There are general guidelines. Photographs and metals that can be etched by fingerprints are almost always best handled with gloves. Textiles, paper, glazed ceramics and glass (slippery but easily cleansed) are usually best handled with regularly washed hands. There will be exceptions to everything.
The good news for framers and mount makers is that mounts and supports that eliminate the need for direct touch are new best practice. UBC Anthropology Museum recently went through a huge move and revamp wherein all or most of their collection can be closely examined without touching, by well designed mounts.
But they are also exploring the exciting dynamic between the need for preservation and the need for cultural use. They work with the communities whose artifacts they house so that items can be used for the cultural/ceramonial use for which they were created. This is an new and pleasant change from museums being a repository for "dead" items:
"“When You Don’t Cry Over Spilt Milk: Collections Access at the UBC Museum of Anthropology During the Renewal Project” was presented by Shabnam Honorbakhsh and co- authored by Heidi Swierenga and Maurau Toutloff. The University of British Columbia’s Museum of Anthropology in Vancouver has some 38,000 objects, most of which were placed on visible storage in the 1970’s with the intent of 100% visual access. In the spring of 2004, there was a renewal project, and the museum did considerable behind-the-scenes work as well as continued to consider collection access as an ever-evolving philosophy. The hands-on work included survey, barcode assignment, digitization, testing for pesticides, mount making, packing, moving and finally installation. It sounded like consultation with Native researchers was suggesting that 4 views was the average number of images needed to really see an artifact. The collection can be searched online at MOACAT Also check out how their collections section on their website starts off with some cool downloadable reference documents. I’m definitely right-clicking on some of those! There is also an exciting joint collaborative project to facilitate collaborative study of Northwest Coast artifacts called the Reciprocal Research Network. Chilkat weaver William White (Tsimshian) was quoted: “One of the things that is very important to me is accessibility for my people to come into the museum and be treated with respect and honor.” There was also an example of a bronze statue of Vishnu in the collection who was resanctified for worship by the Vancouver Hindu community. The video of the ritual renewal involved water, honey, oil, milk, fruit and other substances being applied to the statue. Afterwards, it was cleaned, dried, and treated in a desiccation chamber. Marian Kaminitz of the National Museum of the American Indian mentioned after the talk that museums have a societal opportunity to enhance advancement of indigenous societies from a colonialist time to a regeneration time. It seemed to me like there was a more intense focus on the human, social, and interpersonal aspects of our profession and responsibilities at this meeting."