THERE IS A phrase, horror vacui (fear of emptiness), which explains very well the distaste some eras have for the plain, simple, unadorned surface. The phrase might have been invented to describe the show "Paint on Wood: Decorated American Furniture Since the 17th Century."

The exhibit opened last week at the Renwick Gallery of the Smithsonian's National Collection of Fine Arts, 17th Street and Pennsylvania Avenue NW, and continues through Nov. 6.

After years of "less is more," we are looking once again at ornament and trying it to see if it pleases our late 20th-century eyes, long unaccustomed to appreciating painted roses, gilded cupids and wood graining.

The Renwick show, organized by director Lloyd Herman and installed by Michael Monroe, is a collection of paintings of furniture from the colonial period through to the present. The colorful and elaborate pieces are set in Monroe's appropriately plain platforms of raw pine and white plaster, so they can be viewed easily and without distraction. The labels, for a change, are informative and go some way toward sorting things out for the interested viewer.

The selection is so good you will want to run from the Empire (1815-40) fainting couch to the 1976 stylized "Maple Mable Chest" by John Stanley, saying, "but look at this one."

A Hadley Hatfield area chest (1675-1710), one of the best-known distinctive types of painted furniture, introduces the exhibit. The chest is one of about 150 still existing. Most were made as dowry chests for young women contemplating matrimony. Nearby is the kas, a large cupboard from a Ducth household, painted with fruit, flowers and cherubs in gray(grisaille), as it is called.

A more sophisticated piece is the Boston high chest (circa 1740-60) of maple with white pine, japanned with oriental figures with charming and optimistic faces. Japanning is a simplified version of lacquering, using paint on wood with raised gesso (plaster of Paris) decorations, dusted with metalic powder and many coats of clear varnish. More amateur versions omitted the raised decorations and the metal powder.

Closer to home is the settee (circa 1800-10) from Baltimore, attributed to Hugh and John Finlay, two Irish brothers who made "fancy chairs." According to the catalog, the brothers advertised in 1805, "Cane seat chairs, sofas, recess and window seats of every description and all colors, gilt ornamented and varnished in a stile (sic) not equalled on the continent - with real Views, Fancy Landscapes, Flowers, Trophies of Music, War, Husbandry, Love &c.&c." On the back of the settee shown are three Baltimore buildings, the Baltimore Bank Building (now lost) and Mount Clair and Homewood, two fine houses thankfully still extant.

In a bit of chauvinism and revisionist history, the catalog points out that in Boston, Samuel Gragg "offered bentwood furniture designs that preceded by some years those of the Austrain Michael Thonet. Gragg's chair and settee designs relied on beechwood, bent by steam to form stiles, seat frames and legs in one continuous, curving piece."

The chair shown is remarkably handsome with its open, curved slates, embellished with the lightest of lines, including a peacock feather.

The fainting couch, in the Empire manner, was made of ash, white pine, tulip and cherry and points out one of the reasons painting on furniture was so popular. When the whole surface was covered, it didn't matter that the craftsman used various different woods as suited his needs and pocket-book since it eliminated the need to tediously match grains, with or without the help of veneers. The Empire period was greatly influenced by Napoleon's Egyptian adventures. Herman pointed out that in some cases stenciling imitated painted designs imitating ormolu (gilt bronze appliques). In the cheaper furniture, bronze powder often was used instead of the more expensive gold leaf.

One of the prime examples of stenciling is the Lamber Hitchcock chair, represented in the show by a circa 1825-32 version. The chair has remained popular when other decorated furniture has not. But its familiarity makes it one of the less interesting pieces in the show.

On the other hand, the late 18th-or 19th-century New Mexico chest, tempera on gesso on pine, is not only handsomely embelished, but has a pleasing shape, with sturdy legs making an even line with the sides. The hardware is worth an especially careful look.

There are chests, trunks, boxes and a Boston rocker, all representing the foliage and figures taught genteel young ladies at female seminaries.

Gail and Norbert Savage of Illinois have collected a great number of boxes in measured sizes illustrating the various techniques of graining including those done with stamps, sponge, corks, combs, feathers and rags.

The matched set of manufactured furniture came into popularity by the middle of the 19th cnetury. A decorated bedroom set might include; chest, bed, commode, dressing table, night stand, towel stand, wash stand and chair.

The painted "cottage sets" of the period were, according to Alexander Jackson Downing writing in 1820 (and quoted in the Renwick show), "highly finished, and usually painted drab, white, a delicate lilac, or a fine blue - the surface polished and hard, like enamel. Some of the better sets have groups of flowers or other designs painted upon them with artistic skill. When it is remembered that the whole set for a cottage bedroom may be had for the price of a single wardrobe in mahogany, it will be seen how comparativley cheap it is."

Around the corner from a cottage chest, and a good way to judge the difference between kitsch and class, is a fine writing desk designed by Arthur F. and Lucia K. Mathews of San Francisco in 1915. The carved, incised and painted mahogany uses California flowers and fruits set against pioneers of the Arts and Crafts Movement in the United States, one of the more rustic representations of the Art Nouveau movement. The Arts and Crafts furniture, often in oak, includes the Mission Style, an early 1900s revival of the style of furniture supposed to have been used by Spanish missionaries in California. Mission furniture currently is enjoying a revival after languishing for years in the junk shops.

Likely to be one of the most popular chairs in the show is the very handsome (1930) art moderne chair, attributed to architect Hal Pereira, a set designer who won an Oscar for "The Rose Tattoo." Pereira says he can't remember designing the chair and anyway he never liked art moderne. But the chair's original owner credits him with it. He shouldn't be ashamed. The ebonized wood with pewter inlay is part of a dining room ensemble designed for a Chicago apartment. Credit goes to Lloyd Herman for digging the chair out of the basement of the Chicago Historical Society, but he gets demerits for not bringing the whole suite.

The Peter Hunt 1947 blanket chest is in the quaint and cutesy mode, reviving the least interesting periods of painted decoration.

But in the section of work of contemporary artist-craftspeople are several handsome, original and nonderivative late pieces. It gives us hope that perhaps we are entering into another period of good design. Isabel O'Neill, who taught fake marbling to many through the home magazines, is represented by a "fantasy tiger eye." Alan Siegel's chair on a splendid three-legged shape is enameled with a face on the back. Jeremy Samson's waterfall table is stained plywood, intricately worked. Kate Milner-Wright's music cabinet is a fantasy piece with three-dimensional clouds. Tommy Simpson's offering is another one of his grandpop clocks. And John Stanley's handsome chest has a stylized pattern of rocks, roots, trees and skies. The Stanley chest is well displayed in an alcove that seems its natural home.

The Renwick show, coming at a time when we can once again look at objects from England's Brighton pavilion that are now on exhibit in New York without bursting into laughter, is bound to have an influence on the way we look at things. Perhaps, gritting our teetch, a number of us will lay down that can of paint stripper and learn to love roses.