4 4. CONCLUSIONS

If fabric is chosen carefully, textile covers are an inexpensive, reusable, and effective means of reducing the exposure of museum objects to UV radiation. The fabric characteristics that most influence UV transmission are mass, thickness, and color: the higher the mass and thickness and darker or more saturated the color, the less UV radiation transmitted through the fabric. Three fabrics reported in this study met Thomson's (1986) criterion of blocking 99% UV, a black 50/50 polyester/cotton double knit and a black stretch knit of 87% nylon and 13% spandex. Tyvek transmits 2% of the UV radiation, but has the important advantage in the museum context of being both waterproof and much lighter in weight than either the nylon/spandex or the double knit. The natural pigment in unbleached cotton muslin makes it a more effective UV screen than bleached cotton. Spunbonded webs with low cover (Cerex and Reemay) transmit 39% and 20% of the UV, respectively, and so are not useful covers for light-sensitive objects.

ACKNOWLEDGEMENTS

This research was funded in part by the Endowment Fund for the Future at the University of Alberta. The Government of Canada Summer Career Placement program also provided support for two undergraduate students of human ecology. We recognize the significant contributions of Jennifer Moroskat and Tannis Grant to this research project.