Varnish

Aloe plants have been widely documented in artists’ treatises dating from the sixteenth to the nineteenth century as a source of colorant to achieve lustrous golden glazes on tin- and silver-foiled objects and warm-toned finishes on musical instruments, such as violins. Aloe extracts contain characteristic anthraquinone and phenolic components which impart a distinctive orange tone and fluorescence to mixtures containing them. Because of the low concentration of colorant in the coatings and its probable degradation by high temperature during manufacture, the identification of aloe in heated oil–resin mixtures represents an analytical challenge. For this reason, the possible presence of aloe in glazes and coatings has been largely overlooked. This paper describes various analytical approaches to the identification of aloe in historic samples, from comparison with results obtained from reference standards and mock-up samples. Complementary analytical techniques including thermally assisted hydrolysis and methylation–gas chromatography–mass spectrometry, high-performance liquid chromatography, laser desorption–mass spectrometry, matrix-assisted laser desorption-ionization-mass spectrometry and surface-enhanced Raman scattering were used. Different chemical markers were identified by the individual methods and the advantages and limitations of each technique for the identification of aloe in oil–resin varnishes are discussed.

The importation of natural resins, the advent of the manufacture and the dissemination of knowledge through printed
matter de󿬁ned the practice of varnishing in America in the second half of the 19th century. As the progress of industry allowed for
factory-based production of varnish, some methods of medieval origin that proved empirically durable and economically viable for
application to architecture scale remained relatively unchanged. An examination of some of the early manufactures helps to illumi-
nate the widespread use of the copal oil varnishes that are well documented to have been applied to interior woodwork during the
period. Several of the sources studied describe in great detail the preparation, aging, application and polishing of copal varnishes.
 Through an overview of documented materials and techniques, it becomes apparent that these combined practices affect impor-
tant functional properties of durability, clarity and luster in addition to other aesthetic attributes.

The historical varnish technology is of interest to various fields in cultural heritage. To understand the material properties of these historic surface coatings it is important to get insight in the technological background, i.e. the relationship between the material and the processing method. This study has specifically focused on the use of pumice stone and bone ash often mentioned in historical sources as driers for oil-based coating systems. For this purpose lute and Italian violins from the period between the 16 th to the mid 18 th century were examined. Both, the main organic composition of the varnish and the addition of mineral additives were considered. Based on the analytical data and the corresponding information from historical written sources, the siccativation of oil-based varnishes with pumice stone and bone ash was simulated experimentally. The results of these reconstructions confirm that the technological know-how behind these varnishes is far more complex than it may appear at first glance and that the organic and inorganic components must be regarded as a balanced technological system where each of the various components has a specific function. In this context, these inorganic additives effectively induced accelerated drying, improved the mechanical film properties of young films and showed a stabilizing effect on the long-term degradation during aging.

Veil of Death. Overlaying and Distancing Patterns in Monet’s Camille on her Death Bed. Camille Monet on her Death Bed painted by Claude Monet in 1879 is a post mortem portrait of the impressionist’s first wife and longtime model, Camille Doncieux. This picture raises many questions concerning its function as a funeral portrait and as an artistic experimentation on the medium of painting. One of the very few documents mentioning this work is a quote by Georges Clemenceau reporting that Monet told him many years after its execution, that when realizing this “last portrait” he could not avoid being mesmerized by colors and painterly surfaces that his painter’s gaze was generating even when confronted to the body of a beloved one. This citation evokes several topoï related to the modern artist used by Honoré de Balzac in his Unknown Masterpiece, by Emile Zola’s Work or transcribed in statements attributed to Paul Cézanne. The numerous veil and surface effects question the status of this image and highlight Monet’s explorations of the pictorial surface during this period. The veiling, distancing and deindividualizing strategies used
in Camille Monet on her Death Bed are closely analyzed and compared with similar patterns appearing in Georges Seurat’s Anaïs Faivre Haumonté on her Death Bed or AndyWarhol’s
screenprints.

