Daniele Ciofini | Consiglio Nazionale delle Ricerche (CNR) (original) (raw)

Papers by Daniele Ciofini

JPhys photonics, May 15, 2024

Journal of Cultural Heritage, Feb 29, 2024

CRC Press eBooks, Oct 12, 2023

Journal of Cultural Heritage

Zenodo (CERN European Organization for Nuclear Research), Nov 18, 2019

Naturally occurring diterpenoid resins were extensively applied, mainly as oily mixtures, through... more Naturally occurring diterpenoid resins were extensively applied, mainly as oily mixtures, through the ages as protective and decorative coatings on paintings, metals and wood artifacts. When these coatings age, tend to generate tougher films than triterpenoid resins, completely insoluble, increasingly subject to darkening, and then very hard to remove using conventional methods. In this regards, laser sub-micrometric ablative techniques are being increasingly used in the cultural heritage field also for the treatment of synthetic and natural polymer coatings. Here, in the wake of the positive outcomes achieved on triterpenoid resin films, the present approach has been applied and extended to diterpenoid resin coatings, which have never been thoroughly studied yet. In detail, colophony, sandarac and Manila copal resin films, prepared as solvent and linseed oil formulations, were subject to light-ageing and then systematically irradiated at various exposure conditions using the 4 th (266 nm) and 5 th (213 nm) harmonics of a Q-Switched Nd:YAG laser. UV-Vis absorption spectroscopy was used as preliminary characterization of the films optical properties. The assessment of physico-chemical modifications induced by artificial light-ageing and ns UV laser irradiation were assessed non-invasively by µ-Raman spectroscopy, Laser Induced Fluorescence (LIF) and microscopic examination. The results underlined that, due to the presence of a polymer network, sandarac and copal resin coatings showed higher F th than those composed of colophony. Morphologically, all the coatings were subject to bubbling upon 266 nm irradiation, while damage-free at 213 nm. At molecular level, irradiation at 266 nm produced minor changes to ν(CH 3)/ν(CH 2), ν(C=O) and ν(C=C) modes, thus confirming an ablation mechanism mainly driven by photo-thermal bond-breaking through the ejection of gaseous by-products. Raman background fluctuations along with shifting and broadening of LIF maxima were supportive in the assessment of laser-induced surface modifications. Finally, the work performed indicates that the 213 nm wavelength is the most indicated for the treatment of aged solvent and oil diterpenoid-based coatings, as no side effects occurred. This outcome, corroborated by the previous results obtained in triterpenoid resin films, may have important implications in the field of cultural heritage conservation, as it extends the application range of solid-state Nd:YAG lasers to all types of protective and decorative terpenoid coatings.

CRC Press eBooks, Oct 12, 2023

In this work, Vis-NIR steady-state photoluminescence (PL) emission and Vis-NIR reflection spectro... more In this work, Vis-NIR steady-state photoluminescence (PL) emission and Vis-NIR reflection spectroscopy were used in order to investigate the effects induced on modern paint layers by LQS Nd:YAG(1064 nm) laser at subablative fluences. Cadmium yellow (Cdy), lithopone white (Liw) and chromium oxide green (Crg) pigments with and without oil matrix were investigated. The setup proposed allowed collecting reliable information on PL, color and morphology changes upon laser irradiation. Furthermore, the results achieved led to recognize, for the first time, the oil matrix alteration as the early trigger of the photothermal effects.

On the wake of recent successful applications of LQS Nd:YAG (1064 nm) laser in conservation of mo... more On the wake of recent successful applications of LQS Nd:YAG (1064 nm) laser in conservation of modern easel paintings, here, we focus on the study of undesired side effects of the laser treatment that can occur in photosensitive modern paints. Understanding the<br> phenomenology and nature of their alterations has a crucial importance for extending the laser approach in conservation. In the present work, a measurement methodology for characterising the sub-ablative effects of photosensitive paint layers was developed. The analytical approach was refined by considering the example case of cadmium yellow. CdS-based paint mock-ups using different oily binders were prepared and systematically laser irradiated under an epifluorescence microscope coupled to a spectrometer. The latter, image analysis, and ESEM-EDX allowed to collect information on the alteration phenomenology. The method provided underlines the strict dependence of the damage nucleation on the distribution of the pig...

