I have had gunstocks that looked dry and clean and then would weep cosmo at the range out in the heat of the sun. I guess if it has had decades to soak into the wood, it ain't gonna flush out easy, like it was just on the surface. Apparently some folks just work at it awhile till they think they got most of it and then apply some non porous finish to the wood to hold in what might be left! If it was not a gunstock and something you really needed, for other purposes probably wood soaked in cosmo would be considered ruined and thrown away.