CTS - FOCUS Archivio

CTS FOCUS

Archive of Past Issues of CTS Focus

Cold Plasma Against Viruses - In response to the pandemic, efforts have been made to enhance environmental sanitation. Methods like HEPA filters, UV radiation, and ozone have limitations and health and art risks. Cold plasma emerges as a safe alternative capable of inactivating viruses without harming cultural assets. Devices like Q3 and Q7 offer effective sanitation with low maintenance and no harmful ozone emissions, suitable for workspaces and museums.

An Injection of Stability - The new INJECTO VE PRO cartridges based on vinyl ester resin complement epoxy resins for fastening in construction. They are suitable for damp materials, low temperatures, and ensure rapid hardening. They offer user-friendly application with external mixing and visual control of homogeneity. They are ideal for securing fiberglass and steel bars with high mechanical strength and chemical stability, without releasing harmful vapors like polyesters.

Reswax WH wax was chosen for the protection of the bronzes at the Redipuglia sanctuary on the occasion of the centenary of the Great War. This product, effective since 1991, combines acrylic resin, wax, and benzotriazole as a corrosion inhibitor. The bronze plaques at the sanctuary, created in the 1930s, had been covered with gray synthetic paints to counter oxidation. The restoration included the removal of these paints and the patination with ammonium sulfide. After various tests conducted by the CNR and the University of Florence, CTS WH was chosen as the final protective coating due to its proven effectiveness in accelerated aging conditions and marine environments. The wax, enriched with super-ventilated graphite, provides an ideal tone and long-lasting protection against atmospheric and chemical agents.

The cosmetic industry, always in search of safe and effective materials, has evolved the use of pigments. From historic toxic berries to modern mica pigments, the latter offer stability, resistance, and safety. Mica pigments, used in various binders, create pearlescent, iridescent, and interference effects. They are non-toxic, heat-resistant, acid-resistant, alkali-resistant, and UV-resistant, making them ideal for cosmetics. Their semi-transparency allows for unique chromatic effects influenced by the base color.

Cellulose fibers, used in restoration and conservation, now have a new variant: Micro C8. This microcellulose, with fibers measuring only 8 µm in length, surpasses previous versions in fineness. With over 99.5% cellulose content, it's ideal for filling in paintings, statues, and paper artifacts, whether used alone or with other fillers. Compatible with various binders, Micro C8 enhances the workability of mixtures by being finer and more absorbent. Its neutral pH and density of 200 g/l make it versatile for various applications.

C.T.S. srl's new EVA FILM 65 is a 65-micron dry film adhesive, ideal for lining canvas paintings and other solvent-free applications. Composed of ethylene-vinyl acetate resins, urea-aldehyde, and microcrystalline wax, it is resistant to yellowing and reversible with polar solvents or heat. It replaces the ketonic resin Laropal K80, preventing yellowing. The adhesive is extruded onto a support film and covered with a protective film, creating a transparent sandwich for easy use. It is activated by heat and pressure or solvents and can be reactivated at 65°C or with solvents and heat. It is important to avoid temperatures above 70°C to prevent damage to the material. EVA FILM 65, available in a height of 1 meter, can be joined for larger dimensions and removed with various solvents or heating.

Nanotechnologies in restoration have led to innovations like Nanorestore and Nano Estel, but without hydrophobic effects. Recently, functionalized nanosilicas offer hydrophobic and oleophobic properties. Nanosilicas, silicon dioxide particles ranging from 5-100 nm, vary in type and properties. They react with the hydroxyl groups on stone surfaces, forming silica polymers. A recent study compared four functionalized nanosilicas with the siloxane Silo 112 on sandstone and limestone. After 4 months outdoors, some products maintained their protective effectiveness, while others did not. Product 4, now Nano Silo W, showed the best results in terms of minimal water absorption and color variations. Further tests are underway to assess its effectiveness on other stones and resistance to salt crystallization cycles. Products with oleophobic properties are also being explored for stain and graffiti protection.

