Because polychromy of wooden sculptures relies on much the same techniques as panel paintings, the conservation problems are very similar.
Over the centuries many wooden polychrome sculptures fell victim to unprofessional treatments such as primitive repairs, alterations, overpainting, overgilding or were simply stripped of their decoration to reveal the bare wood.
In addition to being painted, polychromed sculptures are also very often gilded. Such complex, multilayered surfaces are extremely delicate and sensitive.
Details in conservation/restoration measures see: Services/Sculpture conservation