Potential substitutes for discontinued poly(vinyl acetate) resins used in conservation

ABSTRACT

Several poly(vinyl acetate) resins that continue to be important and useful in many areas of conservation are no longer available, namely, the AY series manufactured by the Union Carbide Corporation (AYAC, AYAA, AYAF, AYAT), and Mowilith 20 originally manufactured by the Hoechst Corporation. To identify potential substitutes, comparable resins were obtained from manufacturers and their properties were investigated and compared to the discontinued resins. Non-instrumental analysis was conducted to assess basic properties and measure relative viscosity. In addition, instrumental analysis was used to measure molecular weight, glass transition temperature, and chemical composition. The collected data were compiled and evaluated to determine potential substitutes for each of the discontinued resins.

RÉSUMÉ

Plusieurs résines en acétate de polyvinyle qui demeurent importantes et utiles dans plusieurs domaines de conservation-restauration ne sont plus manufacturées, dont celles faisant partie du groupe AY produit par l’Union Carbide Corporation (AYAC, AYAA, AYAF, AYAT) ainsi que le Mowilith 20 à l’origine produit par la Hoechst Corporation. Afin de trouver des substituts potentiels, des résines semblables furent obtenues de la part des manufacturiers et leurs propriétés furent étudiées et comparées à celles des résines en fin de série. Des analyses non instrumentales ont été effectuées dans le but d’évaluer leurs propriétés de base et de mesurer leur viscosité relative. De plus, des analyses instrumentales furent mises en œuvre afin de mesurer leur poids moléculaire, leur température de transition vitreuse ainsi que leur composition chimique. Toutes les données furent recueillies et évaluées afin de déterminer quelle nouvelle résine pourrait être utilisée comme substitut pour chacune des résines en fin de série. Traduit par Carole Dignard.

RESUMO

Muitas das resinas de polivinil acetato que continuam a ser importantes e úteis em diversas áreas da conservação já não se encontram disponíveis, nomeadamente, as séries AY fabricadas pela Union Carbide Corporation (AYAC, AYAA, AYAF, AYAT) e a resina Mowilith 20, originalmente, fabricada pela Hoechst Corporation. Para identificar substitutos potenciais, resinas semelhantes foram obtidas dos fabricantes e as suas propriedades foram investigadas e comparadas às das resinas descontinuadas. Análises não instrumentais foram conduzidas para analisar propriedades básicas e medir a sua viscosidade relativa. Além destes exames, a análise instrumental foi utilizada para medir o peso molecular, a temperatura vítrea de transição e a composição química. Os dados reunidos foram compilados e avaliados para determinar substitutos potenciais de cada uma das resinas descontinuadas. Traduzido por Teresa Lança.

RESUMEN

Varias resinas de poli (acetato de vinilo) que siguen siendo importantes y útiles en muchas áreas de conservación, ya no están disponibles, a saber, la serie AY fabricada por Union Carbide Corporation (AYAC, AYAA, AYAF, AYAT) y Mowilith 20 originalmente fabricada por la Corporación Hoechst. Para identificar sustitutos potenciales se obtuvieron de los fabricantes resinas comparables y se investigaron sus propiedades y se compararon con las resinas descontinuadas. Se realizó un análisis no instrumental para evaluar las propiedades básicas y medir la viscosidad relativa. Además, se utilizó el análisis instrumental para medir el peso molecular, la temperatura de transición vítrea y la composición química. Los datos resultantes se recopilaron y evaluaron para determinar los sustitutos potenciales para cada una de las resinas descontinuadas. Traducido por Amparo Rueda.

KEYWORDS:

• Poly(vinyl acetate)
• PVAC
• molecular weight
• glass transition temperature
• viscosity
• AYAC
• AYAA
• AYAF
• AYAT
• Mowilith 20

Acknowledgements

The authors would like to thank the American Institute of Conservation (AIC), as this work was supported in part by a Foundation for Advancement in Conservation (FAIC) Individual Professional Development Scholarship. Much of the work at the AMNH relied upon the contributions of interns Melissa Tan and Loren Teetelli, as well as the support and advice of colleagues including Judith Levinson, Gabrielle Tieu, Amy Davidson, and Jessica Walthew. In addition, we would like to thank Velson Horie, Robert Feller, and Chris McGlinchey who offered information and guidance during our research.

Disclosure statement

No potential conflict of interest was reported by the authors.

Sources of materials

McGean: PVA B-15 and PVA B-25 (Discontinued)

McGean

2910 Harvard Avenue

Cleveland, OH 44105 USA

Phone: [phone]

Fax: [phone]

McGean USA

38521 Schoolcraft Road

Livonia, MI 48150 USA

Phone: [phone]

http://www.mcgean.com/sp_product/adhesives.htm

Synthomer: ADS 206, ADS H155, ADS 190, M20, M30, M50 and M60

Synthomer

Central Rd.

Templefields, Harlow

Essex CM20 2BH UK

Phone: [phone]

Fax: [phone]

https://www.synthomer.com/

US Distributor:

Palmer Holland

25000 Country Club Blvd., Ste., 444

North Olmsted, OH 44070 USA

Phone: [phone]

https://www.palmerholland.com/

Vinavil: K40, K50, K55, K60 and Raviflex BL1S, BL5S, BL6S, BL7S

Vinavil Americas Inc.

2900 Francis-Hughes

Laval QC H7L 3J5 Canada

Phone: [phone]

Fax: [phone]

Vinavil Americas Corp.

