Nancy Nitzberg is no literary critic, but she can really take a book apart.

And put it back together.

Nitzberg, 48, is a book conservator, skilled in the art of repairing the torn pages, broken bindings, and frayed leather covers of old books. Very old books.

Her Elkins Park workshop, stuffed with black iron book-making tools that were old in the 1800s, looks like Ben Franklin's basement. A seven-foot-long paper cutter has a blade like an Arabian sword. A collection of huge vises stands ready to squeeze new starch into the yard-long spines of ancient books.

Nitzberg's 11-year-old business is called Book Care, and it has kept her surprisingly busy, she said in an interview Friday.

Nitzberg had learned her craft and toiled in libraries for a decade before launching out on her own. She didn't look back. "I have never had more work, more interesting projects," she said.

On her workbench was a fat English law book, dated 1660, with many of its weathered pages separated from the rotted binding. With surgical care, handmade Japanese tissue paper, and a pot of home-cooked wheat-starch paste, Nitzberg was reconstructing the tome for the rare-book collection of the University of Pennsylvania.

Her clients also include Temple University; local rare-book dealers; historical societies; collectors; and a smattering of individuals wanting to preserve heirloom volumes, disintegrating scrapbooks and family Bibles.

The expertise does not come cheaply. Nitzberg charges a minimum of $75, even if the job is a single torn page. She said recent repairs to a two-volume 15th-century German Bible for Princeton Theological Seminary cost the institution about $2,500.

Nitzberg is careful to point out that her work is less "restoration" than "conservation" of old books. Her aim is to "stop the damage," she said.

"I'm not trying, necessarily, to make the book look like it did when it was brought home 100 years ago," she said. She tries, instead, to "stabilize" a book by washing the acid from soiled pages, patching tears, even separating old cloth covers from their cardboard backings so the covers can be re-glued to fresh boards.

"The most nerve-wracking experience I ever had was the first time I saw someone else wash a piece of paper," she said. Nitzberg was a young intern at a Boston library when she watched a conservator dipping the pages of an aged book in a tray of water.

"I expected it to dissolve as a tissue, but it didn't. Washing paper is a positive thing in that, chemically, it rejuvenates" the paper fibers.

Demand for conservators' skills is growing, Frank Mowery, head of conservation at the Folger Shakespeare Library in Washington, said. "People are realizing that if you have something in your possession - a family heirloom, a work of art - it has to be maintained in good condition to retain its value, and these things are getting more and more valuable," he said.

Mowery said Nitzberg, whom he knows, got "a head start" on many colleagues by going full time with her own business. Besides, "institutions generally don't pay very well," he added.

The world of book conservators is a small one. The 3,100-member American Institute for Conservation of Historic and Artistic Works includes 900 members in its Book and Paper Group - professionals in the preservation and conservation of artifacts and collections of paper-based materials.

Another group, the Guild of Book Workers, has 1,000 members. Nitzberg belongs to both organizations.

"It's not a highly populated profession," she said.

Nitzberg earned graduate and undergraduate degrees in fine art at Boston University. In 1982, she took what she figured would be a short-term job in "book repair" at the Harvard College Library. "After a week, I knew it was what I wanted to do," she said.

She went on to earn a second master's degree, this one in library service, and a certification in book conservation, from Columbia University. She interned at the rare-book-conservation section of the Library of Congress.

Later, she held jobs as assistant conservator at the Yale University Library and as a book conservator for the nonprofit Conservation Center for Art and Historic Artifacts in Center City.

In those jobs, "I was aware of a lot of demand" for book conservation services, Nitzberg said. So, she decided to set up her own shop in Jenkintown in 1992. Her first client was a scholar who needed some newspaper clippings from the early 20th century cleaned and mounted for his studies.

Other work quickly came her way, she said. "For two years, I had no vacations," she continued. "I worked day and evening. Just word-of-mouth in the Philadelphia book world was what allowed me to stay in business and to succeed."