Varnishes greatly influence the appearance of paintings as well as any other field of  fine arts.
The varnish layer is one of the most critical parts of a work of art since it essentially participates in the visual effect of the work-covering layers which constitute representation.
The Rome Conference of 1930 defined the first guidelines for varnish interventions and re-varnish requirements for works of art, fully conscious of the fact that the perfect varnish did not exist. Extensive research followed and pursued the replacement of natural materials with  more stable synthetic ones. In the course of time the principles  of varnishing has changed as the consequence of the Rome Conference recommendations. Today, conservators-restorers very seldom deal with original (historic) varnishes, since the normative treatment after Rome included their removal and re-varnishing with modern, clear substances.
The  generation of great researchers, such as Robert L. Feller, René de la Rie and their associates, have dealt with qualitative changes of the varnish layer. Despite extensive research into picture varnishes and their solvents, little information is available on their expedience and protection efficacy.
Varnish is the interface between a work of art and its immediate environment. At the same time it is a filter for the oxidation and light degradation processes, which would otherwise  affect directly the paint layer. An important requirement therefore is to upgrade the ability of the varnish screen to protect the paint layer.
From the restoration standpoint, the protection of the paint layer is a matter of the utmost importance since the paint layer carries the aesthetic integrity of and vital information on the work of art.

Title of the thesis:  Aesthetic presentation of painting Marija dobrega srca by the painter Anton Cebej from the Franciscan Friary in Kamnik

        The graduation thesis is about the conservation and restoration of the late Baroque painting Marija dobrega srca by the painter Anton Cebej from the Franciscan Friary in Kamnik. The painting is currently located at the National Gallery in Ljubljana due to restoration before an announced exhibition. In this paper I shall describe the treatments of conservation and restoration which I have performed on the painting Marija dobrega srca.
        In the first part of the thesis I shall deal with the general characteristics of the time the painting originates from through historical and theological aspects. The iconography of the painting on canvas is described. Before the realization of the conservational-restorative intervention I shall tackle aesthetic development within the field and the debates of experts on the approach to conservation and restoration of works of art.
        Concretization is achieved in the fourth segment which refers to the classical conservational approach with an emphasis on reports on the treatments. Further treatments will be thoroughly described with diagnosing the original state and the realization of all of my interventions performed on the painting Marija dobrega srca.

The reflectance factor of a diffuse plane background covered by a non-diffuse but partly absorbing layer is computed as a function of the incident and observer angles, and of the background reflectance factor. The particular case of back-scattering configuration is then studied. Numerical simulations are presented and discussed for a lambertian background and a transparent layer. Measurements with a gonio-spectrophotometer

Allied government intelligence agencies working in Germany during the closing chapters of the Second World War, and immediately after the cessation of hostilities, invited various interested official bodies and businesses to join them in collecting commercial information. Among many industries, artists' colourmen wholeheartedly took up the baton of the state-sponsored sequestration of German intellectual property relating to pigments, binders, canvas, inks and other materials. Representatives of Winsor & Newton Ltd. and George Rowney & Company spent nearly a month in Germany attempting to gain knowledge of German products and processes in order to improve their own. At the same time, efforts to profit from the empirical knowledge of a German academic expert was made by some of the most august art institutions in London, such as the National Gallery and the Courtauld Institute of Art, by exploiting state mechanisms for the forcible removal of some of these individuals from German to British soil. Significant roles were played by this individual in the criminal organisations of the National Socialist genocidal and totalitarian regime, but these British institutions extended every effort to benefit from the accrual of his professional knowledge in respect of materials, conservation and teaching expertise.

