3 CONCLUSION

This study demonstrates that Paraloid B-72 is a suitable material for use as a reversible barrier layer for epoxy joins in wood. It offers strength comparable to epoxy used alone as well as to the other proven and widely used barrier materials, Butvar B-98 and hide glue. Like these other barrier materials, Paraloid B-72 appears to offer some protection to underlying wood in the event that the epoxy bond is broken. Additionally, Paraloid B-72 was shown in practice to be a reversible barrier material in xylenes vapor. This quality factor offers advantages over Butvar B-98 and hide glue when making repairs near finished, painted, or otherwise solvent-sensitive surfaces. This study also demonstrates that Paraloid B-67 is not a suitable material for use as a reversible barrier layer for epoxy joins in wood. Paraloid B-67 failed both strength and reversibility tests.

ACKNOWLEDGEMENTS

The authors would like to especially thank the J. Paul Getty Museum's Brian Considine, Jane Bassett, Julie Wolfe, George Johnson, and Mark Mitton of Decorative Arts and Sculpture Conservation for their unstinting support and great help throughout the project; Jerry Podany of Antiquities Conservation for sharing his knowledge and experience with barrier coatings; Stefan Simon of the Getty Conservation Institute for permission to use the institute's equipment, and the institute's Urs Mueller for providing cheerful advice, Instron training, and setup; and Jane Down of the Canadian Conservation Institute for her insight and guidance.