With the aim of finding less invasive and selective cleaning strategies for paintings restoration... more With the aim of finding less invasive and selective cleaning strategies for paintings restoration, this thesis provides novel insights and successful applications on the use of pulsed Nd:YAG lasers to safely remove aged varnish coatings and overpaint layers. The laser-material interaction under different irradiation conditions of several painting materials, such as terpenoid-based varnishes and oil paint layers, was extensively characterized using different analytical techniques. Laser ablation tests carried out on a large number of naturally and artificially aged varnish samples using the fifth (213 nm) and fourth (266 nm) harmonics of a Q-Switch (15 ns) Nd:YAG laser evidence the fundamental importance of following a wavelength-based approach for the selective removal of painting varnishes. The promising results achieved on samples irradiated at 213 nm envisage very good prospects for the transfer of this laser cleaning approach in the field. Similarly, Long Q-Switching Nd:YAG (1064 nm) laser with a pulse duration of 120 ns was successfully tested for dealing the conservation problems of two female portraits dated around 1930 and 1910, respectively. The latter painting was found on the backside of a signed artwork by Giacomo Balla, one of the founding members of the Futurist Painters. These artworks were almost completely disguised by thick layers of oil overpaintings, which did not have any artistic relevance. Thorough characterization of the original pigments, binders, overpaintings and deterioration mechanisms allowed performing the complete restoration of the painting from Balla's studio, which returned an unknown Pre-Futurist artwork, and to plan that of the other female portrait by anonymous. At the same time, a systematic laboratory experimentation on prepared samples simulating the uncovering problems encountered in the real case has been carried out. This improved the knowledge of the laser induced-effects and ablation processes on different modern pigments and allowed to exploit such features for the selective removal of the undesired layers. The results reported disclose a significant application perspective for Nd:YAG laser ablation in conservation of modern easel paintings.

Materials, 2019

Here, a systematic study in order to assess the potential of THz time domain reflectometry for me... more Here, a systematic study in order to assess the potential of THz time domain reflectometry for measuring the thicknesses of overpaint layers applied on original gilded surfaces was carried out. The work is part of a thorough characterization campaign, which is going on at the Rijksmuseum for addressing the conservation problems of a set of 19th century gilded picture frames on which heavy coatings were applied in previous undocumented restoration interventions. To perform such non-invasive thickness measurements, an analytical protocol based on Gaussian fits of the THz pulse-echo temporal profiles was optimized through the preparation of suitable technical samples and the comparison with direct thickness measurements. Finally, the methodology was validated by characterizing the microstratigraphy of an original sculptural element from a gilded picture frame in the Rijksmuseum collection. The results achieved show the effectiveness of the present approach in revealing multi-layered di...

A THz Time Domain spectrometer was used to investigate painting layers in reflection geometry. Th... more A THz Time Domain spectrometer was used to investigate painting layers in reflection geometry. The stratified layers were characterized and the refractive indexes were measured. The results were used for estimating the thicknesses of superimposed paint layers.

Journal of Cultural Heritage, Jul 1, 2023

Zenodo (CERN European Organization for Nuclear Research), Nov 18, 2019

The present work is focused on the study of laser-induced effects that can occur in cadmium yello... more The present work is focused on the study of laser-induced effects that can occur in cadmium yellow paint films. To this aim, samples were prepared with different binders (linseed oil and polyvinylalcohol), mixing methods (manual vs. sonication) and pigment volume concentration (PVC). Laser experiments were performed under a microscope-based setup coupled to a spectrometer, which allowed to study surface and in-depth changes thanks to 2D image processing and 3D reconstructions. The present methodology revealed effective for studying the role that binder, particle-size and density distribution have upon laser irradiation. Results showed the threshold fluences strictly depend on the type of binder and PVC. The damage nucleation is size-dependent with fluence and PVC, and the microdamaged sites can be ascribed to non-linear absorption of CdS aggregates, whose size is of the order of the incident wavelength. These conclusions were further corroborated by Vis-NIR PL emission and reflection and ESEM-EDX.

