Fossil preparation is going through a transition - becoming less of an artisan trade and more of a profession. Preparators need to be able to communicate accurately with each other and with colleagues in related fields (conservators and conservation scientists, material scientists and chemists). There is a very specific nomenclature terminology for adhesives. This document helps define some of these terms.
It is essential that preparators understand the nomenclature for adhesives to ensure that communication with colleagues, researchers and other allied professionals (e.g., conservators, conservation and/or material scientists, chemists) involved in the care and curation of fossil specimens is clear and accurate. Adhesives can be discussed according to their:
- Properties (e.g., heat-set, solvent evaporating) – these terms describe the way in which the adhesive acts. For more on these properties read on below.
- Chemical family (e.g., cyanoacrylates, polyvinyl butyrols, epoxies, acrylic resins, etc.) - Products in the same family will have the same basic chemical composition.
- Trade or product line name (e.g., Paleobond, Acryloid, Butvar, Duco, Devcon, etc.) - These names are created for marketing and are subject to change at the manufacturers will or discretion.
- Grade (e.g., PB40, 100, 750, or Paraloid B-72, B-76, etc.) – the grade is a way of specifying a particular product. Each grade of within a chemical family will have the same basic composition but will differ slightly in chemical formula. Sometimes the number refers to a specific aspect of the adhesive – such as its molecular size, other times it is a marketing tool.
With all names it is unsurprising that there is confusion. Issues commonly arise due to:
Interchangeable product names
A manufacturer may sell the same product under different names in different countries. For example, Rohm and Hass markets its ethyl methacrylate copolymer in the North America under the name Acryloid and in Europe as Paraloid. In 1997 the name Acryloid was dropped and the company began using Paraloid for this product line worldwide. Similarly, Rohm and Hass’s product line of acrylic colloidal suspensions is known as Primal in Europe and Rhoplex in North America. The Conservation & Art Material Encyclopedia Online database created by the Museum of Fine Arts, Boston is an excellent resource for checking on the formulation of specific products.
A lack of specificity
It is not enough to list B72, B76, or B15 as the adhesive used. B-72 could refer to Paraloid B-72, which is commonly used on fossils or Butvar B72 which is rarely used. Butvar B76 is actually a mix of three different polymers which are also used in Butvar B98 but the ratios are different in each. B15 normally refers to the product Vinac B15 but that adhesive is no longer made by Air Products and the designation is now given to a new product – PVA B15 made by McGean Company.
Change in a proprietary product line
Most adhesives whether from a trade supplier or corner hardware store are proprietary. The manufacturer can change its composition at will. Sometimes this happens as a company is bought out (e.g. Butvar, originally manufactured by Monsanto was transferred to Solutia). Sometimes is purposeful so the product can be marketed as “new and improved”. Generally the standards for industrial adhesives is higher than for household products but if you notice that an adhesive looks or smells different, or has different working properties, there may have been a change in formulation. Those changes that might not be important for a use around the home can have a profound impact when applied to a fossil specimen.
Ultimately the best way to avoid confusion when naming an adhesive in a treatment report is to use both the trade name and the grade (e.g. Butvar B76) and, when possible, the actual chemical composition should be given (e.g. Paraloid B-72 – ethyl methacrylate copolymer).
Download Velson Horie’s Adhesives Glossary here. Learn more on the topic by taking the distance learning course Chemistry for Conservators through International Academic Projects.
Much of the information on this topic was excerpted and adapted from An Introduction To Solution And Reaction Adhesives For Fossil Preparation by Amy Davidson and Samantha Alderson published in Methods in Fossil Preparation Proceedings of the First Annual Fossil Preparation and Collections Symposium, edited by Matthew A. Brown, John F. Kane, and William G. Parker. Petrified Forest, 2009. To learn more about the other talks given at the symposium visit the National Park Service Petrified Forest Fossil Preparation and Collections Symposium page. Click here to buy a copy of the published proceedings.
Download the document Adhesives and Adhesion by Jonathan Thornton, a professor in the conservation program at Buffalo State College. This document covers topics including:
History, Terminology, Choice of Adhesive, and gives information on a wide range of specific adhesives used in conservation.
Download Adhesives and consolidants in geological and paleontological applications; part one: introduction, guide, health and safety, definitions and part two: wall chart. Society for the Preservation of Natural History Collections. 1997. vol 1 leaflet 2. By Ann Elder, Scott Madsen, Gregory Brown, Carrie Herbel, Chris Collins, Sarah Whelan, Cathy Wenz, Samantha Alderson and Lisa Kronthal.