The purpose of this 1994 workshop was to introduce participants to traditional and modern varnishes and to compare their characteristics and handling properties. Twelve test panels from the workshop were brought to the Centre de conservation du Québec (CCQ) in Quebec City and mounted on a wall in the paintings lab, where they were left to age for fifteen years. Visual comparisons were made to evaluate differences in colour change and gloss. It was concluded that adding Tinuvin 292 to mastic and dammar varnishes to inhibit premature yellowing (in the absence of UV light) is very important since all unstabilized varnishes made with these resins discoloured to some degree. Most proprietary varnishes showed no discoloration. However, those based on ketone resins gave less consistent results. It was particularly encouraging to see how well the Regalrez 1094 samples have aged. Their superior performance with regard to yellowing (with or without the addition of Tinuvin 292) and their rapid solubility in isooctane after 15 years of natural ageing may make Regalrez a suitable varnish for acrylic paintings. Surprisingly, four different unstabilized varnishes based on copal-oil formulations show only a trace of discoloration. It remains to be determined how these varnishes would age in environments where UV light is not filtered. Cet article fait un constat sur le vieillissement naturel d'échantillons de vernis appliqués sur des panneaux peints, créés lors de l'atelier de l'ICC en 1994. Le but de l'atelier était de faire connaître aux participants des vernis traditionnels et modernes et de les comparer. Un jeu de douze panneaux a été exposé pendant quinze ans sous les conditions ambiantes de l'atelier des peintures au Centre de conservation du Québec. Les observations présentées sont des évaluations comparatives faites par des restaurateurs. En conclusion, lors de l'emploi du mastic ou du dammar, il est essentiel d'ajouter un stabilisant, comme le Tinuvin 292, afin d'empêcher le jaunissement prématuré de ces vernis (en l'absence de rayons ultraviolets). Ces mêmes résines non stabilisées ont toutes jauni. Il est rassurant de constater que la plupart des vernis synthétiques testés n'ont pas jauni. En contrepartie, la qualité du vieillissement de vernis à base de résine cétone demeure incertaine. Le Regalrez 1094 a donné un très bon rendement, sans ou avec l'ajout de Tinuvin 292. Sa solubilité rapide dans des hydrocarbures, tels que l'isooctane, faciliterait son application ainsi que son retrait éventuel des peintures acryliques. Quatre vernis différents à base d'huile-copal (non stabilisés) ne démontrent qu'un soupçon de jaunissement. Il reste à savoir quel type de vieillissement auraient présenté tous ces vernis sous une quantité appréciable de lumière ultraviolette.

In this study, the long-term (5-year) performances of 2 varnish systems, semitransparent alkyd-based brown stain (SABBS) and alkyd-based clear varnish (ABCV), were evaluated on preservative-treated Scots pine (Pinus sylvestris L.) sapwood. Prior to varnish application, specimens were impregnated with 2 different types of wood preservative. The experimental variables were varnish type, layer thickness, and wood preservative. ASTM D 1641 was followed for exposing wood specimens to outdoor conditions. The effects of long-term exposure on adhesion properties of applied varnish systems were tested according to ASTM D 4541. Long-term outdoor exposure resulted in 4.2% and 33.9% reductions in the adhesion properties of SABBS and ABCV varnish systems, respectively. The layer thickness and preservative type did not show any statistical reductions in adhesion properties.

Tevvy Ball, Managing Editor Sylvia Tidwell, Copy Editor Anita Keys, Production Coordinator Hespenheide Design, Designer Printed in the United States of America 10 987654321 © 1999 by the J. Paul Getty Trust All rights reserved. Illustration credits: Figures 3.8, 4.27, 4.28, 4.29, 5.16, 5.24, ...

During the conservation of the painting La probatica piscina
by Giovan Battista Paggi, a glue film was found, applied in
a previous restoration work to improve the application of
final varnish. When a varnish is applied, it will often ‘sink-in’
to the absorbent areas while lying on top of the non-absorbent
areas resulting in an uneven surface. From Ulisse
Forni’s method to Mario Modestini varnish technique and
Gustav Berger’s applicative researches many isolating
varnishes were suggested to solve the case on surfaces
that were difficult to saturate, without considering the
potential interaction with the original paint. A short
illustration of the different methods and materials of the
isolating varnishes is followed by the relative evaluations
and the painting conservation results, in the hope of future
scientific studies on this particular topic.

La triéthanolamine est l’un des ingrédients principaux des savons résiniques et biliaires. Elle présente un mauvais vieillissement (jaunissement) ainsi qu’une affinité avec la couche huileuse des peintures, laissant des résidus après utilisation. Il est donc intéressant de comprendre comment fonctionnent ces savons de façon à remplacer cet ingrédient problématique par des substituts facilement accessibles aux restaurateurs.

Le travail présenté dans cet article a été réalisé par l’auteur lors de son Master 2 en conservation et restauration de peintures à la Cambre. Une brève introduction des savons sera faite, puis leurs principales utilisations, ainsi que leur composition et fonctionnement seront expliqués. Ensuite, la polémique autour de ces produits sera résumée et permettra d’introduire la partie pratique, dans laquelle les nombreux essais réalisés dans le but de remplacer l’un des ingrédients principaux du savon supposé problématique seront présentés.

