Skip to main content

Testing the Effectiveness of Protocols for Removal of Common Conservation Treatments for Radiocarbon Dating

  • Fiona Brock (a1), Michael Dee (a2) (a3), Andrew Hughes (a4), Christophe Snoeck (a5), Richard Staff (a2) (a6) and Christopher Bronk Ramsey (a2)...

To achieve a reliable radiocarbon (14C) date for an object, any contamination that may be of a different age must be removed prior to dating. Samples that have been conserved with treatments such as adhesives, varnishes or consolidants can pose a particular challenge to 14C dating. At the Oxford Radiocarbon Accelerator Unit (ORAU), common examples of such substances encountered include shellac, the acrylic polymers Paraloid B-67 and B-72, and vinyl acetate-derived polymers (e.g. PVA). Here, a non-carbon-containing absorbent substrate called Chromosorb® was deliberately contaminated with a range of varieties or brands of these conservation treatments, as well as two cellulose nitrate lacquers. A selection of chemical pretreatments was tested for their efficiency at removing them. While the varieties of shellac and Paraloid tested were completely removed with some treatments (water/methanol and acetone/methanol/chloroform sequential washes, respectively), no method was found that was capable of completely removing any of the vinyl acetate-derived materials or the cellulose nitrate lacquers. While Chromosorb is not an exact analog of archaeological wood or bone, for example, this study suggests that it may be possible to remove aged shellac and Paraloid from archaeological specimens with standard organic solvent-acid-base-acid pretreatments, but it may be significantly more difficult to remove vinyl acetate-derived polymers and cellulose nitrate lacquers sufficiently to provide reliable 14C dates. The four categories of conservation treatment studied demonstrate characteristic FTIR spectra, while highlighting subtle chemical and molecular differences between different varieties of shellac, Paraloid and cellulose nitrate lacquers, and significant differences between the vinyl acetate derivatives.

