Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fine-tuning fine art with lasers

11.09.2002


Art conservators have been slow to adopt lasers as restoration tools, preferring their trusty scalpels and solvents to untried technologies. But the first systematic study of the long-term effects of lasers on paintings should help ease their doubts: the results show that lasers can be superior restoration tools without sacrificing the safety of priceless works of art.



The findings are reported in the Sept. 15 print edition of Analytical Chemistry, a peer-reviewed journal of the American Chemical Society, the world’s largest scientific society.

European researchers studied the physical and chemical changes that occurred in various paint materials exposed to ultraviolet laser light, in order to address some of the unanswered questions about the effects of laser cleaning.


They found that lasers did no harm to paintings originally coated with varnish -- an extremely common practice with older paintings on canvas -- as long a very thin layer of varnish was left on the surface. For unvarnished paintings, chemical changes were few and easily controlled by manipulating the laser parameters. The study also showed the effects to be primarily photochemical -- initiated by light. This runs contrary to widespread concern that material adjacent to the laser beam could suffer damage from incidental heating.

The research is part of a cooperative project funded by the European Union to create a laser-based unit for cleaning valuable artwork.

The idea behind the project is that laser light, directed by a software-controlled workstation, can delicately remove varnish and dirt from paintings and painted artifacts, leaving the underlying pigments unharmed. The process can be monitored by a tool called laser-induced breakdown spectroscopy (LIBS), which analyzes the specific make-up of the plume produced by the laser as it removes material. This helps avoid damaging the artwork itself.

Over time, paintings accumulate dirt and soot; coatings of protective varnish grow hazy; and smugglers apply layers of paint to disguise their illicit freight. Natural disasters can also jeopardize precious national treasures, as illustrated by the recent flooding in Europe. While many cultural artifacts seem to have been spared from serious damage in the floods, conservators will probably have to deal with the effects of humidity and black crust formation, according to Marta Castillejo, Ph.D., a research scientist with the Spanish Council for Scientific Research and an author of the paper. "In some cases, lasers could be of help," she says, "especially when traditional methods fail."

Conventional cleaning techniques involve scalpels, messy solvents and painstaking labor, as conservators slowly peel back the layers of time. The chemicals involved can be harmful to the environment and dangerous if handled improperly.

Lasers offer many advantages over traditional methods, including the ability to focus on very small areas and greater control over the amount and type of material removed. They are also safe and environmentally friendly.

Invented in the early 1960s, lasers have since found widespread use in such diverse areas as metallurgy, medicine and even entertainment (e.g. the ever-popular Pink Floyd laser light show). Although art conservators first experimented with lasers in the 1970s, they have been slow to implement the technology, especially in the United States.

They maintain a skeptical attitude, and for good reason: no one wants to be responsible for charring a one-of-a-kind masterpiece. "They are concerned with long-term effects and also with the complications arising from the use of sophisticated, expensive equipment that ... requires special training for its proper use," Castillejo says.

Lasers initially found similar opposition in the medical field, but they have now replaced scalpels as the tool of choice for many surgeons. Castillejo sees this same shift occurring with the art conservator’s scalpel.

In the current study, the researchers used a krypton fluoride (KrF) excimer laser -- a pulsed-gas system that operates at a fixed wavelength in the ultraviolet spectrum -- to analyze a variety of pigments within the framework of a tempera paint process. "Egg tempera was the most important paint before oil paint was introduced in the 15th century," Castillejo says. "The pigments or colors are mixed with an emulsion of egg yolks rather than oil and can be thinned and solved with water."

Both organic and inorganic pigments were used in the experiment to provide a representative series used by traditional painters. Unvarnished samples were cured for a period of three weeks and then light-aged for four weeks to mimic real-aged paints. The varnished samples did not require artificial aging because shellac dries quickly.

Various analytical methods were used to study the chemical and physical changes that occurred in the paint samples. Profilometry determined changes on the paint surface; colorimetry measured the discoloration of the paint; and optical and vibrational spectroscopy and mass spectrometry detected chemical changes in the binding medium.

"There is a lot of interest among conservators in the development of a portable machine," Castillejo says. The existing prototype is not yet portable, but development is heading in that direction. And the workstation has been used successfully to clean several paintings that were damaged by fire.

Beverly Hassell | EurekAlert!
Further information:
http://www.acs.org/

More articles from Process Engineering:

nachricht Harder 3D-printed tools – Researchers from Dresden introduce new process for hardmetal industry
11.10.2018 | Fraunhofer-Institut für Keramische Technologien und Systeme IKTS

nachricht Flying High with VCSEL Heating
04.10.2018 | Fraunhofer-Institut für Lasertechnik ILT

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Epoxy compound gets a graphene bump

14.11.2018 | Materials Sciences

Microgel powder fights infection and helps wounds heal

14.11.2018 | Health and Medicine

How algae and carbon fibers could sustainably reduce the athmospheric carbon dioxide concentration

14.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>