Open Access proceedings Journal of Physics: Conference series

1234567890‘’“”
Florence Heri-Tech – The Future of Heritage Science and Technologies 
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 364 (2018) 012078 doi:10.1088/1757-899X/364/1/012078
Figure 6 - The laser acting on a drawing in the Carracci Gallery in Palazzo Farnese in Rome 
(courtesy of Paolo Pastorello-CRC Restauri). 
3.4. Laser cleaning of easel paintings 
The cleaning of easel paintings i.e. the removal of thin films of varnishes, resins, repaintings or 
deposits from the pictorial layer, represents the main challenge of laser cleaning.
Recently, the interest turned to the Er: YAG laser systems with a wavelength of 2940nm which 
proved to be particularly effective in the removal of repaintings and aged, yellowish varnishes from 
paintings on canvas and board [34, 35]. The wavelength of 2940nm is highly absorbed by OH bonds 
therefore, the efficiency of the laser ablation is directly proportional to the amount of OH groups 
present in the materials. When these OH bonds are not present on the original material, they can be 
obtained by the addition of hydroxylated liquids, which can also help to limit the heat penetration. 
The application of Er:YAG laser cleaning to easel painting is the newest frontier of this technique. 
There are quite few case studies reported in literature [36] and a scientific, rigorous approach is still at
its initial stage but the interest has enormously increased in the last period thanks to some successful 
cleaning results obtained on the removal of mastic and dammar varnishes, linseed oil/ sandarac 
varnishes, Paraloid B72 and animal glue. 
Restorers, conservators and scientists are working together to fully exploit the huge potential of this 
brand new approach that will surely bring a new important tool in the restorer’s toolbox: the laser. 
Figure
7 - Duke University professor Adele De Cruz using the Er:YAG laser for the 
removal of aged varnish from a Borrassa’s Panel Painting (15th Century). 

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1234567890‘’“”
Florence Heri-Tech – The Future of Heritage Science and Technologies 
IOP Publishing
IOP Conf. Series: Materials Science and Engineering 364 (2018) 012078 doi:10.1088/1757-899X/364/1/012078