Corresponding author
*Corresponding author. Email:
Hide All
Brock F, Higham T, Ditchfield P, Bronk Ramsey C. 2010. Current pretreatment methods for AMS radiocarbon dating at the Oxford Radiocarbon Accelerator Unit (ORAU). Radiocarbon 52(1):103112.
Brock F, Ostapkowicz J, Wiedenhoeft AC, Bull I. Radiocarbon dating wooden carvings and skeletal remains from Pitch Lake, Trinidad. Radiocarbon, in press.
Bruhn F, Duhr A, Grootes PM, Mintrop A, Nadeau M-J. 2001. Chemical removal of conservation substances by “soxhlet”-type extraction. Radiocarbon 43(2A):229237.
Berglund BE, Hakansson S, Lagerlund E. 1976. Radiocarbon dated mammoth (Mammuthus primigenius Blumenbach) finds in South Sweden. Boreas 5(3):177191.
Caforio L, Fedi M, Liccioli L, Salvini A. 2013. The issue of contamination by synthetic resins in radiocarbon dating: the case of a painting by Ambrogio Lorenzetti. Procedia Chemistry 8:2834.
Chapman S, Mason D. 2003. Literature review: the use of Paraloid B-72 as a surface consolidant for stained glass. Journal of the American Institute for Conservation 42(2):381392.
Dee MW, Brock F, Bowles AD, Bronk Ramsey C. 2011. Using a silica substrate to monitor the effectiveness of radiocarbon pretreatment. Radiocarbon 53(4):705711.
D’Elia M, Gianfrate G, Quarta G, Giotta L, Giancane G, Calcagnile L. 2007. Evaluation of possible contamination sources in the 14C analysis of bone samples by FTIR spectroscopy. Radiocarbon 49(2):201210.
France CAM, Giaccai JA, Cano N. 2011. The effects of PVAc treatment and organic solvent removal on δ13C, δ15N, and δ18O values of collagen and hydroxyapatite in a modern bone. Journal of Archaeological Science 38:33873393.
France CAM, Giaccai JA, Doney CR. 2015. The effects of Paraloid B-72 and Butvar B-98 treatment and organic solvent removal on δ13C, δ15N, and δ18O values of collagen and hydroxyapatite in a modern bone. American Journal of Physical Anthropology 157(2):330338.
Horie V. 2010. Materials for Conservation: Organic Consolidants, Adhesives and Coatings. 2nd edition. London: Routledge.
Johnson JS. 1994. Consolidation of archaeological bone: a conservation perspective. Journal of Field Archaeology 21(2):221233.
Khairuddin Pramano E, Utomo SB, Wulandari V, A’an Zahrotol W, Clegg F. 2016. The effect of polyethylene glycol on shellac stability. IOP Conference Series: Materials Science & Engineering 107:012066.
Koob SP. 1979. The removal of aged shellac adhesive from ceramics. Studies in Conservation 24(3):134135.
Koob SP. 1982. The instability of cellulose nitrate adhesives. The Conservator 6:3134.
Koob SP. 1984. The continued use of shellac as an adhesive – why? Studies in Conservation 29(Sup1):103.
Koob SP. 1986. The use of Paraloid B-72 as an adhesive: its application for archaeological ceramics and other materials. Studies in Conservation 31:714.
Larney J. 1971. Ceramic conservation in the Victoria and Albert Museum. Studies in Conservation 16:6982.
Law IA, Housley RA, Hammond N, Hedges REM. 1991. Cuello: resolving the chronology through direct dating of conserved and low-collagen bone by AMS. Radiocarbon 33(3):303315.
Moore KM, Murray ML, Schoeninger MJ. 1989. Dietary reconstruction from bones treated with preservatives. Journal of Archaeological Science 16:437446.
Nel P. 2006. A preliminary investigation into the identification of adhesives on archaeological pottery. AICCM Bulletin 30:2737.
Nel P, Lau D. 2009. Identification of a formulation change in a conservation grade adhesive. In: Ambers J, Higgit C, Harrison L, Saunders D, editors. Conference proceedings, Holding it all Together, Ancient and Modern Approaches to Joining, Repair and Consolidation, British Museum. London Archetype Publications. p 99–106.
Nel P, Lonetti C, Lau D, Tam K, Sagona A, Sloggett RS. 2010. Analysis of adhesives used on the Melbourne University Cypriot pottery collection using a portable FTIR-ATR analyser. Vibrational Spectroscopy 53:6470.
Nishimoto H. 2011. High precision radiocarbon dating of archaeological waterlogged wood: focusing on wooden poles forming circular structures at the Mawaki site [PhD thesis]. Nagoya University, Japan.
Oddy WA. 1973. An unsuspected danger in display. Museums Journal 73:2728.
Ohlídalová M, Kučerová I, Novotná M. 2006. Identification of acrylic consolidants in wood by Raman spectroscopy. Journal of Raman Spectroscopy 37(10):11791185.
Ostapkowicz J, Schulting RJ, Wheeler R, Newsom L, Brock F, Bull I, Snoeck C. 2017. East-central Florida pre-Columbian wood sculpture: radiocarbon dating, wood identification and strontium isotope studies. Journal of Archaeological Science: Reports 13:595608.
Ramirez Rozzi FV, d’Errico F, Vanhaeren M, Grootes PM, Kerautret B, Dujardin V. 2009. Cutmarked human remains bearing Neanderthal features and modern human remains associated with the Aurignacian at Les Rois. Journal of Anthropological Sciences 87:153185.
Robinet L, Thickett D. 2003. A new methodology for accelerated corrosion testing. Studies in Conservation 48(4):263268.
Shashoua Y, Bradley SM, Daniels VD. 1992. Degradation of cellulose nitrate adhesive. Studies in Conservation 37(2):113119.
Shelton SY, Chaney DS. 1993. An evaluation of adhesives and consolidants recommended for fossil vertebrates. In: Leiggi P, May P, editors. Vertebrate Palaeontological Techniques Volume 1. Cambridge: Cambridge University Press. p 3545.
Stevens RE, Hedges REM. 2004. Carbon and nitrogen stable isotope analysis of northwest European horse bone and tooth collagen, 40,000 BP–present: palaeoclimatic interpretations. Quaternary Science Reviews 23:977991.
Tuross N, Fogel MI. 1994. Exceptional molecular preservation in the fossil record: the archaeological, conservation and scientific challenge. In: Scott DA, Meyers P, editors. Archaeometry of Pre-Columbian Sites. Los Angeles: The Getty Conservation Institute. p 367380.
Yuan S, Wu X, Liu K, Guo Z, Cheng X, Pan Y, Wang J. 2007. Removal of contaminants from oracle bones during sample pretreatment. Radiocarbon 49(2):211216.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

  • ISSN: 0033-8222
  • EISSN: 1945-5755
  • URL: /core/journals/radiocarbon
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 6
Total number of PDF views: 42 *
Loading metrics...

Abstract views

Total abstract views: 222 *
Loading metrics...

* Views captured on Cambridge Core between 9th August 2017 - 11th December 2017. This data will be updated every 24 hours.