Zenodo (CERN European Organization for Nuclear Research), Nov 15, 2019

مجلة مرکز المسکوکات الإسلامية - مصر

This work approaches the Islamic coinage as a rich resource for understanding the Islamic metallu... more This work approaches the Islamic coinage as a rich resource for understanding the Islamic metallurgy. Interdisciplinary scientific research of Islamic coin, using numismatic and multi-analytical studies, provided complementary data to overcome the limitations of the current numismatic research by conservators, curators, and scholars in the Arab region. The chemical analysis of the coin alloy using XRF, EDS, LIPS, and XRD showed the presence of silver-Copper alloy, and the corrosion products. Moreover, the use of Nd: YAG ns laser cleaning (1064 nm) for removal of the tarnish and corrosion layers for conservation and aesthetics purposes was assessed using scanning electron microscope couples Energy Dispersive X-Ray Spectrometer (SEM-EDS), Laser Induced Plasma Spectroscopy (LIPS), and X-ray Florescence spectrometer (XRF). The sensitive surface of the Islamic silver coin was treated safely using ns laser (1064nm) with fluences of 0.5-0.6 J/cm2 without inducing thermal side effects or chemical damage while a slight surface contrast loss was detected. Following the

Forests, Apr 18, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Journal of Cultural Heritage

JPhys photonics, May 15, 2024

Journal of Cultural Heritage, Feb 29, 2024

CRC Press eBooks, Oct 12, 2023

Journal of Cultural Heritage

Zenodo (CERN European Organization for Nuclear Research), Nov 18, 2019

CRC Press eBooks, Oct 12, 2023

Materials, 2019

Journal of Cultural Heritage, Jul 1, 2023

Zenodo (CERN European Organization for Nuclear Research), Nov 18, 2019

Zenodo (CERN European Organization for Nuclear Research), Nov 15, 2019

مجلة مرکز المسکوکات الإسلامية - مصر

Forests, Apr 18, 2023

Journal of Cultural Heritage

Applicazioni laser nel restauro 6, 2019

Abstract Before restoring ancient and valuable ethnographic objects many aspects should be taken ... more Abstract
Before restoring ancient and valuable ethnographic objects many aspects should be
taken into account, because lignocellulosic fibers-based materials undergo different
and concomitant degrading reactions (oxidation, hydrolysis, depolimerization) over
time. Basically, dry cleaning methods should be preferred, as they are potentially less
invasive in the long term, especially for the easily hydrolysable components. Here, the
fundamental and second harmonic of Q-Switch Nd:YAG laser, were comparatively investigated
for dealing with the removal of soiling (soot, dirt, aluminum silicates, carbonaceous
material) from a woven-fibers angarêb bed, which is preserved at Africa
Hall of the National Geographic Society Museum (Cairo, Egypt). Besides fiber identification,
laser induced-effects were assessed on angarêb fibers by means of stratigraphic
examination, Vis-NIR fluorescence emission, Raman spectroscopy, ESEM-EDX analysis
and optical microscopy observations.
Irradiation at 532 nm negatively affects color appearance and structural integrity
of fibers. Bond-breaking/depolymerization followed by bleaching, due to the significant
absorption of lignin/phenolic-carbohydrate and lignin-quinonoid complexes, occur at
this wavelength.
The promising results achieved at 1064 nm, in term of chemical and structural
integrity, highlight the possibility of using this wavelenghth for treating soiled and untreatable
ethnographic material.