TODAY, IF YOU have talent and persistence, you can paint your interiors the way George Washington did.

In Mount Vernon's scholarly current redecoration one of the loveliest paint finishes being used is the glaze, a translucent film of color brushed over flat paint on woodwork.

In two rooms at Mount Vernon, where the pigments and mediums used are exact copies of those used in 1799, the first layer of flat paint is a light shade of opaque Prussian blue (mixed with white). Over this is applied a glaze of linseed oil mixed with a small amount of pure Prussian blue pigment thinned with turpentine. In the 18th century a glaze was used partly to save money. The effect gives more depth of color using less paint. The result was marvelously luminous, lively and durable. The same technique could, of course, be used on walls.

A do-it-yourselfer, more concerned with effect than authenticity, might consider using stand oil instead of linseed oil, tins of pure color already ground in oil instead of dry powdered colors, and good quality mineral spirits instead of turpentine. A little japan drier can be added -- about 3 percent of the total volume. All these are available at local paint stores.

More difficult, but still possible for an amateur, is wood graining, an imitation of real woods such as rosewood or mahogany using umber or sienna glazes over flat paint. This process requires careful study of natural wood grains, lots of testing and practice, and comb-like brushes. (Rags, fingers, sponges, and cheese-cloth swabs can all be used.)

At Mount Vernon some fine examples can be seen in the center passage and in Washington's study at the south end of the house. The graining was done by Malcolm Robson, an English craftsman who has also grained wood at Woodlawn. In the passage the main color used is burnt sienna. The baseboards are lamp black. Graining, which transformed the plainness of the universally used pine, was much in vogue in the 18th century. Monticello, Thomas Jefferson's home, has recently grained its doors.

An indication of the local skills available to Washington is found in the Maryland Gazette for June 26, 1760. "House painter ran away from the subscriber. A convict servant named John Winters, a very compleat house painter. He can imitate marble or mahogany very exactly and can paint floor cloths as neat as any imported from Britain." The notice went on to say that the painter had worked for Colonel Washington near Alexandria.

Before restoration could begin at Mount Vernon, a thorough scientific analysis had to be made to find out exactly how the walls and woodwork (interior and exterior) had been treated in 1799, the target year. Matthew Mosca of New York City, with training in architectural history, chemistry and technical aspects of pigments, and called in about two years ago. Mosca had been studying and working on restorations of National Trust for Historic Preservation properties since 1973, among them Lyndhurst (Tarrytown, N.Y.), Oatlands (Leesburg, Va.), Drayton Hall (Charleston, S.C.), and Woodlawn Plantation.

Mosca first collected more than 2,000 cross-section samples of paint from woodwork and plaster throughout the house. He found samples of 18th-century paint in every room. To identify pigments, these were examined microscopically and analyzed chemically, especially the early layers.

For instance, it is known that laboratory sodium sulfide blackens samples of old lead-white pigment, but does not change zinc-oxide white. Since the latter was not available until 1850, any white pigments turning black in tests would have been used before that date.

According to Mosca, most rooms at Mount Vernon had three 18th-century finishes. He says he was lucky in starting with the south study, where one wall (a book press) was added in 1786, leaving the old paint still to be seen on the wall behind. The first finish on the press wall was the third finish on the other three walls.

In the 1780s, neoclassical plaster decorations by Robert Adams were added and many rooms were repainted in fashionable Prussian blue, "patent" yellow or Verdigris green. Mosca discovered the following passage in the 1797 Encyclopedia Britannica: "The only simple green color that hath a tolerable degree of brightness is Verdigris or preparations of it. This however, though a beautiful color, is far from being durable." Mosca will be very interested to see how the rooms age following completion of the restoration. They should age just as they would have in the 18th century.

Another clue found in the analysis was airborne dust particles between the finished paint layers. After Washington's death more dirt accumulated because the house was left unpainted until the 1820s. An uncolorful period of nearly all white or gray then began.

By 1799 these colors had been used: white lead, the basic material for mixing and also applied straight for some ceilings; a great deal of Prussian blue (discovered in 1704); Verdigris green; French yellow ocher; lamp black (obtained then, as now, by collecting soot from burning oils, fats, etc.) for baseboards; burnt umber for baseboards and doors; raw and burnt sienna and raw umber for tinting and graining; and "patent" yellow, a lead oxide, in the Nellie Custis bedroom.

The yellow has been simulated using titanium oxide yellow; "patent" yellow has proved to turn gray very quickly. Outside, the roofs were Spanish brown (red ocher). Tests are under way to decide whether a substitute will be used in the restoration of the roof. White paint has been mixed with sand on some of the exteriors as well as the main house to reproduce the original stone-like texture. In Washington's day the sand was thrown onto the wet paint; now a blower has been used.

Verdigris green, no longer available commercially, has been prepared especially for the restoration by a chemical house. In 1799 it was made by suspending copper plates over vats of vinegar. The fumes formed a green substance (cupric acetate) on the surface of the copper. This was scraped off, ground up and sold as "Common Verdigris." A more durable and brighter distillation was usually used at Mount Vernon.The "Common Verdigris" was ground, dissolved in sulfuric acid, and combined with white arsenic.

In 1784 Washington ordered three of the rooms wallpapered: the large dining room and two bedrooms. From wallpaper fragments from the dining room, the fiber mix was reproduced exactly by Brunschwig & Fils, New York City. But 18th-century wallpaper was not produced in a continuous roll as it is today, so the paper was cut into sheets of the correct widths (21 inches) and lengths (28 inches), rejoined and painted (called "staining" in the 18th century) using special brushes for the right textural effect.

In a dramatic restoration, Brian Powell, master plaster restorer, is saving an over-mantle decoration from 1775. An accumulation of paint layers had created tensions that were pulling off the skin of the plaster. Powell is removing the paint, a most delicate process, and injecting the plaster with consolidating acrylic. When the ornate plasterwork is once again stable, it can be painted the original Verdigris green.

In addition to chemical and microscopic analysis, much of Mosca's work has been made possible by documents from the period, including George Washington's original orders for large amounts of paint.