In the present work, a study attempting to characterize the Manila elemi and Mexican copal resins from the Burseraceae family, which are used as components of varnishes and binding media of artworks, has been carried out. A new GC–MS method involving the use of methyl chloroformate as derivatisation reagent has been proposed. A second method which uses pyrolysis-GC–MS and hexamethyldisilazane

Thermooxidation at 100°C and photooxidation at wavelengths above 300 nm of dried oil films were evaluated. The chemical modifications of the networks were determined by infrared analysis coupled with gaseous treatments (NO, SF4, and NH3). The dried films are rather stable in thermooxidation, whereas in photooxidation, important degradation of the network occurs with many chain scissions. This photoinstability results from the presence of crosslinks that are sensitive to radical attack because of the lability of the hydrogen atom on the tertiary carbons. The photooxidation reactions are fully described in this paper. Yellowing of the cured samples, observed with ultraviolet-visible and fluorescence spectrometries, rapidly is decreased by irradiation because the oil contaminants that are mainly responsible for the yellowness are photooxidized. On the contrary, yellowing slowly but continuously increases during thermooxidation at 100°C.

Infrared spectroscopy (FTIR) is a standard technique for the characterisation of organic materials in conservation science. This analytical technique is particularly interesting to analyse historical varnishes from cultural artefacts, as only minute samples are required. Some limitations apply, however, when analysing such chemically complex multi-component materials with interfering absorption bands. A previously introduced sample pre-treatment method using gaseous sulfur tetrafluoride SF4 has shown to widen the application fields of the IR-technique by improving its specificity. One of these new fields is its successful application to the characterisation of complex aged natural varnish and lacquer systems. The fluorination treatment leads to characteristic band shifts of four individual saturated and unsaturated acid groups attached at varying positions of the terpene backbone. This allows the separation of otherwise overlapping carbonyl bands of different ketones and ester groups. Based on this technique, inert and unique functional groups can be used as material specific markers to identify drying oil, shellac and different terpene resins in varnishes and lacquers. The proposed markers proved to be stable for several hundred years. These findings are particularly interesting, as it is now possible to trace such markers even in very old varnishes dating back to the 16th century – with a likewise simple technique.

The application of varnishes on the surface of metal objects has been a very common practice since antiquity, both for protective and aesthetic purposes. One specific case concerns the use of tinted varnishes on copper alloys in order to mimic gilding. This practice, especially flourishing in the 19th century for scientific instruments, decorative objects, and liturgical items, results in large museum collections of varnished copper alloys that need to be preserved. One of the main challenges for conservators and restorers deals with the identification of the varnishes through non-invasive and affordable analytical techniques. We hereby present the experimental methodology developed in the framework of the LacCA and VERILOR projects at the Haute École ARC of Neuchâtel for the identification of gold varnishes on brass. After extensive documentary research and analytical campaigns on varnished museum objects, various historic shellac-based varnishes were created and applied by differe...

... Une dizaine d'especes se trouve au Moyen Orient (Asensi Amoros, comm. ... Mes remerciements vont aussi à Mme Victoria Asensi Amorôs, égyptologue/xylologue attachée au Laboratoire de Paléobotanique et Paléoécologie de l'Université Pierre et Marie Curie et à l'Université d ...

La réflexion sur le remplacement du traditionnel vernis à
la gomme-laque par une autre couche de finition a débuté en 2002
au C2RMF. Elle avait pour but de mettre en évidence les éventuelles
relations entre dégradation et composition du vernis, d’évaluer le
rôle de protection sur les bois de vernis de compositions différentes
et enfin d’étudier l’influence de la lumière sur l’évolution dans le
temps des bois ainsi vernis. L’expérimentation mise en oeuvre s’est
focalisée sur un vernis décrit dans L’Art du menuisier-ébéniste
publié par André-Jacob Roubo en 1774. Plusieurs tests de mesure
d’épaisseur, d’apparence et de propriété mécanique ont été réalisés
sur des éprouvettes de bois de placage recouverts du vernis
sélectionné. Les résultats encourageants de son effet protecteur à la
photo-oxydation et à l’oxygène de l’air ont permis de mettre en place
un protocole en vue de son application comme protection de surface
pour le mobilier en marqueterie de métal du musée du Louvre.
Reflection on replacing traditional shellac varnishes
with another finish began in 2002 at the C2RMF. The aim was to
highlight the possible relationship between deterioration and the
composition of the varnish, to assess the role played by protective
coatings made of different ingredients on wood and, lastly, to study
the long-term effects of light on woods thus varnished. The
experiments conducted focused on a varnish described in L’Art du
menuisier-ébéniste, published by André-Jacob Roubo in 1774.
Several tests to measure thickness, appearance and mechanical
properties were carried out on samples of veneer coated in the
selected varnish. The encouraging results of its resistance to photooxidation
and the oxygen in the air enabled us to establish a
protocol for applying it to protect the surface of the metal marquetry
furniture now in the Louvre.

