CONSERVATION / SAVING ADOBE : A Down-to-Earth Assault on an Age-Old Problem : Experts will gather in New Mexico to share ways to preserve structure and spirit of mud-brick buildings.

Out in the New Mexico desert, rows of man-made adobe walls lined up like tombstones are being treated with chemicals and soaked with water. Not far away, remnants of a 19th-Century adobe fort sit under a canopy of fabric specially color-coordinated to blend in with the Southwestern landscape.

These simple structures at Ft. Selden soon will be the object of intense scrutiny as representatives of 30 countries from China to Chile gather next week in nearby Las Cruces to share research in how to halt deterioration of one of the oldest building materials on Earth.

Co-sponsored by the Getty Conservation Institute of Marina del Rey and five other public and private agencies, the sixth International Conference on the Conservation of Earthen Architecture--the biggest so far and the first to be held in the United States--will bring together scientists, archeologists, architects and conservators.

Although the conference will focus on the preservation of historic monuments made of sun-dried mud brick, organizers hope it will have a broader application, especially for developing countries. Nearly half of the world’s population is believed to live in homes constructed from adobe, whose earliest known use (in unbaked form) dates to nearly 8000 BC in Jericho.

Participants will hear from New Mexicans involved in community programs to maintain local churches and Moroccans attempting to revitalize oasis villages. “People will be brought into communication in a way that does not deal only with, shall I say, dry-as-dust structures,” said Neville Agnew, director of scientific programs for the Getty institute, “but also with social history, social interaction and the maintenance of traditions.”

In the United States, adobe usually is associated with the Southwest, where it is used in everything from multimillion-dollar haciendas to Department of Housing and Urban Development units built for Pueblo Indians. But adobe structures of varying architectural styles are found in various parts of the country.

Despite its many virtues--it is cheap and accessible and adapts to desert climates--adobe is vulnerable to rain, earthquakes, wind, fluctuation in temperature and humidity and damage from insects and rodents. Many important historical sites are showing the effects of long-term neglect.

Since 1972, New Mexico state officials have been conducting conservation experiments at Ft. Selden, a military post built in 1867 to protect the surrounding Mesilla Valley and abandoned 100 years ago. In 1987, the Getty Conservation Institute, funded by the J. Paul Getty Trust, added its scientific expertise and resources to what was essentially a “folk” experiment testing “all sorts of interesting things” from store-bought chemicals to cactus juice, according to Thomas J. Caperton, director of New Mexico State Monuments.

Getty scientists report promising results from two types of chemicals that can be applied to adobe walls. One--alkoxysilane--is more easily absorbed than the other but is very expensive. The second--isocyanate--is cheaper but more difficult to work with. Both have “a tendency to slightly darken the appearance, and this might not be acceptable to people, especially to conservators,” said Richard L. Coffman, a Getty geologist.

Experimenters have not used chemicals on historic relics, choosing instead to build new walls for test purposes. “A big buzzword in conservation science is ‘reversibility,’ ” or the ability to undo the test, said chemist Charles Selwitz, a Getty institute consultant.

Reversibility explains the appeal of the so-called hexashelters developed by Getty scientists. These are tent-like structures made of loosely woven fabrics--called “aerotextiles”--and secured by concrete footings. They can be placed over monuments, protecting them from the elements while still allowing access for visitors.

But, like most conservation measures, this has a downside, according to Michael Taylor, a National Park Service archeologist who is co-chairman of the conference with Agnew. The shelter itself may exacerbate wind turbulence, he said.

Agnew and his crew are working with other materials to protect newly dug-up relics from disintegration. Scientists have learned that the safest place for the discoveries is right back underground. Wrapping them with so-called geotextiles keeps insects and rodents away and enables archeologists to easily retrieve them.

In New Mexico, scores of sites have been “reburied” while awaiting new technology that will ensure their future existence, Taylor said.