Cut away any loose fibers, strings or small pieces of leather in the damaged area using scissors.
Sand the damaged area to further remove damaged leather and to smooth it for treatment. First, sand the area using 320p sandpaper for debris removal then sand it again using 1200p sandpaper to smooth down the surface.
Clean the sanded area using an alcohol-based leather cleaner and a cleaning cloth. Let the cleaner evaporate from the damaged area for at least 10 minutes before proceeding with treatment.
Cover the damaged areas with heavy leather filler applied with a palette knife. Allow the filler to dry for five minutes and then sand the area with 1200p sandpaper to further work the filler into damaged areas.
Dab leather colorant into the treated area using a sponge. Apply one even coating and allow it to dry for five minutes before applying a second coating.
Examine the leather after the second coating of colorant has dried. Occasionally the damage appears just as prominent or worse. If this occurs, apply another layer of filler followed by two more layers of colorant. If the damage appears lesser or gone, proceed to the next step.
Apply a coat of lacquer to the treated leather to restore shine. Allow the lacquer to dry on the sofa for several hours or overnight before using the sofa.