Allow the spackling compound to dry completely. Sand the spackle as close to the surface as possible by rubbing it with sandpaper. Once you wear the spackle down to a thin coating, stop sanding to avoid scratching the wood.
Sweep the spackle dust off the wood with a whisk broom. Dampen a cloth, and wipe the wood to remove the remaining dust.
Moisten a clean cloth with a quarter-sized amount of linseed oil. Place the linseed oil cloth over the remaining spackling compound. Leave the cloth in place for three to five minutes to soften the spackle.
Rub the wood with the cloth to remove as much of the softened spackle as possible.
Pour 3/4 teaspoon of linseed oil into a bowl. Add 1 teaspoon of rottenstone powder. Stir the two ingredients.
Apply the rottenstone paste to the remaining spackling compound. Rub the paste in circular motions to remove the spackle.
Wipe off the rottenstone paste and last traces of spackling compound with a damp cloth. Clean the surface with wood cleaner to remove any residue from the rottenstone paste. Buff the wood surface dry with a clean cloth.