5 CONCLUSIONS

A LARGE selection of materials are luminescent, including natural resins, waxes, oils, proteinaceous materials, gums, and mixtures of these materials. Luminescence can easily be detected and recorded from 100-micron regions of all the materials studied. In some cases, the luminescence peak maximum can be used to differentiate between samples. Additionally, the measurements demonstrate that changes in the wavelength of excitation and the sample temperature can cause spectral changes that may also be useful. Spatial inhomogeneities of materials can also be studied. To completely assess the utility of the technique, emission lifetimes as well as studies of wavelength dependences and temperature effects should be made. Further investigations should also explore in more detail the properties of mixtures of binding media with one another and with pigments.

ACKNOWLEDGEMENTS

THIS WORK was made possible by a contract from the Getty Conservation Institute. The authors thank Michele Derrick, James Druzik, Frank Preusser, and Max Saltzman for helpful discussions.