A mixer system for producing topcoat compositions and filling compounds which has a volumetric or gravimetric metering plant as a mixing apparatus and at least the following components (a) to (d): at least one pigment-free component (a) for producing at least one topcoat composition (A); at least one component (b) different from (a), for producing at least one coating composition (B) used as a filling compound; a plurality of different pigment pastes (c) different from the components (a), (b), and (d), which in each case independently of one another include at least one binder (c1), at least one organic solvent (c2), and at least one pigment (c3); and a plurality of different, binder-free dye solutions (d). A process for producing topcoat compositions and/or filling compounds with the mixer system, and a method of repairing defects on or in wood with the topcoat compositions and/or filling compounds.