Efficacy of laser cleaning in the removal of biological patina on the volcanic scoria of the rock-hewn churches of Lalibela, Ethiopia

Taye, Blen; Lahoz, Ruth; Caldeira, Ana Teresa; Schiavon, Nick

doi:10.1007/s12665-017-7223-3

Cited by 20 publications

(13 citation statements)

References 38 publications

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“…However, the authors noted that biotite was damaged by melting, even at fluences ≤1.5 J/cm 2 . The UNESCO Ethiopian Lalibela church façades attacked by a microbial community constituted by bacteria, fungi, and lichens have been treated with laser cleaning to avoid abrasive particles or chemicals, minimizing the risk of damaging the fragile stone [ 74 ]. Lichen encrustations on basaltic stone were removed with UV laser pulses (355 nm) at a fluence of 0.35 J/cm 2 .…”

Section: Physical Methodsmentioning

confidence: 99%

The Control of Cultural Heritage Microbial Deterioration

2020

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The microbial deterioration of cultural heritage includes physical and chemical damage as well as aesthetic alteration. With the technological advancement, a plethora of techniques for removing unwanted microorganisms have opened up new opportunities for microbiologists and conservators. This article reviews the most applied, up-to-date, and sustainable techniques developed for the control of cultural heritage microbial deterioration presenting noteworthy case studies. These techniques include chemical methods, i.e., traditional biocides and nanoparticles; physical methods, such as mechanical removal, UV irradiation, gamma radiation, laser cleaning, heat shocking, microwaves, and dry ice treatment; and biological methods, such as natural molecules with biocidal activity, enzymes, and microorganisms. The application of control systems requires the comprehension of their behavior toward the unwanted microorganisms and possible interactions with the heritage materials. This overview shows also the control methods drawbacks for the purpose of creating awareness in selecting the most suitable technique or combination of techniques.

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Section: Physical Methodsmentioning

confidence: 99%

The Control of Cultural Heritage Microbial Deterioration

2020

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“…This new technique seemed very promising for conservation treatments at a time where heritage objects needed cleaning more frequently [2]. Since Asmus' works, many studies on laser cleaning have been conducted and explored the differences induced by changing the laser parameters such as the emitting wavelength, the laser energy, and the pulse duration on different materials and various contaminants including biological colonization (lichens, algae) [3][4][5][6][7][8][9][10][11][12][13][14], black sulphated gypsum crusts [15][16][17][18][19][20][21][22][23][24], dirt and environmental soiling [25], corrosion products [26][27][28][29][30][31][32][33][34], or graffiti [35][36][37][38][39][40][41][42][43][44][45][46][47]…”

Section: The Development Of Laser Cleaning For Heritage Conservationmentioning

confidence: 99%

Towards safe and effective femtosecond laser cleaning for the preservation of historic monuments

et al. 2023

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We explore femtosecond laser cleaning of materials used in the construction of historic monuments, such as stone and steel covered in typical contaminants caused by harsh environments that may be found in urban areas. We address the cleaning of these materials from a conservation perspective, taking as examples the preservation and cleaning of iconic structures such as the steel and the granite of the Sydney Harbour Bridge, Hawkesbury sandstone, a popular building material of a variety of monuments in Sydney (Australia), Makrana marble taken from the Soami Bagh Samadh temple of Agra in India, and also graffiti removal. We demonstrate that femtosecond laser pulses can clean a range of different contaminants such as biofilm, environmental soiling, rust, and spray paints, while preserving the integrity of the underlying substrates. Femtosecond laser cleaning is a fast and effective method and a safer alternative to lasers with longer pulse durations for the preservation of historic monuments.

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“…Conventional conservation techniques for Cultural Heritage (CH) materials usually include chemical and mechanical cleaning methods that have been employed for centuries. In contrast, laser cleaning techniques may be included as an outstanding and encouraging example of how relatively recent technological advances may be applied to improve conservation methods for CH materials [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Sub-ns-pulsed laser cleaning of an archaeological bone from the Sierra de Atapuerca, Spain: a case study

et al. 2021

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Controlled laser irradiation parameters using recently developed sub-nanosecond pulsed laser technology with emission wavelength in the near Infrared regime (1064 nm) have been assessed on a Pleistocene bone from the archaeological site of Sierra de Atapuerca, Spain. Burst pulse mode was employed to explore contaminant removal efficiency, while at the same time, assessing the degree of damage produced to the underlying original substrate surface. The surface morphology and composition of the deteriorated bone have been characterized, along with the effects of laser irradiation at 1064 nm, using Optical Microscopy (OM), Scanning Electron Microscopy–with Energy Dispersive X-ray Spectrometry (SEM–EDS), and X-ray Photoelectron Spectroscopy (XPS). The most effective laser cleaning parameters in burst mode have been identified in order to optimize the emission parameters of the laser, thus localizing its interaction within the outermost layers of contaminants and degradation products, avoiding damage to the underlying original bone surface. Hence, threshold cleaning and substrate damage values have been determined for this new sub-ns laser, paving the way to safer laser cleaning procedures that may be useful for the effective conservation of bone archaeological artifacts.

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Efficacy of laser cleaning in the removal of biological patina on the volcanic scoria of the rock-hewn churches of Lalibela, Ethiopia

Cited by 20 publications

References 38 publications

The Control of Cultural Heritage Microbial Deterioration

The Control of Cultural Heritage Microbial Deterioration

Towards safe and effective femtosecond laser cleaning for the preservation of historic monuments

Sub-ns-pulsed laser cleaning of an archaeological bone from the Sierra de Atapuerca, Spain: a case study

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