GOŁUCHÓW CASTLE, LOCAL BRANCH OF THE POZNAŃ NATIONAL MUSEUM
FIREPLACE IN THE POLISH CHAMBER, 2018
In terms of integrity, the stone architectural details of the Polish Chamber were in a good condition. However, they were covered with dirt and other deposits, adversly affecting their original artistic value and thus also their appeal to visitors. The gilding on the finely sculpted, convoluted relief decorating the Chamber’s fireplace was poorly preserved.
The objective of the project was to restore the esthetic value of the fireplace through removal of dirt and deposits by means of laser ablation, a method which involved a risk of damaging the gilding during treatment. To mitigate it, a series of trials were carried out to establish optimum, safe laser beam parameters. As a result, it was determined that gilded and bare stone would be most effectively, yet absolutely safely, treated if the laser beam was applied sequentially with variable parameters, i.e.:
- a beam with a wavelength of 532 nm, energy density of 400 mJ/cm2, and frequency of 20 Hz/s to bare stone surfaces, and
- a beam with a wavelength of 1064 nm, energy density of 300–320 mJ/cm2, and frequency of 20 Hz/s to gilded stone surfaces and surfaces with a surviving ochre substrate.