Remove old shellac from woodwork by stripping the wood surface with denatured alcohol, using chemical strippers or sanding away the old finish. The most effective method may depend on the condition and thickness of the shellac being removed.
For furniture manufactured after 1930, begin with denatured alcohol. Most shellacs are alcohol-based and some of the solvent on a rag typically loosens the finish and does not damage the wood. A lacquer thinner is also an option.
Tougher finishes may require sanding, which removes a layer of the wood as well but is a quick and effective method for removing shellac. Chemical strippers such as those containing methylene chloride are effective but are highly caustic. They require a well-ventilated work area, or the user may risk damage to his eyes, skin and respiratory system.