THERE'S EVERY SIGN these days that we are entering into a period of change in interior design.

You have to put the evidence all together: critiques by Washington furniture buyers on what they saw recently at the furniture markets in High Point, N.C., where most Washington retailers shop; reports from Dallas, Los Angeles and Chicago furniture markets; conversations with interior designers; model homes by bigstore decorating firms; pritures in the high-style interior design magazines; manufactures' brochures; Rosalynn Carter's pottery in the White House State Dining Room, and that hard-to-explain reaction that begins with the eye and travels down the spine which means something significant is coming along.

For the last few years, interior design has been what best could be described as "safe." It's been a very permissive period, with wide variances accepted. Electic has been the watchword, and eclectic, as everybody knows really means "anything goes."

Perhaps it's because a great many people are convinced this Have Society won't last foever; or because the 21st century is no longer as far off as it once was; or because a great many people who might have bought cars, remodeled their house instead.

Whatever the reason, the results are beginning to be felt in interior design. None of this means you need go home and give everything in your house to the Goodwill Industries. (Though they would no doubt be glad to have it because they've had a hard time recently what with everybody either holding on to their goods or selling them in garage sales.) Nor does it mean that everybody's house is going to look exactly alike when the millennium comes.

What it does mean is we're probably entering a period when, if you're not sending children to college this year and you're feeling a bit more prosperous, you just might want to paint some walls, buy some new furniture or move it from one room to another.

Strong trends:

The rise of the one-of-a-kind theory of decorating. The end of the furniture suite. The revival of furniture as art object.

In the last few years, as a by-product of the crafts revival and to answer the demand for custom work, a number of craftsworkers have organized themselves into small financially viable mini-factories which, unlike the big mass manufacturers, are able to do small, limited-edition production to order.

In Washington, Mark Young of Kensington is gaining a great reputation for the Plexiglas tables he does for Theodore's Contemporary Furniture and some interior designers. His newest design for Theodore's, according to the firm's buyer, Karen Johnson, is an all-lucite-and-brass four-poster bed. Jeffrey Bigelow of Georgetown already has a national reputation for his jewel-like (diamond-priced) Plexiglas tables. Barry Woodard of Beltsville makes a dining table with brass strips on the base and sides as well as mirror tops and silver-strip sides for Woodward & J Sloane, Inc., furniture chain, Theodore's, Danker Showcase of Fine Furniture, Town House Furniture and Modern Living furniture.

Sculptor/woodworker Peter Danko of Alexandria has set up his wown shop with a group of other craftsworkers to show and sell his individually designed dining tables.

Steve Newman, owner of The Design Store, who has made money hand over fist with his design-it-yourself sofa, now epects to go into design-it-yourself case goods. He has a small manufacturing company which will produce chests, tables and storage pieces to the customer's order. The customer specifies the size, the leg, the hardware, the wood and the finish.

Mass manufacturers are trying to offer individuality to the customer by making modular seating pieces and storage units so they can be assembled in many ways to suit. Metro of Herndon, whose sofas are sold by Scan, turns out such a quality of work, the Danish quality control office bought one to check out, according to Frank Ellrich, the Falls Church Scan manager.

The end of the white wall. Prophesized for the last year or two, it now seems as though the end is in sight.

Jack Denst, the Chicago wall mural designer in town the other day, said "No more white walls. They're finished. I'm thinking about silvery blue. Not gray, but silver, pastel."

House & Garden, which annually wtudies color trends and reports on them first to the manufacturers, will tell consumers in its September issue that the "Wintergreens . . . cleaner, cooler, crisper" are new, with accents of coming-up colors Reef Blue and Persian Tuquoise.

The highest fashion walls seem to be very, very dark - brown, brown-black, and even a deep black. These dark walls today are different from the ones some of us remember from the early 1950s, when the deep "decorator" paints came on the market. The new darks are shiny, often slicked by coats of lacquer atop the paint.

Bloomingdale's recently did such a brown wall room in a model house in suburban Reston with Mascheroni furniture. In Architectural Digest magazine's latest issue, no less than three different designers in different parts of the country had painted their walls dark. In the recent Washington Assn. of Interior Designers' tour, two of three had either dark black or dark brown walls. In te model room Angelo Donghia did as a background for his furniture by Kroehler, he used black walls with the moulding painted white.

There are, however, still a great many who believe in the natural colors, soft backgrounds for casual living.

A new emphasis on the romantic, even the fantastic, in decorating.

