Could you advise on whether it’s appropriate to strip old doors?

QThis recent practice is generally inappropriate historically and can cause harm. Most old doors comprise softwood that was originally painted. An exception is pre-18th-century oak doors that, where not limewashed, could be left unpainted. Additionally, sandblasting may spoil the surface of timber. Dipping in ‘acid baths’ can raise the grain and, by softening the glue, weaken joints.