--> https://www.kb.nl/amsterdam-rijksmuseum-0

Het Rijksmuseum bezit een omvangrijke collectie oude boeken die afkomstig zijn van verschillende afdelingen (Rijksprentenkabinet, Geschiedenis, Beeldende Kunst, en de Research Library) en het Koninklijk Oudheidkundig Genootschap. Kunstenaarshandleidingen, zoals receptuurboeken en voorbeeldboeken voor kunstenaars en liefhebbers, worden actief verzameld en vormen een belangrijk onderdeel van de collectie.
Een aanzienlijk deel van deze boeken werd in Nederland of in de Nederlandse taal gedrukt – een gegeven dat de collectie uitermate interessant maakt voor de Short Title Catalogue Netherlands (STCN). In 2015 werd daarom begonnen met het beschrijven van de 5148 Nederlandse titels van vóór 1800 uit de collectie van het Rijksmuseum in deze retrospectieve nationale bibliografie van Nederland. 822 titels, edities of titeluitgaven werden daarbij niet eerder aangetroffen bij een andere deelnemende instelling. De aanzienlijke hoeveelheid ‘unica’ en het specifieke karakter van de titels gaven de aanleiding voor deze webexpositie die bovendien de afronding van de STCN-werkzaamheden in het Rijksmuseum viert.
Er is gekozen voor een eenheid van acht titels uit de collectie historische kunstenaarshandleidingen die het afgelopen jaar voor het eerst werden opgenomen in het STCN-bestand. Uiteenlopende aspecten van de vroegmoderne kunstliteratuur worden voor het voetlicht gebracht: van de herkomst van de moffellak en de ateliergeheimen van J.F. Lindenbergh tot het doen en laten van Hollandse knipkunstenaars.

Teksten door Lisa Wiersma (kunsthistorica, Universiteit Utrecht) en Daphne Wouts (kunst- en boekhistorica, Universiteit Leiden/STCN).

El estudio muestra en qué grado dos técnicas pictóricas, acuarela y pigmentos aglutinados al barniz (Gamblin), utilizadas en la reintegración cromática de obras arte, experimentan un cambio de color tras ser barnizadas. El método de trabajo ha consistido en aplicar dos tipos de barniz, mate y brillante, sobre diferentes muestras de color de cada una de las dos técnicas pictóricas analizadas. El análisis colorimétrico realizado sobre las muestras barnizadas y el estudio comparativo de los resultados obtenidos permiten conocer hasta qué punto se produce un cambio de color sobre cada una de ellas y qué parámetro claridad, croma o tono es el que tiene mayor influencia en el cambio.

This study was performed to determine the impact of impregnation with boron compounds on the surface hardness of varnished wood materials. For this purpose, test specimens prepared from Oriental beech (Fagus orientalis Lipsky) and oak (Quercus petreae Lipsky), which met the requirements of ASTM D 358, were impregnated according to ASTM D 1413 with boric acid and borax by a vacuum technique. After impregnation, the surfaces were coated by cellulosic, synthetic, polyurethane, waterborne, acrylic, and acid hardening varnishes in accordance with ASTM D 3023. The surface hardness of the specimens after the varnishing process was determined in accordance with ASTM D 4366. According to the wood type, impregnation material, and varnish type, the surface hardness was highest for the oak impregnated with borax and acrylic varnish and lowest for the oak impregnated with borax and synthetic varnish. Therefore, impregnation with boron compounds showed an increasing impact on the surface hardness of the varnished wood. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

For the last 60years, varnishes of ancient musical instruments, particularly stringed instruments of the violin family dating 17th and 18th centuries, have been analysed to establish their chemical composition and multi-layered structure. The objective was to rediscover the technology for making the varnish of esteemed Italian violins and to reconstitute it. This paper reviews the physico-chemical studies published on such varnishes and also focuses on a research project carried out since 2002 at the Musée de la musique in Paris. It aims to apply in a comprehensive way different non-destructive or micro destructive methods (Py-GC/MS, IR microscopy, SEM/EDX, EDXRF, synchrotron radiation-based techniques, …) to the study of a large and representative number of ancient varnished musical instruments from a museum collection.

