I have never done any type of extensive leather or plastic repair but I have looked into the process as I am considering adding leather/vinyl repair as a service.
Bottom line. If it is just on the steering wheel it would probably be cheaper/easier to just replace the damaged part as opposed to buying all the necessary tools/chemicals needed to repair it. If you were doing more than one vehicle the cost equation would make much more sense...
Even so, from what I understand, it is possible to achieve an absolutely perfect repair with an OEM look and finish. The steps would be similar to this:
1: Strip surface of any dressings or silicone.
2: Fill defect with a special plastic filler and sand until level.
3: Create a copy of the texture pattern from another part of the surface using special compounds, hardeners & texture pads.
4: Apply texture coating.
5: Imprint the copied texture that you just created.
6: Heat with a blow dryer to fully/quickly cure the repaired area.
7: Dye the area with a color-matched dye.
8: Seal the repaired area.
On the other hand you could always just throw some DLUX on there and call it good.

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