Removal of a Past Varnish Treatment from a 19th-Century Belgian Wall Painting by Means of a Solvent-Loaded Double Network Hydrogel

Polymeric materials have been used by painting conservator-restorers as consolidants and/or varnishes for wall paintings. The application of these materials is carried out when confronting loose paint layers or as a protective coating. However, these materials deteriorate and cause physiochemical alterations to the treated surface. In the past, the monumental neo-gothic wall painting ‘The Last Judgment’ in the chapel of Sint-Jan Berchmanscollege in Antwerp, Belgium was treated with a synthetic polymeric material. This varnish deteriorated significantly and turned brown, obscuring the paint layers. Given also that the varnish was applied to some parts of the wall painting and did not cover the entire surface, it was necessary to remove it in order to restore the original appearance of the wall painting. Previous attempts carried out by conservator-restorers made use of traditional cleaning methods, which led to damage of the fragile paint layers. Therefore, gel cleaning was proposed as a less invasive and more controllable method for gently softening and removing the varnish. The work started by identifying the paint stratigraphy and the deteriorated varnish via optical microscopy (OM), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. A polyvinyl alcohol–borax/agarose (PVA–B/AG) hydrogel loaded with a number of solvents/solvent mixtures was employed in a series of tests to select the most suitable hydrogel composite. By means of the hydrogel composite loaded with 10% propylene carbonate, it was possible to safely remove the brown varnish layer. The results were verified by visual examinations (under visible light ‘VIS’ and ultraviolet light ‘UV’) as well as OM and FTIR spectroscopy.

Restaurarea unei picturi pe pânză de Aurél Náray (1883–1948)

"The restoration of a painted canvas by Aurél Náray (1883-1948) This study shows the restoration work made on the painted canvas of the Hungarian artist Aurél Náray (1883-1948), depicting an ecclesiastic subject (Saint Joseph with the infant Jesus). This oil painting comes from a private art collector and has the following dimensions: 42x57.5 cm, being sustained by a wooden stretcher. The painting is signed and dated by the artist himself on the lower left corner (“Aurél Náray 909”). The canvas is fixed on the underframe with metallic nails; as a result of the wood having dried, the frame shows slight distortions. The face of the painting displays small portions of missing white primer and/ or colour, erosions of the paint layer, two little punctures in the canvas, and a small area of distorted canvas placed toward the lower edge of the painting. Adherence of thin dirt can be observed on the surface of the painting while the back of the canvas bears heavy traces of dust and dirt, especially on its margins. The actual restoration process of the painted canvas referred to the following: drawing up the initial photograhic documentation, superficial dust cleaning on the back of the canvas, detachment of the painting from its old underframe and the building of a new and proper wooden stretcher. After the plainness of the painting was restored and the two small pricked points on the canvas were consolidated (with the use of Beva 371 adhesive), a strip lining on the margins of the canvas was carried out, in order to be able to fix the canvas on the new underframe. Cleaning of the surface came next, followed by the filling of the missing primer layer with putty. The chromatic integration of the painting was accomplished (after having sealed the original paint with a thin layer of intermediary varnish) with the use of low oil content colours and the final protection of a second satin varnish layer. Keywords: painted canvas, restoration, stretcher, strip lining, varnish "

Measurements of surface free energy as a tool to asses the effect of varnishing and printing of the paper substrates

Nowadays, printing products might be finished in various ways. Varnishing process is one of the most popular finishing method which gives various effect, such as mate, glossy etc. However, the varnish layer applied on the paper is very thin, therefore it can be invisible to the naked human eye. The aim of this work was to use contact angle measurement and surface free energy determination as a tool to assess the effect of printing and varnishing process of paper materials. We have used various tools in order to analyses the changes of surface: surface roughness, gloss, water contact angle absorption and surface free energy determination. Those tools were used in order to confirm whether the print has been covered with varnish or not. In this work six various paper substrates were used (glossy, coated and un-coated papers). The printing and varnishing was performed in laboratory conditions using flexographic water-based printing and waterbased varnish. Samples were prepared as follows: paper with ink coating, paper with varnish coating and paper with ink layer and varnish layer on the top. The surface roughness was determinated of all samples and compared. The surface roughness changes were observed for pure paper, overprinted and overvarnished. Next, the gloss of samples prior and after printing and varnishing was measured. The gloss of the samples increases when they are printed or varnished, what is related with properties of ink and varnish. Also, the thickness of ink and varnish layers was determinated. The thickness of the samples increases when the number of layers increases. Finally, the water contact angle was measured and surface free energy was calculated with Owens-Wendt method. Our results reveal the possibility of using various tools in order to confirm the performance of varnishing of the prints. The printing with various colors is always seen by the naked human eye. On the other hand, the varnish layer might be not visible. However, such a comparison is not possible if we do not have the pure paper substrates prior printing or varnish.