Two violins were investigated. The only intentionally introduced difference between them was the type of varnish. One of the instruments was covered with a spirit varnish, the other was oil varnished. Experimental modal analysis was done for unvarnished/varnished violins and a questionnaire inquiry on the instrument’s sound quality was performed. The aim of both examinations was to find differences and similarities between the two instruments in the objective (modal parameters) and subjective domain (subjective evaluation of sound quality). In the modal analysis, three strongly radiating signature modes were taken into account. Varnishing did not change the sequence of mode shapes. Modal frequencies A0 and B(1+) were not changed by oil varnishing compared to the unvarnished condition. For the oil varnished instrument, the frequency of mode B(1+) was lower than that of the same mode of the spirit varnished instrument. Our two violins were not excellent instruments, but before varnish...

The curing of drying oils at 60°C has been investigated by Fourier transform infrared spectroscopy and Fourier transform Raman analysis of linseed oil and poppyseed oil. In the first step, hydroperoxides are formed (broad vibration band centered around 3425 cm−1) with concomitant conjugation and cis-trans isomerization of the double bonds (disappearance of cis bands at 3011 and 716 cm−1, appearance of trans conjugated and trans nonconjugated bands at 987 and 970 cm−1). The subsequent decomposition of hydroperoxides in the presence of oxygen leads to the formation of alcohols (nitrite band at 779 cm−1 after nitrogen monoxide treatment), aldehydes (bands at 2810 and 2717 cm−1 in gas phase), ketones (saturated and unsaturated at 1720 and 1698 cm−1, respectively), carboxylic acids (saturated and unsaturated acid fluorides identified at 1843 and 1810 cm−1 after SF4 treatment), and peresters or γ-lactones (near 1770 cm−1). A rapid decrease in the double-bond concentration is recorded when curing continues, and the formation of epoxides, characterized by a vibration band at 885 cm−1, is observed. Thermolysis experiments have suggested the proposal of a reaction of addition of peroxyl radicals on the conjugated double bonds as a probable mechanism. This mechanism explains both the rapid disappearance of conjugated double bonds and the formation of epoxides as intermediate products observed in the initial step of curing.

Keeping agents that cause biodeterioration under control is a common task in restoring and conserving artworks. However, there are very few studies, specifically those concentrating on pictorial works, that provide solutions compatible with the complex mix of organic and inorganic materials to be found in such cultural assets. This study aims to use biocide products that are commonly used in this field (benzalkonium chloride, o-phenylphenol, and tributyltin naphthenate) and which are associated with natural varnishes with a long tradition in artistic practices, in order to protect paintings and polychrome sculptures from environmental fungi and bacteria without altering the original materials or the visual appearance of the artworks. The effectiveness or innocuousness of the treatments was tested chemically and visually via optical microscopy, gas chromatography–mass spectrometry (GC-MS), and a multidimensional scaling analysis (MDS); the treatments produced good results as regards ...

The Department of Art Conservation at the University of Delaware is honored to participate in this online initiative which now includes educational resources in addition to an interactive forum that will provide independent information on art materials. It is hoped that the site will serve as a guide for artists who are interested in learning about best practices as well as up-to-date scientific research on contemporary art materials and artistic techniques. The absolute objectivity of the forum makes it especially valuable. Specific brands and products may be mentioned on the site and forum relating to questions, however, no specific brands will be promoted.  Any brands mentioned in the site’s resources are meant to serve as comparative examples. MITRA will discuss general conservation topics such as guidance about contacting trained professionals and general tips regarding exhibition, storage, transportation, and handling, but will not recommend or describe restoration materials or techniques.  The forum is first and foremost dedicated to providing the most comprehensive, up-to-date, accurate, and unbiased information about artists’ materials.