Analysis of paper gloss

Standard techniques for the measurement of paper gloss are capable of providing highly repeatable indices of the gloss phenomenon. However, it is well known that the gloss phenomenon involves more than can be represented by a single number. A recently developed instrument called a microgoniophotometer has been applied to the characterization of paper gloss. The Bi-directional Reflectance Distribution Function (BRDF) plots generated by this device were shown to be related quantitatively and directly to Fresnel\u27s law of specular reflection and to the surface roughness of the sample. Unlike standard gloss meter measurements, the BRDF enables the analyst to distinguish between effects of surface roughness and the Fresnel reflectance factor. Moreover, the analysis provides a way to characterize quantitatively the importance of sub-surface specular reflections to the overall gloss of a coated paper

New Materials for the Coating of Outdoor Bronze

Bronze surfaces exposed to an outdoor environment face many conservation challenges. Dramatically varying conditions of temperature, moisture and pollution typically result in material loss (as pitting and dissolution) and chemical alteration, accompanied by color change. Without intervention, bronze left to weather outdoors will continue to deteriorate until little remains of the physical substance and appearance of the original patinated surface. However, the processes of decay can be slowed significantly through the use of coatings. While waxes and lacquers have long been available to conservators, these coatings typically require annual maintenance to retain a high level of performance. With the development of a number of new treatment systems, there seems to be the potential to combine improved protection with enhanced coating durability, considerably extending the time between conservation interventions. Several innovative coatings were evaluated, in comparison to current practices. This research has involved the preparation of coated coupons for testing with the use of QUV accelerated weathering. A number of ASTM standard test methods were used to study the samples before and after QUV exposure