Sounds like the wood's oil soaked. Depending on extent you can make a paste of cat litter(the clay based kind). Use the cheapest unscented type and mix with solvent such as paint thinner or acetone. Use normal care when handling volatile solvents... This paste is spread on the wood and allowed to dry. It will absorb some of the oil from the wood. After it's dry, heat from a heatgun may be used to help force the opil from the wood. NOTE-After it's dry!! The dirty mix is then brushed or scraped from the wood and the process is repeated.. The stock can also be soaked in acetone. Be cautious as acetone is very volatile and higly flammable. It will also disolve nearly anything including the wood if left in too long..