Damar, an oriental resin introduced in the 19th century, was used as a painting varnish alongside mastic. Sourced from Dipterocarps in Indonesia-Malaysia-Siam, it varies in composition, containing resin acids, resins, and waxes. It tends to yellow under light but can be stabilized with Tinuvin 292 or covered with more stable varnishes like Regal Varnish. The new Regal Dammar Varnish on the market utilizes high-quality dammar with specific solvents, sensitive to climate changes. Its introduction recognizes the value of tradition while promoting innovation.

Studies on Nano Silo W, a functionalized nanosilica for stone protection, demonstrate effectiveness and stability. Applied to various stones, it has shown hydrophobicity and resistance to aging. Studies in Italy and Spain have evaluated the contact angle, capillary absorption, and color variation, confirming minimal chromatic alteration and little influence on permeability. Nano Silo W, both in its pure form and diluted, maintains good protective properties even after accelerated aging cycles, highlighting its validity as a water repellent.

Contemporary art experiments with polymers such as vinyl, acrylics, and alkyds. Since 1925, vinyl polymers (e.g., Mowilith) and acrylics (Rohm and Haas) have been used in Germany. In the 1960s, "acrylic" became synonymous with synthetic, confusing execution techniques. Restoration requires in-depth analysis, using techniques like FTIR and GC/MS. Cleaning polymer artworks is complex and carries risks of damage. Less invasive methods are being explored, such as rigid gels and dry cleaning. The conservation and restoration of contemporary art remain open challenges.

Silo 111 and Biotin R, when combined, offer effective protection against bacterial colonization on stone surfaces. Silo 111 is a hydrophobic siloxane, while Biotin R contains IPBC and OIT, molecules with low water solubility. By adding 5% of Biotin R to Silo 111, a synergistic effect is created: Biotin R prevents bacterial development on the siloxane, which, in turn, reduces water absorption into the material's pores, further limiting microbial growth. This combination has been successfully tested by the University of Roma Tre, showing promising results in the conservation of artworks and monuments.

Solvent-based and water-based woodworm treatments mainly differ in the carrier vehicle used to transport the active ingredient, typically permethrin. Solvents offer better penetration into the wood, while water-based products, often labeled as "eco-friendly," do not necessarily reduce toxicity or environmental impact. The safety of using these products depends on proper usage and individual protection. Furthermore, claims about gel-based woodworm products penetrating deep into the wood are often exaggerated and unsupported by scientific studies. Product registration as biocides is essential to ensure their reliability and safety.

The GUSTAV BERGER'S ORIGINAL FORMULA® ISOLATING PVA SPRAY VARNISH, also known as Isolating Varnish, is a liquid PVA (polyvinyl acetate) varnish designed to address specific issues in antique paintings undergoing multiple restorations. This varnish, ideal for evening out surfaces with alternating retouches and absorbent areas, is based on a blend of long-chain PVA resins, ensuring stability and flexibility. It is soluble in polar solvents and not suitable for modern oils or acrylics. Despite the softness of PVA resins, which can attract atmospheric particles causing graying, the varnish has shown low yellowing and good reversibility. It is not suitable as a final varnish but can be overpainted with various types of varnishes. It is also useful for fixing delicate glazes and allows for quick retouching. Its volatile composition minimizes leaching effects on less-aged oils, making it an essential product in certain restoration contexts.

In the field of restoration materials, the disappearance of some products is being observed. Cyclododecane and ammonium oxalate, the latter used since the 1990s for mural paintings and stone materials, are no longer available due to complex regulations and high costs. Momentive's Velvesil Plus is also no longer in production, but alternatives are being evaluated. Preventol RI 80 has been replaced by Preventol RI 50, with a reduced concentration from 80% to 50%, offering the advantage of not freezing at low temperatures, although careful dilution is required to maintain the effectiveness of the active ingredient.

After a one-year hiatus due to the lockdown and uncertainties of 2020, technical meetings have resumed in a new format. Initially, craft webinars were held on CTS EUROPE's YouTube page as a way to stay connected despite restrictions. The first meeting focused on the sanitization of museum environments and restoration laboratories using cold plasma technology.

