I followed the instructions that came with my Brooks B17 for years. Never do this.
"Proofide is the only substance that should be used to care for your saddle. Apply a little Proofide to the finished side of the leather. Allow the Proofide to permeate until dry and then polish off."
As a result I sat on a piece of oak for six years. Go and bugger yourselves, Brooks. You and your ten quid tin of Kiwi neutral shoe polish.
I was given the tip of painting on flexalan recently, and it's finally rideable, and enjoyable.