Comparative Effects of CPP-ACP and Xylitol F-Varnishes on the Reduction of Tooth Erosion and Its Progression

Evaluated the effect of CPP-ACP/NaF and xylitol/NaF varnishes in reduce erosion and progression of erosion. Forty enamel blocks were divided into four groups (n=10): G1=CPP-ACP/NaF varnish (MI varnishTM); G2=xylitol/NaF varnish (Profluorid®); G3=NaF varnish (Duraphat®, positive control) and G4=deionized water (MilliQ®, negative control). Samples were immersed in Sprite ZeroTM (pH 2.58, 4x/day, 3 days), in between immersions, the specimens stayed in artificial saliva. After 3 days of erosion, the eroded area was divided in two (half of one received an additional varnish layer while the other half repeated the same 3-day erosion cycle). The 3D, non-contact profilometry technique was used to determinate tooth structure loss (TSL) and surface roughness (SR). Scanning electron microscopy (SEM) and 3D images were utilized to evaluate the topography of the samples. Mann-Whitney, one-way ANOVA and Tukey tests were used (significance level of 0.05%). SEM and 3D images were descriptively evaluated. After 3 or 6 days of erosion, all tested varnishes were better than G4 (p<0.05) for TSL and SR. In addition, G1 had lower values for TSL than G3 (p<0.05) after 3 days of erosion. Under SEM and 3D images observation, all groups presented porosity, irregularities and depressions on the surface enamel after 3 and 6 days of erosion, more pronounced in G4. An application of topical NaF varnishes was effective in reducing TSL and enamel roughness after erosion challenges, being the CCP-ACP/NaF varnish more effective than NaF varnish and water after 3 days of erosion.

Real-Time Wood Behaviour: The Use of Strain Gauges for Preventive Conservation Applications

Within the heritage field, the application of strain gauges on wood surfaces is a little-explored but inexpensive and effective method to analyse the environmental appropriateness of rooms for the wooden heritage collections they contain. This contribution proposes a wood sensor connected to a data logger to identify short moments with an elevated risk of harm. Two experiments were performed to obtain insights pertaining to the applicability of wood sensors to evaluate preservation conditions. (1) The representativeness of strain gauges on dummies was tested for their use in evaluating the preservation conditions of a range of wooden objects exposed to the same environment. For this, three situations were mimicked: a bare wood surface, a wood surface covered with a preparation layer, and a wood surface covered with a preparation and varnish layer. (2) The usability of strain gauges to monitor the wood behaviour in real-time measurements was tested with a monitoring campaign of almost two years in a church where a new heating system was installed. The results of both experiments are promising, and the authors encourage a broader application of strain gauges in the heritage field.

Analytical and computational study of three coptic icons in Saint Mercurius Monastery, Egypt

Three wooden Coptic icons located at Saint Mercurius Monastery in Tamooh, Giza, Egypt were comprehensively investigated in order to determine the possible causes of their deterioration. Samples from every paint used in each icon were collected spanning from the outermost varnish layer down to the ground layer. Investigation was carried out using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Energy-dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF). For interaction between the icon layers DFT calculations at B3LYP/6-31g(d,p) level were conducted in order to study the effect of humidity on the reactivity of the binder material and its possible role in the deterioration of the icons.

Effect of Phosphoric Containing and Varnish-Coated Groups on Candida Albicans Adhesion and Porosity of Heat Cure Acrylic Denture Base Material

The aim of this study was to evaluate the effect of modified heat cured polymethyl methacrylate denture base (PMMA) or varnish coating of the denture base on candida albicans adhesion and porosity. First experimental group was prepared by addition of 15% phosphoric acid 2-hydroxyethyl methacrylate ester with polymethyl methacrylate monomer. While second experimental group prepared by varnish layer coating after material processing, these groups were compared with the control one. Three groups of vertex acrylic resin used as control, mPMMA and varnish coated group (PPH Cerkamed Wojciech Pawlowski, Poland). The inverted light microscope was used to measure the candida albicans adherence after one week and one month of processing. Two-way ANOVA, LSD test, T- test and Dunnett T3 were performed on data. Modified Acrylic resin showed highly significant reduction in candida albicans adhesion and porosity, also for varnish coating group showed highly significant reduction in candida albicans adhesion and porosity test.

Restaurarea picturii Peisaj cu biserică, de Ștefan Popescu

The paper presents some important aspects of the restoration- conservation process of a painted canvas, belonging to Ştefan Popescu, a romanian painter, whose creation, at the beginning of the 20th century, was famous especially through its landscapes. Stylistic and technological aspects of the painting were analyzed. The painting depicts a realistic landscape, with a house and an imposing stone church. A detailed account of the conservation state of the painting prior the restoration was made. The actual restoration process started with the cleaning of the superficial dirt and dust from the back of the painting. After protecting the entire face of the painting (by applying the Japanese paper), the old patch on the back of the painting (covering a small area of torn canvas) was replaced with a new one. The cleaning process (the removal of the light dirt and the old varnish layer) was followed by the filling of all the gaps of the painted layer with putty. The chromatic integration and the final varnishing ended the restoration process of the painted canvas.