Old post...but.......
The old furniture makers and stock makers used "Whiting", which is calcium carbonate, a flour-like powder.
They'd mix the whiting with a solvent and warm the wood. The oils and grease "boil out" and before it can soak back in, the whiting wicks it up and absorbs it.
The whiting turns all colors of orange and brown.
Brush off and repeat.
When it was still available in America, we used Trichloroethane or "Clorathane" which is a SUPER degreaser. The fumes smelled like a spark within 100 yards would have caused a fireball, but the stuff was nominally non-inflammable.
Unfortunately, the EPA decided it was hazardous and banned it in the US.
This stuff was so volatile, it would absorb through your skin and get you high.
The headache following was awful so no one tried huffing the stuff.
It was such an effective degreaser, it would extract the skin oils from your skin and turn your hands white.
I'd mix the clorathane and whiting to a pancake batter consistency and paint the wood, inside and out, about 1/3 of the stock at a time.
Then I'd use a heat gun on Low or an electric stove burner to warm the wood.
Usually, 3 treatments would turn an absolutely black stock back to it's original walnut color.
These days, I'd probably use lacquer thinner or Acetone to mix the whiting, coat all the wood, then seal in a black solvent-proof bag and put on a roof or driveway in the summer sun.
Brownell's still sell whiting:
http://www.brownells.com/.aspx/pid=1133/sku=083-032-100/Product/OLD_FASHIONED_WHITING