Gołuchów Castle, branch of the Poznań National Museum
18th-century fireplace from the bedroom of Princess Marguerite Adélaïde of Orléans, 2017
A sandstone fireplace preserved in relatively good condition.
It bears traces of previous treatment with artificial resins, which caused local yellowing. The fireplace was heavily soiled.
Restauro was tasked with cleaning the soiling and other deposits off the fireplace. As the fireplace is located in the historic interior of a museum featuring valuable exhibits, no traditional treatment methods could be applied, which require water supply or emit dust. Hence, a decision was made to apply a laser system.
The process of selecting optimum laser beam parameters based on the assessment of changes in the color and clarity of the stone surface was monitored using a spectrophotometer.
The fireplace was cleaned efficiently and effectively with an Nd-YAG Q-switch laser system, using two different wavelengths, i.e.:
- 1064 nm with an energy density of 1200 mJ/cm2 – applied to the entire surface, and
- 532 nm with an energy density of 300 mJ/cm2 – applied to places which remained yellow despite previous cleaning.