Review of Samples from the 1994 CCI Workshop " Varnishes: Authenticity and Permanence " after 15 Years of Natural Ageing (original) (raw)
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Towards more stable natural resin varnishes for paintings
2003
Many of the new insights in the aging processes arose from the use of two analytical methods newly introduced in the field of conservation science: graphite-assisted laser desorption/ionization mass spectrometry (GALDI-MS) and electron paramagnetic resonance spectroscopy (EPR). These two analytical tools are presented in some detail in this Chapter. 2.1 Mass spectrometry Mass spectrometry is an analytical method that separates the components (analytes) of a sample by their molecular masses. To do so, the analytes are brought into the gas phase and ionized. Subsequently, the analytes are separated by their mass and detected. Thus, a mass spectrometer consists of three steps: 1. Ionization (analyte vaporization and ionization) 2. Mass separation 3. Ion detection There are many different ways to accomplish each step, and most of them can be combined according to requirements. However, only the few methods relevant for this thesis will be discussed here, matrix-assisted laser desorption...
Ge-conservacion, 2011
René de la Rie has been working since 20 years on Low Molecular Resins. In February, 2011 a technical Workshop took place, organized by GEIIC (Spanish group of International Institute of Conservation) in the Reina Sofia Museum. René de la Rie, Ana Ordoñez and Lourdes Domedel were the speakers and presented the results of the research they carried out. Questions that arose at this meeting are addressed in this interview.
2016
Historically, the varnishes had the aim to protect the bowed musical instruments by the external agents and to confer them an aesthetic value. During the 17 th and 18 th century, in Italy, the bowed instruments, especially violins, were generally covered by a layer of varnish made with several natural materials such resins, oil or hide glue: i.e., instruments by the great violin maker Antonio Stradivari were covered often with a layer of varnish made of linseed oil and colophony in the ratio 3:1, respectively. The main aim of this work was to study the modifications that occur in those kinds of varnishes, after exposing them to some factors of degradation. In order to study the different properties of organic coatings and their suitable compositions, different mixtures of linseed oil and colophony were recreated in the laboratory following an ancient recipe: linseed oil and colophony were mixed together with different ratios (50/50 and 75/25, respectively) and then, they were applie...
A Formulation for a New Environmentally Friendly Varnish for Paintings
MDPI Journals Coatings Volume 13 Issue 9 , 2023
Laropal® A81 is a urea-aldehyde resin used as a varnish for paintings requiring 30%–40% of aromatic solvents to be dissolved. Considering the dangers of aromatic solvents for the environment and health, an attempt was made to replace them with less impactful and low-toxic solvents. The present research investigates a new formulation with aliphatic hydrocarbons and esters (isobutyl isobutyrate, IBIB) as an alternative to traditional aromatics mixture. Traditional and alternative varnish formulations of Laropal® A81 were studied on an inert support and paint samples to test the resin by itself and in interaction with paint film, respectively. This study aims to compare the two different formulations of Laropal® A81 by evaluating their optical, colorimetric, and stability proprieties before and after natural and accelerated ageing. Colorimetry and spectroscopic techniques (transmittance and reflectance UV-VIS-NIR, FORS, transmittance and total reflectance FT-IR, and 1H-NMR) were used for the assessment. Very promising results have been obtained with the application of the alternative formulation, with data comparable to those of the traditional formulation, paving the way for the replacement of the aromatic-based solvents traditionally used with IBIB. This allows a safer and more sustainable conservation practice with considerable benefits for the health of the operators and the environment.
2016
The monitoring of performance characteristics of resins was always an issue for the conservation community, since the stability of the art objects depends on the service life of conservation materials used. Among the resins commonly applied in the field of paintings conservation, four of the most popular ones, Paraloid B72, Primal AC33 (acrylic polymers), Ketone Resin N (cyclohexanone) and Laropal A81 (urea-aldehyde) were selected to be comparatively studied under accelerated ageing conditions. These resins have been used by the art conservators either as consolidant materials of the paint or as protecting varnishes for the painting surface. The behaviour of the coatings under thermal ageing was investigated following a methodology depositing films of all materials onto different solid substrates (silicon wafers, quartz and simple glass slides) depending on the method of analysis used. Accelerated thermal ageing tests were conducted at 100 o C, for up to 432 hours. The morphological characteristics of the resins films (crack formations and surface alterations, coherence of film layers, thickness and surface roughness) were examined through scanning electron microscopy (SEM). Chemical changes of the resins were studied with FTIR and UV-Vis spectroscopy, while colour properties and thermal-chemical stability were also studied with spectro-colorimetry. It was found that, although all four displayed changes concerning their colour and film thickness, the two acrylic polymers and the aldehyde resin exhibit high stability against chemical degradation compared to the cyclohexanone based resin. Complementary solubility and swelling testing were also applied and significantly aided in supporting the spectroscopy observations. Finally, microscopic examination of most resin films revealed cracking features which may sometimes render them unsuitable for application under uncontrollable conditions.