by a liquid applying unit controlled by control means, a liquid insoluble with the printing ink on the support surface of the impression cylinder (10, 30) upstream of said pressure roller, • adapt, by said control means, flow rate and distribution of the applied liquid to particular printing conditions said liquid forming a liquid layer on at least one non-covered area of the support surface of the impression cylinder (10, 30), said liquid layer providing an ink-repellent coating on said at least one non-covered area; • a rotary impression cylinder (10, 30) having a support surface which supports a web substrate moved in a transport direction, • at least one pressure roller pressing said web substrate against said support surface of said impression cylinder (10, 30), said pressure roller providing an entry nip at which the web substrate first comes into contact with the support surface of the impression cylinder (10, 30), and • at least one printing unit having a printing cylinder arranged for printing ink on said web substrate supported on the impression cylinder (10, 30), printing ink on said web substrate supported on the impression cylinder (10,30), characterized in that the method comprises following steps: • support on the support surface a web substrate having a substrate width which is less than a maximum impression width of said support surface, said support surface exhibiting at least one non-covered area not covered by the web substrate adjacent to a side edge of said web substrate during printing; • applying, by a liquid applying unit controlled by control means, a liquid insoluble with the printing ink on the support surface of the impression cylinder (10, 30) upstream of said pressure roller, • adapt, by said control means, flow rate and distribution of the applied liquid to particular printing conditions said liquid forming a liquid layer on at least one non-covered area of the support surface of the impression cylinder (10, 30), said liquid layer providing an ink-repellent coating on said at least one non-covered area; • support on the support surface a web substrate having a substrate width which is less than a maximum impression width of said support surface, said support surface exhibiting at least one non-covered area not covered by the web substrate adjacent to a side edge of said web substrate during printing; • applying, by a liquid applying unit controlled by control means, a liquid insoluble with the printing ink on the support surface of the impression cylinder (10, 30) upstream of said pressure roller, • adapt, by said control means, flow rate and distribution of the applied liquid to particular printing conditions said liquid forming a liquid layer on at least one non-covered area of the support surface of the impression cylinder (10, 30), said liquid layer providing an ink-repellent coating on said at least one non-covered area;