The Cooper Hewitt Museum's recent New York show of objects from Britain's Brington Pavilion is part of the trend.

F.J. Mannarino, vice president of W J Sloane here, sees the exotic trend in the Korean chests, the Baker Furniture Co. Far East flavor.

GGeorge Kovacs, the New York lamp company, is importing bamboo rice paper fans, designed by Ingo Maurer of Germany, among the most beautiful lamps in the fantastic fashion. The lamps, most of them hanging, but one for wall and one for table, are composed of from one to 30 fans that form the shades.

They will be carried here by Georgetown Lamp Gallery.

Some of the nostalgia pieces are enough to make one long for the good new days. (There is even, it must be reported, a reproduction pull-chain toilet available on the market - $495.)

But here and there, one or two manufacturers, perhaps by accident, make nostalgia pieces that are acceptable. In that catagory are Hickory Furniture Co.'s "Promenade" using ball and spool turning on a cane back chair, a three-panel screen and a storage chest. Pulaski Furniture Corp. sold out of "Apothecary," its new nostalgia collection.

In the antique reproduction field, Baker Furniture's new Historic Charleston collection, according to Claus Mahnken, who is Woodward & Lothrop's home fashions coordinator, is the Rools-Royce of reproductions. Some experts expect the new Charleston reproductions to rival Kittinger's Williamsburg reproducations, until now the leader in the field. Kittinger, meanwhile, is now adding Federal Period pieces to its collection.

Both Mahnken and Mannarino see brass and bronze as looking newer than chrome for accents and bases for glass.

The arrival of modern as the most popular basic style. One buying association newsletter advocated stocking as much contemporary design as all the others put together.

Most of the modern sofas are still in modular units, the "passion pit" or "playpen" put-togethers.

Much talked about by design professionals are the designs of Pierre Cardin of Paris and Angelo Donghia, a New York designer, both of whom have their names on medium-priced furniture designs. Cardin designed for Laurel Lamp Manufacturing Co; Cardin will be carried locally by Woodward & Lothrop, says Mahnken. Donghia's concepts were manufactured by Kroehler, and will be carried locally by the Hecht Co., according to George Barber, their home furnishings director.

Both these two, and some remarkably dramatic pieces by Vladamir Kagen, a New York designer, are in essence Moderne - borrowing their sleek, mirrored surfaces from the 1920s as well as that era's overstuffed look. Kagen's chaises are in a high-price category but are equally high on people's wish list. His most surprising piece is the chaise whose invisible base makes it look as though it's floating. His work is carried by Bloomingdale's and Theodore's.

Also borrowed from the '20s are the great number of furniture pieces made of burled wood, among them a Schoolfield of Mullins, S.C., china cabinet and a Tomlinson of High Point burled Chinese-influenced dining suite.

Thayer Coggins Co. of High Point, having explored the influence of Mackintosh, the art nouveau deisgner in recent years, is now putting out a chair which derives from Le Corbusier, an art moderne pioneer.

Knoll, a pioneer in modern, is introducing new designs this fall by the late Mies van der Rohe and Lilly Reich, the Bauhaus pioneers: the MR reclining frame chair, the MR armless chaise longue and coffee table, the Brno chair with tubular frame and the Tugendhat chair with arms. Another variation is the Tugendhat chair (named for the house for which it was designed) and a modified MR chair covered in fabric as well.

Equally strong is the new wmphasis on storage and utility.

Mannarino notes that it is even possible now to have storage walls in traditional designs. Sarah Boyer Jenkins, also of Sloane's, points out that wall systems are now in some instances becoming the ealls. Woodward & Lothrop's Mahnken especially liked the Thomasville wall units and a two-piece armoire fitted for a bar.

The rumor is also out that at last the lounger chair, which most often lookled like a torture device from Star Trek, is being redesigned to more gainly proportions. Meanwhile, there has been a great success for the living room chaise, often assembled from modular units.

The insistence on real materials - wood, leather, ceramic and wool - still continues unabated and indeed seems stronger than ever. And the companion emphasis today seens to be, surprise, quality - even if you have to pay a bit more.

All of this is of course, as of the end of May 1977. Though the orders have been placed this spring, the furniture won't be in the stores until fall, when people come in from the garden and the swimming pool.

But now that you know what's news, you can save your pennies all summer to buy it, unless you decide to forget about the whole thng and spend your cushion dollars on a nice soft sandy beach.