In the field of education, a SMART program was launched in Florence, offering a three-year free course for Cultural Heritage Restoration Technicians, specializing in carved wooden artifacts, furnishings, and wooden structures. The course, which spans 2700 hours, includes classroom training and internships, and will run from April 2021 to February 2024. Finally, the National Association of Experts in Diagnostics and Applied Sciences for Cultural Heritage (ANEDbc) is organizing two days of training on April 17 and 18, featuring professional presentations, interviews with contemporary artists, and a roundtable discussion on the role of color in art, restoration, industrial production, and museum exhibitions.

The laboratories of the Center for Conservation and Restoration "La Venaria Reale" have developed a method for analyzing paper, identifying its historical and production characteristics. Using microchemical tests, it is possible to distinguish different types of paper based on the raw material and the production method. These tests have been adapted to be easily performed and interpreted even by non-specialized personnel.

Research has highlighted how the techniques and raw materials used in paper production have changed over time, influencing its properties. Understanding these variations is crucial in the field of conservation and restoration of cultural heritage. After preliminary tests, the most effective methods were selected and applied to paper samples, allowing for detailed analyses on both a macroscopic and microscopic scale. This process has led to the creation of an operational manual for the laboratories of the CCR, guiding the analysis of paper samples from the preparation of reagents to the interpretation of results.

The Scotch Tape Test, or peeling test, is a simple method to assess the effectiveness of consolidating products on deteriorated stones or mortars. It only requires a precision scale to weigh strips of adhesive tape before and after application to the treated material. The difference in weight indicates the material removed, inversely proportional to the consolidation achieved. Originally used to evaluate the strength of paints, the method was adapted for restoration by Mora and Torraca in 1965. However, it has limitations, providing only an index of surface consolidation without information about the internal effect of the consolidant.

The test is influenced by variables such as the type and size of the adhesive tape, the type of stone material, the force, and the speed of tape application and removal. To reduce errors, specific protocols have been proposed. Measurements must be repeated several times on the same area, with various approaches to data processing. Despite the variables, the test remains useful for analyzing the behavior of consolidants on the same material, offering a relative rather than absolute comparison.

"Tending Green" explores the movement towards more sustainable chemistry in restoration, highlighting the importance of safe solvents and materials. The EPA (Environmental Protection Agency) and the ECHA (European Chemicals Agency) promote the use of low-risk materials, with the EPA assigning the "Safer Choice Label" to compliant products. In restoration, the "green" shift began in the 1990s with the introduction of aqueous methods and low-toxicity solvents. The complexity of the issue includes solvent toxicity, their biodegradability, the energy required for production, and recyclability. New solvents like propylene carbonate, VOC-free, and low toxicity have been introduced, but research continues to find more sustainable alternatives. Materials from renewable sources, such as animal glues, natural resins, and agar-based gels, are used in restoration, along with initiatives to reduce the environmental impact of packaging. This "tending green" path is ongoing, with the goal of improving sustainability in the restoration sector.

The article inaugurates a section of the CTS Bulletin dedicated to significant restoration works, focusing on the "Terrace of the Geographical Maps" at the Uffizi Gallery, celebrating the expansion of the Medici family. The mural maps, created by Stefano Bonsignori and Ludovico Buti using the oil technique, depict the Medici's dominion in Tuscany. These works, enriched with naturalistic elements, mythological figures, and historical toponyms, have recently been restored by a team coordinated by the Opificio delle Pietre Dure. The restoration involved the use of both classical and unconventional materials, such as gels for cleaning oil paintings. The project is documented in the volume titled "The Terrace of the Geographical Maps at the Uffizi," which delves into various aspects of the restoration and the history of the maps.

The article discusses the use of Fluoline HY, a synthetic fixative, in the restoration of Giovanni Patricolo's "Deposition" in Palermo. This material, initially used as a hydrophobic and consolidating agent for stones and plasters, has proven to be effective in fixing matte paintings as well. Fluoline HY is appreciated for its low chromatic impact and ease of removal. In the restoration of the "Deposition," a water-sensitive artwork on cotton muslin, Fluoline HY was chosen for its minimal chromatic impact and reversibility. It was applied in a diluted form with acetone, ensuring homogeneous consolidation without altering the visual appearance. Additionally, a blend of Fluoline ST and Paraloid B72 was used for canvas re-adhesion to the support and as a binder for fillings, demonstrating its versatility and effectiveness in restoration.