THE FUTURE of many a piece of antique textile may hang by a hair - human hair.

The use of hair as very fine thread for repairs of quilts, Chinese embroidery and other valuable stitchery is a subject of debate between two leading conservators in the textile field here.

These women do restoration for the Textile Museum and for the Museum of History and Technology of the Smithsonian Institution.

Clarissa Palmai, conservator at the Textile Museum at 2320 S St. NW, has used hair for years when very fine stitches are needed to hold together some priceless heirloom.

But Lois Vann, textile specialist at the Smithsonian's Museum of History and Technology at 14th St. and Constitution Ave. NW, has no use for hair.

"There is too much oil in hair," said Vann. "We prefer to use the warp threads of very fine silk."

Vann's classes for the Smithsonian Associates are already filled through September.

Palmai's series at the Textile Museum is free and is held the first Saturday in every month, from 10 a.m. to noon.

Usually around 50 people attend these sessions. One of the first questions is "How do I stop the deteriorations of my heirloom quilts, rugs, tapestries, old samplers, embroideries and any textile fragments?"

These have come out of old family trunks stored away in attics over the years and are in need of instant care before they fall apart.

"We are prepared to answer the most important question: How to do the repair?" said Palmai.

"Most people are surprised by one technique of repairing very fragile textiles by the use of human virgin hair."

Where does the hair come from? In her case, it comes from the head of her mother, Helene Kovacs, who was formerly conservator at the textile museum. Palmai succeeded her mother and has been at the museum for 13 years.

Her mother has long hair, partly dark and partly gray. After it is washed, Palmai combs it and collects the long strands for use in her work at the museum.

She said the gray strands are the stronger.

To repair with human hair, you must catch the broken material underneath with hair stitches and then take several holding hair stitches on top - a procedure known as "combing" in embroidery circles. Palmai advises the finest needle possible to use the hair.

She said the first step on preservation is proper cleaning. She does not advise tackling dry-cleaning yourself, but suggests engaging a professional cleaner who will know the type of cleaning solution needed for the exact material.

For those who want to be do-it-yourselfers in the use of water, she suggests a mild soap known as Orvus. The Textile Museum encourages people to try to do everything themselves. Yet she warns that many an amateur has ruined heirloom textiles for lack of knowledge of couching, cleaning, and framing. This is why the monthly class demonstrations are held.

Vann at the Smithsonian gives people a leaflet saying that antique cotton and linen quilts "should not be dry-cleaned," but should be given the "water treatment."

"Wet-cleaning differs from regular washing," says the leaflet, "in that the wet textile is not beaten or agitated in any way."

First the quilt is tested for the color fastness of the dyes used in its design, then it is laid flat and a low power hand vacuum cleaner in run over it to remove surface dust.

"Begin wet-cleaning by placing the quilt on a piece of Fiberglas-coated window screening," Vann's leaflet continued. "The submerge it in plain water heated to about 90 degrees F. Use soft or deionized water; do not use hard water as mineral salts in hard water may be deposited on the quilt."

She warns that if soaking does not remove the dirt, then a mild detergent could be used. Not one meant for the family wash, but one marked "mild." Rinsing is vital. As many as seven rinses may be needed, she said. She also warns against exposing any quilt to direct sunlight since sunlight may weaken fibers and fade fast colors. To dry, lay if flat on the floor over a piece of plastic sheeting.

The Smithsonian classes tell how to preserve everything from Grandma's quilts to a flag that Grandpa may have carried in the Civil War.

The classes have been divided into four main subjects with a final show-and-tell session in which students bring in their problem textiles.

Then they tour the Museum of History and Technology and see how Martha Washington's dress has been preserved in the First Ladies Hall and how George Washington's tent is still fit for a good night's sleep.

Don't mention the word "washing machine" to any of the experts at the Smithsonian on the subject of washing fine antique textiles.

When I asked an aide of Vann about the use of the washing machine, she shot back, "Heavenly days, no, but let me give you an expert."

She summoned Katherine Dirks, conservator in the textile division, who was equally emphatic. Does she ever use a washing machine to clean antique textiles?

"Absolutely no," said Dirks.

Palmai at the Textile Museum was just as positive.

"No, m'am, we never use a washing machine," she said. "It's all laundered by hand - the old-fashioned way."