530 Industrial Dr.

West Chicago, IL 60185 USA

Phone: [phone]

Fax: [phone]

http://www.vinavil.com/

Wacker: Vinnapas B 1.5 Sp, B 5 Sp, B17 Sp, B 30 Sp, B 60 Sp, B 100 Sp, UW 1 TR, UW 2 TR and UW 4 TR.

(Note: “TR” variety of the UW line has been discontinued, UW resins with an “FS” designation are currently available. These contain more added fumed silica).

Wacker Chemie AG

Hauptverwaltung

Hanns-Seidel-Platz 4

81737 München, Germany

https://www.wacker.com

Notes on contributors

Samantha Alderson is a conservator in the Anthropology Division of the American Museum of History. She received a MA in art and history archaeology, and an advanced certificate in conservation in 1994 from the Conservation Center of the Institute of Fine Arts, New York University (New York), where she is now a lecturer, teaching advanced courses in objects conservation. Her research interests include adhesives and consolidants, climate monitoring systems, ancient Meso-American ceramics, and material culture of the Pacific Northwest Coast. Address: American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA. E-mail: [email protected].

Jane L. Down (retired) graduated from Queen’s University (Kingston, Ontario) in 1973 with an Honors Bachelor of Science in chemistry and mathematics. She joined CCI in 1978 and, as a senior conservation scientist, was responsible for all adhesive research carried out at the Institute. Jane published many papers, presented her work at conferences, supervised interns, organized and taught adhesive workshops, and organized and chaired CCI symposia. She carried out research on epoxy resins, poly(vinyl acetates), acrylics, vinyl acetate/ethylene copolymers and various tapes and heat-set tissues. In 2002, Jane received the Preparator’s Award from the Society of Vertebrate Paleontology to investigate cyanoacrylate adhesives for fossils. Jane also received two Department of Canadian Heritage Deputy Minister Awards for her contributions to the Archimedes Palimpsest Project (2002) and Symposium 2003, and two CCI Director General’s Awards for contributions to Symposium 2011 and the publication of her book Adhesive Compendium for Conservation (2015).

Christopher A. Maines received a PhD in physical chemistry from the University of California, Berkeley in 1990. After a three-year fellowship in the scientific research department at the National Gallery of Art, he became a conservation scientist at the Smithsonian Institution’s Freer Gallery of Art and Arthur M. Sackler Gallery investigating East Asian lacquer. In 1997 he returned to the National Gallery of Art as a conservation scientist where his research is focused on the stability and working properties of conservation, exhibition, and storage materials, developing methods for microanalysis of organic materials from works of art, and understanding how working practices of twentieth century photographers affected the chemistry and thus the appearance and stability of their prints. Address: National Gallery of Art, 2000B South Club Drive, Landover, MD 20785, USA. E-mail: [email protected].

R. Scott Williams (retired) was an analytical chemist and senior conservation scientist at the Canadian Conservation Institute since 1977. He performed thousands of analyses of materials from all types of museum and cultural objects: paintings, paper, textiles, and ethnographic and archaeological objects. His special interest was plastics, particularly the degradation, interaction, and conservation of museum objects and storage materials composed of plastics and other synthetic materials. His work included the development of portable mid and near infrared (IR) spectroscopy to carry out non-destructive on-site chemical analysis of objects at heritage institutions. Scott published or presented more than 80 papers for conservation, museum, and scientific professionals.

Gregory S. Young (B.Sc. Honors, Ph.D.) (Retired) studied cell biology at Carleton University, Ottawa, and developed analytical technologies for collagenous materials at the University of London. Since 1977 at the Canadian Conservation Institute as Senior Conservation Scientist, he undertook analysis and fundamental research of natural materials. He has published in several fields, including artists’ materials, stone bio-deterioration, paleobotany, wet organic archaeological materials, and analytical development. His most recent research included study of the effects of fumigants on a model protein, the virtual deconstruction of a historic flag from the War of 1812 using image analysis, and the application of hyperspectral imaging in fine art.

ORCID

Samantha Alderson http://orcid.org/0000-0003-2351-9609

Notes

1 Union Carbide supplied AYAB in two forms: as a solid and in solution. The solution was sold under the trade names “Vinylseal A-70” or “Palmer Cement” (Berger 2000; Union Carbide 1942). A review of Union Carbide publications 1942–1989 and the conservation literature indicates that the AYAB designation was used for two different solid grades. The earlier literature lists AYAB with a molecular weight higher than AYAC (Feller 1985; Skeist 1962; Union Carbide ca. 1960), and this is the grade generally referenced in art conservation literature. However, later technical literature from Union Carbide lists AYAB as having a molecular weight below AYAC (Union Carbide 1989) – it is unclear if this lower molecular weight AYAB was used in conservation.

2 The “Sp” at the end of the lower molecular weight Wacker grades stands for “Special” indicating the resin is food grade. (Low molecular weight grades of PVAC are used as a gum base as well as in other consumable applications in the food and pharmaceutical industries.) The “TR” at the end of the higher grades stands for “translucent” indicating only a trace amount of fumed silica is present. These grades were discontinued in 2013 during the course of this project (Hansen 2013). The currently supplied “UW” grades are designated “FS” and contain a more significant amount of fumed silica than the “TR” grades.

3 A second set of Vinavil Raviflex samples was obtained and included in evaluations when it was discovered that the morphology of the bulk supply had changed from chunk to pastilles.

Additional information

Funding

This work was supported by Foundation of the American Institute for Conservation of Historic and Artistic Works, now the Foundation for Advancement in Conservation (FAIC).